lua-resty-template is a compiling (1) (HTML) templating engine for Lua and OpenResty.
(1) with compilation we mean that templates are translated to Lua functions that you may call or string.dump
as a binary bytecode blobs to disk that can be later utilized with lua-resty-template
or basic load
and
loadfile
standard Lua functions (see also Template Precompilation). Although,
generally you don't need to do that as lua-resty-template
handles this behind the scenes.
local template = require "resty.template" -- OR
local template = require "resty.template.safe" -- return nil, err on errors
-- Using template.new
local view = template.new "view.html"
view.message = "Hello, World!"
view:render()
-- Using template.render
template.render("view.html", { message = "Hello, World!" })
<!DOCTYPE html>
<html>
<body>
<h1>{{message}}</h1>
</body>
</html>
<!DOCTYPE html>
<html>
<body>
<h1>Hello, World!</h1>
</body>
</html>
The same can be done with inline template string:
-- Using template string
template.render([[
<!DOCTYPE html>
<html>
<body>
<h1>{{message}}</h1>
</body>
</html>]], { message = "Hello, World!" })
- Template Syntax
- Installation
- Nginx / OpenResty Configuration
- Lua API
- template.root
- template.location
- table template.new(view, layout)
- boolean template.caching(boolean or nil)
- function, boolean template.compile(view, cache_key, plain)
- function, boolean template.compile_string(view, cache_key)
- function, boolean template.compile_file(view, cache_key)
- template.visit(func)
- string template.process(view, context, cache_key, plain)
- string template.process_string(view, context, cache_key)
- string template.process_file(view, context, cache_key)
- template.render(view, context, cache_key, plain)
- template.render_string(view, context, cache_key)
- template.render_file(view, context, cache_key)
- string template.parse(view, plain)
- string template.parse_string(view, plain)
- string template.parse_file(view, plain)
- string template.precompile(view, path, strip)
- string template.precompile_string(view, path, strip)
- string template.precompile_file(view, path, strip)
- string template.load(view, plain)
- string template.load_string(view)
- string template.load_file(view)
- template.print
- Template Precompilation
- Template Helpers
- Usage Examples
- FAQ
- Alternatives
- Benchmarks
- Changes
- Roadmap
- See Also
- License
You may use the following tags in templates:
{{expression}}
, writes result of expression - html escaped{*expression*}
, writes result of expression{% lua code %}
, executes Lua code{(template)}
, includestemplate
file, you may also supply context for include file{(file.html, { message = "Hello, World" } )}
(NOTE: you cannot use comma (,
) infile.html
, in that case use{["file,with,comma"]}
instead){[expression]}
, includesexpression
file (the result of expression), you may also supply context for include file{["file.html", { message = "Hello, World" } ]}
{-block-}...{-block-}
, wraps inside of a{-block-}
to a value stored in ablocks
table with a keyblock
(in this case), see using blocks. Don't use predefined block namesverbatim
andraw
.{-verbatim-}...{-verbatim-}
and{-raw-}...{-raw-}
are predefined blocks whose inside is not processed by thelua-resty-template
but the content is outputted as is.{# comments #}
everything between{#
and#}
is considered to be commented out (i.e. not outputted or executed)
From templates you may access everything in context
table, and everything in template
table.
In templates you can also access context
and template
by prefixing keys.
<h1>{{message}}</h1> == <h1>{{context.message}}</h1>
If you don't want a particular template tag to be processed you may escape the starting tag with backslash \
:
<h1>\{{message}}</h1>
This will output (instead of evaluating the message):
<h1>{{message}}</h1>
If you want to add backslash char just before template tag, you need to escape that as well:
<h1>\\{{message}}</h1>
This will output:
<h1>\[message-variables-content-here]</h1>
Say you have this kind of a context table:
local ctx = {["foo:bar"] = "foobar"}
And you want to render the ctx["foo:bar"]
's value foobar
in your template. You have to specify it explicitly
by referencing the context
in your template:
{# {*["foo:bar"]*} won't work, you need to use: #}
{*context["foo:bar"]*}
Or altogether:
template.render([[
{*context["foo:bar"]*}
]], {["foo:bar"] = "foobar"})
Only strings are escaped, functions are called without arguments (recursively) and results are returned as is,
other types are tostring
ified. nil
s and ngx.null
s are converted to empty strings ""
.
Escaped HTML characters:
&
becomes&
<
becomes<
>
becomes>
"
becomes"
'
becomes'
/
becomes/
local template = require "resty.template"
template.render("view.html", {
title = "Testing lua-resty-template",
message = "Hello, World!",
names = { "James", "Jack", "Anne" },
jquery = '<script src="js/jquery.min.js"></script>'
})
{(header.html)}
<h1>{{message}}</h1>
<ul>
{% for _, name in ipairs(names) do %}
<li>{{name}}</li>
{% end %}
</ul>
{(footer.html)}
<!DOCTYPE html>
<html>
<head>
<title>{{title}}</title>
{*jquery*}
</head>
<body>
</body>
</html>
It is advised that you do not use these keys in your context tables:
___
, holds the compiled template, if set you need to use{{context.___}}
context
, holds the current context, if set you need to use{{context.context}}
echo
, holds the echo helper function, if set you need to use{{context.echo}}
include
, holds the include helper function, if set you need to use{{context.include}}
layout
, holds the layout by which the view will be decorated, if set you need to use{{context.layout}}
blocks
, holds the blocks, if set you need to use{{context.blocks}}
(see: using blocks)template
, holds the template table, if set you need to use{{context.template}}
In addition to that with template.new
you should not overwrite:
render
, the function that renders a view, obviously ;-)
You should also not {(view.html)}
recursively:
template.render "view.html"
{(view.html)}
You can load templates from "sub-directories" as well with {(syntax)}
:
{(users/list.html)}
Also note that you can provide template either as a file path or as a string. If the file exists,
it will be used, otherwise the string is used. See also template.load
.
Just place template.lua
and
template
directory somewhere in
your package.path
, under resty
directory. If you are using OpenResty, the default location would
be /usr/local/openresty/lualib/resty
.
$ opm get bungle/lua-resty-template
$ luarocks install lua-resty-template
LuaRocks repository for lua-resty-template
is located at https://luarocks.org/modules/bungle/lua-resty-template.
When lua-resty-template
is used in context of Nginx / OpenResty there are a few configuration directives
that you need to be aware:
template_root
(set $template_root /var/www/site/templates
)template_location
(set $template_location /templates
)
If none of these are set in Nginx configuration, ngx.var.document_root
(aka root-directive) value is used.
If template_location
is set, it will be used first, and if the location returns anything but 200
as
a status code, we do fallback to either template_root
(if defined) or document_root
.
With lua-resty-template
2.0
it is possible to override $template_root
and $template_location
with
Lua
code:
local template = require "resty.template".new({
root = "/templates",
location = "/templates"
})
This one tries to load file content with Lua code from html
directory (relative to Nginx prefix).
http {
server {
location / {
root html;
content_by_lua '
local template = require "resty.template"
template.render("view.html", { message = "Hello, World!" })
';
}
}
}
This one tries to load file content with Lua code from /usr/local/openresty/nginx/html/templates
directory.
http {
server {
set $template_root /usr/local/openresty/nginx/html/templates;
location / {
root html;
content_by_lua '
local template = require "resty.template"
template.render("view.html", { message = "Hello, World!" })
';
}
}
}
This one tries to load content with ngx.location.capture
from /templates
location (in this case this is
served with ngx_static
module).
http {
server {
set $template_location /templates;
location / {
root html;
content_by_lua '
local template = require "resty.template"
template.render("view.html", { message = "Hello, World!" })
';
}
location /templates {
internal;
alias html/templates/;
}
}
}
See also template.load
.
You can setup template root by setting this variable which will be looked for template files:
local template = require "resty.template".new({
root = "/templates"
})
template.render_file("test.html")
This property overrides the one set in Nginx configuration (set $template_root /my-templates;
)
This is what you can use with OpenResty as that will use ngx.location.capture
to fetch templates
files in non-blocking fashion.
local template = require "resty.template".new({
location = "/templates"
})
template.render_file("test.html")
This property overrides the one set in Nginx configuration (set $template_location /my-templates;
)
Creates a new template instance that is used as a (default) context when render
ed. A table that gets created has
only one method render
, but the table also has metatable with __tostring
defined. See the example below. Both
view
and layout
arguments can either be strings or file paths, but layout can also be a table created previously
with template.new
.
With 2.0 the new can also be used without arguments, which creates a new template instance:
local template = require "resty.template".new()
You can also pass a table that is then modified to be a template:
local config = {
root = "/templates"
}
local template = require "resty.template".new(config)
This is handy as the template
created by new
does not share the cache with the global template returned
by require "resty.template"
(this was reported with issue #25).
You can also pass a boolean true
or false
as a view
parameter which means that either safe
or un-safe
version of template is returned:
local unsafe = require "resty.template"
local safe = unsafe.new(true)
There is also a default safe
implementation available:
local safe = require "resty.template.safe"
-- you can create instance of safe too:
local safe_instance = safe.new()
safe
version uses return nil, err
Lua error handling pattern and unsafe
just throws the errors, which you
can catch with pcall
, xpcall
or coroutine.wrap
.
Here are examples of using new
with arguments:
local view = template.new"template.html" -- or
local view = template.new("view.html", "layout.html") -- or
local view = template.new[[<h1>{{message}}</h1>]] -- or
local view = template.new([[<h1>{{message}}</h1>]], [[
<html>
<body>
{*view*}
</body>
</html>
]])
local template = require "resty.template"
local view = template.new"view.html"
view.message = "Hello, World!"
view:render()
-- You may also replace context on render
view:render{ title = "Testing lua-resty-template" }
-- If you want to include view context in replacement context
view:render(setmetatable({ title = "Testing lua-resty-template" }, { __index = view }))
-- To get rendered template as a string, you can use tostring
local result = tostring(view)
This function enables or disables template caching, or if no parameters are passed, returns current state of template caching. By default template caching is enabled, but you may want to disable it on development or low-memory situations.
local template = require "resty.template"
-- Get current state of template caching
local enabled = template.caching()
-- Disable template caching
template.caching(false)
-- Enable template caching
template.caching(true)
Please note that if the template was already cached when compiling a template, the cached version will be returned.
You may want to flush cache with template.cache = {}
to ensure that your template really gets recompiled.
Parses, compiles and caches (if caching is enabled) a template and returns the compiled template as a function
that takes context as a parameter and returns rendered template as a string. Optionally you may pass cache_key
that
is used as a cache key. If cache key is not provided view
wil be used as a cache key. If cache key is no-cache
the template cache will not be checked and the resulting function will not be cached. You may also optionally
pass plain
with a value of true
if the view
is plain text string (this will skip template.load
and binary
chunk detection in template.parse
phase). If plain
is false
the template is considered to be a file,
and all the issues with file reading are considered as errors. If the plain
is set to nil
(the default)
the template does not consider file reading errors as fatal, and returns back the view
(usually the path of
the template).
local func = template.compile("template.html") -- or
local func = template.compile([[<h1>{{message}}</h1>]])
local template = require "resty.template"
local func = template.compile("view.html")
local world = func{ message = "Hello, World!" }
local universe = func{ message = "Hello, Universe!" }
print(world, universe)
Also note the second return value which is a boolean. You may discard it, or use it to determine if the returned function was cached.
This just calls template.compile(view, cache_key, true)
This just calls template.compile(view, cache_key, false)
Allows you to register template parser visitor functions. Visitors are called in the order they are registered. And once registered, cannot be removed from parser. Perhaps it is easier to show how it works:
local template = require "resty.template.safe".new()
local i = 0
template.visit(function(content, type, name)
local trimmed = content:gsub("^%s+", ""):gsub("%s+$", "")
if trimmed == "" then return content end
i = i + 1
print(" visit: ", i)
if type then print(" type: ", type) end
if name then print(" name: ", name) end
print("content: ", trimmed)
print()
return content
end)
local func = template.compile([[
How are you, {{user.name}}?
Here is a new cooking recipe for you!
{% for i, ingredient in ipairs(ingredients) do %}
{*i*}. {{ingredient}}
{% end %}
{-ad-}`lua-resty-template` the templating engine for OpenResty!{-ad-}
]])
local content = func{
user = {
name = "bungle"
},
ingredients = {
"potatoes",
"sausages"
}
}
print(content)
This will output the following:
visit: 1
content: How are you,
visit: 2
type: {
content: user.name
visit: 3
content: ?
Here is a new cooking recipe for you!
visit: 4
type: %
content: for i, ingredient in ipairs(ingredients) do
visit: 5
type: *
content: i
visit: 6
content: .
visit: 7
type: {
content: ingredient
visit: 8
type: %
content: end
visit: 9
type: -
name: ad
content: `lua-resty-template` the templating engine for OpenResty!
visit: 10
content: `lua-resty-template` the templating engine for OpenResty!
How are you, bungle?
Here is a new cooking recipe for you!
1. potatoes
2. sausages
The visitor functions should have this signature:
string function(content, type, name)
If the function doesn't modify the content
it should return the content
back, like the visitor
above does.
Here is a bit more advanced visitor example that handles run-time errors on expressions:
local template = require "resty.template".new()
template.render "Calculation: {{i*10}}"
This will runtime error with:
ERROR: [string "context=... or {}..."]:7: attempt to perform arithmetic on global 'i' (a nil value)
stack traceback:
resty/template.lua:652: in function 'render'
a.lua:52: in function 'file_gen'
init_worker_by_lua:45: in function <init_worker_by_lua:43>
[C]: in function 'xpcall'
init_worker_by_lua:52: in function <init_worker_by_lua:50>
Now let's add a visitor that handles this error:
local template = require "resty.template".new()
template.visit(function(content, type)
if type == "*" or type == "{" then
return "select(3, pcall(function() return nil, " .. content .. " end)) or ''"
end
return content
end)
template.render "Calculation: {{i*10}}\n"
template.render("Calculation: {{i*10}}\n", { i = 1 })
This will output:
Calculation:
Calculation: 10
Parses, compiles, caches (if caching is enabled) and returns output as string. You may optionally also
pass cache_key
that is used as a cache key. If plain
evaluates to true
, the view
is considered
to be plain string template (template.load
and binary chunk detection is skipped on template.parse
).
If plain
is false"
the template is considered to be a file, and all the issues with file reading are
considered as errors. If the plain
is set to nil
(the default) the template does not consider file
reading errors as fatal, and returns back the view
.
local output = template.process("template.html", { message = "Hello, World!" }) -- or
local output = template.process([[<h1>{{message}}</h1>]], { message = "Hello, World!" })
This just calls template.process(view, context, cache_key, true)
This just calls template.process(view, context, cache_key, false)
Parses, compiles, caches (if caching is enabled) and outputs template either with ngx.print
if available,
or print
. You may optionally also pass cache_key
that is used as a cache key. If plain
evaluates to
true
, the view
is considered to be plain string template (template.load
and binary chunk detection
is skipped on template.parse
). If plain
is false"
the template is considered to be a file, and
all the issues with file reading are considered as errors. If the plain
is set to nil
(the default)
the template does not consider file reading errors as fatal, and returns back the view
.
template.render("template.html", { message = "Hello, World!" }) -- or
template.render([[<h1>{{message}}</h1>]], { message = "Hello, World!" })
This just calls template.render(view, context, cache_key, true)
This just calls template.render(view, context, cache_key, false)
Parses template file or string, and generates a parsed template string. This may come useful when debugging
templates. You should note that if you are trying to parse a binary chunk (e.g. one returned with
template.compile
), template.parse
will return that binary chunk as is. If plain
evaluates to
true
, the view
is considered to be plain string template (template.load
and binary chunk detection
is skipped on template.parse
). If plain
is false"
the template is considered to be a file, and
all the issues with file reading are considered as errors. If the plain
is set to nil
(the default)
the template does not consider file reading errors as fatal, and returns back the view
.
local t1 = template.parse("template.html")
local t2 = template.parse([[<h1>{{message}}</h1>]])
This just calls template.parse(view, plain, true)
This just calls template.parse(view, plain, false)
Precompiles template as a binary chunk. This binary chunk can be written out as a file (and you may use it
directly with Lua's load
and loadfile
). For convenience you may optionally specify path
argument to
output binary chunk to file. You may also supply strip
parameter with value of false
to make precompiled
templates to have debug information as well (defaults to true
). The last parameter plain
means that
should complilation treat the view
as string
(plain = true
) or as file path
(plain = false
) or
try first as a file, and fallback to string
(plain = nil
). In case the plain=false
(a file) and there
is error with file io
the function will also error with an assertion failure.
local view = [[
<h1>{{title}}</h1>
<ul>
{% for _, v in ipairs(context) do %}
<li>{{v}}</li>
{% end %}
</ul>]]
local compiled = template.precompile(view)
local file = io.open("precompiled-bin.html", "wb")
file:write(compiled)
file:close()
-- Alternatively you could just write (which does the same thing as above)
template.precompile(view, "precompiled-bin.html")
template.render("precompiled-bin.html", {
title = "Names",
"Emma", "James", "Nicholas", "Mary"
})
This just calls template.precompile(view, path, strip, true)
.
This just calls template.precompile(view, path, strip, false)
.
This field is used to load templates. template.parse
calls this function before it starts parsing the template
(assuming that optional plain
argument in template.parse
evaluates to false
or nil
(the default).
By default there are two loaders in lua-resty-template
: one for Lua and the other for Nginx / OpenResty.
Users can overwrite this field with their own function. For example you may want to write a template loader
function that loads templates from a database.
The default template.load
for Lua (attached as template.load when used directly with Lua):
function(view, plain)
if plain == true then return view end
local path, root = view, template.root
if root and root ~= EMPTY then
if byte(root, -1) == SOL then root = sub(root, 1, -2) end
if byte(view, 1) == SOL then path = sub(view, 2) end
path = root .. "/" .. path
end
return plain == false and assert(read_file(path)) or read_file(path) or view
end
The default template.load
for Nginx / OpenResty (attached as template.load when used in context
of Nginx / OpenResty):
function(view, plain)
if plain == true then return view end
local vars = VAR_PHASES[phase()]
local path = view
local root = template.location
if (not root or root == EMPTY) and vars then
root = var.template_location
end
if root and root ~= EMPTY then
if byte(root, -1) == SOL then root = sub(root, 1, -2) end
if byte(path, 1) == SOL then path = sub(path, 2) end
path = root .. "/" .. path
local res = capture(path)
if res.status == 200 then return res.body end
end
path = view
root = template.root
if (not root or root == EMPTY) and vars then
root = var.template_root
if not root or root == EMPTY then root = var.document_root or prefix end
end
if root and root ~= EMPTY then
if byte(root, -1) == SOL then root = sub(root, 1, -2) end
if byte(path, 1) == SOL then path = sub(path, 2) end
path = root .. "/" .. path
end
return plain == false and assert(read_file(path)) or read_file(path) or view
end
As you can see, lua-resty-template
always tries (by default) to load a template from a file
(or with ngx.location.capture
) even if you provided template as a string. lua-resty-template
.
But if you know that your templates are always strings, and not file paths, you may use plain
argument in template.compile
, template.render
, and template.parse
OR replace template.load
with the simplest possible template loader there is (but be aware that if your templates use
{(file.html)}
includes, those are considered as strings too, in this case file.html
will
be the template string that is parsed) - you could also setup a loader that finds templates in
some database system, e.g. Redis:
local template = require "resty.template"
template.load = function(view, plain) return view end
If the plain
parameter is false
(nil
is not treated as false
), all the issues with file
io are considered assertion errors.
This just calls template.load(view, true)
This just calls template.load(view, false)
This field contains a function that is used on template.render()
or
template.new("example.html"):render()
to output the results. By default this holds either
ngx.print
(if available) or print
. You may want to (and are allowed to) overwrite this
field, if you want to use your own output function instead. This is also useful if you are
using some other framework, e.g. Turbo.lua (http://turbolua.org/).
local template = require "resty.template"
template.print = function(s)
print(s)
print("<!-- Output by My Function -->")
end
lua-resty-template
supports template precompilation. This can be useful when you want to
skip template parsing (and Lua interpretation) in production or if you do not want your
templates distributed as plain text files on production servers. Also by precompiling,
you can ensure that your templates do not contain something, that cannot be compiled
(they are syntactically valid Lua). Although templates are cached (even without precompilation),
there are some performance (and memory) gains. You could integrate template precompilation in
your build (or deployment) scripts (maybe as Gulp, Grunt or Ant tasks).
local template = require "resty.template"
local compiled = template.precompile("example.html", "example-bin.html")
local template = require "resty.template"
template.render("example-bin.html", { "Jack", "Mary" })
Echoes output. This is useful with {% .. %}
:
require "resty.template".render[[
begin
{%
for i=1, 10 do
echo("\tline: ", i, "\n")
end
%}
end
]]
This will output:
begin
line: 1
line: 2
line: 3
line: 4
line: 5
line: 6
line: 7
line: 8
line: 9
line: 10
end
This can also be written as but echo
might come handy in some cases:
require "resty.template".render[[
begin
{% for i=1, 10 do %}
line: {* i *}
{% end %}
end
]]
This is mainly used with internally with {(view.hmtl)}
, {["view.hmtl"]}
and
with blocks {-block-name-}..{-block-name-}
. If context
is not given the context
used to compile parent view is used. This function will compile the view
and call
the resulting function with context
(or the context
of parent view if not given).
While lua-resty-template
does not have much infrastucture or ways to extend it,
you still have a few possibilities that you may try.
- Adding methods to global
string
, andtable
types (not encouraged, though) - Wrap your values with something before adding them in context (e.g. proxy-table)
- Create global functions
- Add local functions either to
template
table orcontext
table - Use metamethods in your tables
While modifying global types seems convenient, it can have nasty side effects. That's why I suggest you to look at these libraries, and articles first:
- Method Chaining Wrapper (http://lua-users.org/wiki/MethodChainingWrapper)
- Moses (https://github.com/Yonaba/Moses)
- underscore-lua (https://github.com/jtarchie/underscore-lua)
You could for example add Moses' or Underscore's _
to template table or context table.
local _ = require "moses"
local template = require "resty.template"
template._ = _
Then you can use _
inside your templates. I created one example template helper
that can be found from here:
https://github.com/bungle/lua-resty-template/blob/master/lib/resty/template/html.lua
local template = require "resty.template"
local html = require "resty.template.html"
template.render([[
<ul>
{% for _, person in ipairs(context) do %}
{*html.li(person.name)*}
{% end %}
</ul>
<table>
{% for _, person in ipairs(context) do %}
<tr data-sort="{{(person.name or ""):lower()}}">
{*html.td{ id = person.id }(person.name)*}
</tr>
{% end %}
</table>]], {
{ id = 1, name = "Emma"},
{ id = 2, name = "James" },
{ id = 3, name = "Nicholas" },
{ id = 4 }
})
<ul>
<li>Emma</li>
<li>James</li>
<li>Nicholas</li>
<li />
</ul>
<table>
<tr data-sort="emma">
<td id="1">Emma</td>
</tr>
<tr data-sort="james">
<td id="2">James</td>
</tr>
<tr data-sort="nicholas">
<td id="3">Nicholas</td>
</tr>
<tr data-sort="">
<td id="4" />
</tr>
</table>
You may include templates inside templates with {(template)}
and {(template, context)}
syntax.
The first one uses the current context as a context for included template, and the second one replaces
it with a new context. Here is example of using includes and passing a different context to include file:
local template = require "resty.template"
template.render("include.html", { users = {
{ name = "Jane", age = 29 },
{ name = "John", age = 25 }
}})
<html>
<body>
<ul>
{% for _, user in ipairs(users) do %}
{(user.html, user)}
{% end %}
</ul>
</body>
</html>
<li>User {{name}} is of age {{age}}</li>
<html>
<body>
<ul>
<li>User Jane is of age 29</li>
<li>User John is of age 25</li>
</ul>
</body>
</html>
Layouts (or Master Pages) can be used to wrap a view inside another view (aka layout).
local template = require "resty.template"
local layout = template.new "layout.html"
layout.title = "Testing lua-resty-template"
layout.view = template.compile "view.html" { message = "Hello, World!" }
layout:render()
-- Or like this
template.render("layout.html", {
title = "Testing lua-resty-template",
view = template.compile "view.html" { message = "Hello, World!" }
})
-- Or maybe you like this style more
-- (but please remember that context.view is overwritten on rendering the layout.html)
local view = template.new("view.html", "layout.html")
view.title = "Testing lua-resty-template"
view.message = "Hello, World!"
view:render()
-- Well, maybe like this then?
local layout = template.new "layout.html"
layout.title = "Testing lua-resty-template"
local view = template.new("view.html", layout)
view.message = "Hello, World!"
view:render()
<h1>{{message}}</h1>
<!DOCTYPE html>
<html>
<head>
<title>{{title}}</title>
</head>
<body>
{*view*}
</body>
</html>
local view = template.new("view.html", "layout.html")
view.title = "Testing lua-resty-template"
view.message = "Hello, World!"
view:render()
{% layout="section.html" %}
<h1>{{message}}</h1>
<div id="section">
{*view*}
</div>
<!DOCTYPE html>
<html>
<head>
<title>{{title}}</title>
</head>
<body>
{*view*}
</body>
</html>
<!DOCTYPE html>
<html>
<head>
<title>Testing lua-resty-template</title>
</head>
<body>
<div id="section">
<h1>Hello, World!</h1>
</div>
</body>
</html>
Blocks can be used to move different parts of the views to specific places in layouts. Layouts have placeholders for blocks.
local view = template.new("view.html", "layout.html")
view.title = "Testing lua-resty-template blocks"
view.message = "Hello, World!"
view.keywords = { "test", "lua", "template", "blocks" }
view:render()
<h1>{{message}}</h1>
{-aside-}
<ul>
{% for _, keyword in ipairs(keywords) do %}
<li>{{keyword}}</li>
{% end %}
</ul>
{-aside-}
<!DOCTYPE html>
<html>
<head>
<title>{*title*}</title>
</head>
<body>
<article>
{*view*}
</article>
{% if blocks.aside then %}
<aside>
{*blocks.aside*}
</aside>
{% end %}
</body>
</html>
<!DOCTYPE html>
<html>
<head>
<title>Testing lua-resty-template blocks</title>
</head>
<body>
<article>
<h1>Hello, World!</h1>
</article>
<aside>
<ul>
<li>test</li>
<li>lua</li>
<li>template</li>
<li>blocks</li>
</ul>
</aside>
</body>
</html>
Say you have base.html
, layout1.html
, layout2.html
and page.html
. You want an inheritance like this:
base.html ➡ layout1.html ➡ page.html
or base.html ➡ layout2.html ➡ page.html
(actually this nesting is
not limited to three levels).
local res = require"resty.template".compile("page.html"){}
<html lang='zh'>
<head>
<link href="css/bootstrap.min.css" rel="stylesheet">
{* blocks.page_css *}
</head>
<body>
{* blocks.main *}
<script src="js/jquery.js"></script>
<script src="js/bootstrap.min.js"></script>
{* blocks.page_js *}
</body>
</html>
{% layout = "base.html" %}
{-main-}
<div class="sidebar-1">
{* blocks.sidebar *}
</div>
<div class="content-1">
{* blocks.content *}
</div>
{-main-}
{% layout = "base.html" %}
{-main-}
<div class="sidebar-2">
{* blocks.sidebar *}
</div>
<div class="content-2">
{* blocks.content *}
</div>
<div>I am different from layout1 </div>
{-main-}
{% layout = "layout1.html" %}
{-sidebar-}
this is sidebar
{-sidebar-}
{-content-}
this is content
{-content-}
{-page_css-}
<link href="css/page.css" rel="stylesheet">
{-page_css-}
{-page_js-}
<script src="js/page.js"></script>
{-page_js-}
Or:
{% layout = "layout2.html" %}
{-sidebar-}
this is sidebar
{-sidebar-}
{-content-}
this is content
{-content-}
{-page_css-}
<link href="css/page.css" rel="stylesheet">
{-page_css-}
{-page_js-}
<script src="js/page.js"></script>
{-page_js-}
@DDarko mentioned in an issue #5
that he has a use case where he needs to have macros or parameterized views. That is a nice feature that you can
use with lua-resty-template
.
To use macros, let's first define some Lua code:
template.render("macro.html", {
item = "original",
items = { a = "original-a", b = "original-b" }
})
And the macro-example.html
:
{% local string_macro = [[
<div>{{item}}</div>
]] %}
{* template.compile(string_macro)(context) *}
{* template.compile(string_macro){ item = "string-macro-context" } *}
This will output:
<div>original</div>
<div>string-macro-context</div>
Now let's add function macro, in macro-example.html
(you can omit local
if you want):
{% local function_macro = function(var, el)
el = el or "div"
return "<" .. el .. ">{{" .. var .. "}}</" .. el .. ">\n"
end %}
{* template.compile(function_macro("item"))(context) *}
{* template.compile(function_macro("a", "span"))(items) *}
This will output:
<div>original</div>
<span>original-a</span>
But this is even more flexible, let's try another function macro:
{% local function function_macro2(var)
return template.compile("<div>{{" .. var .. "}}</div>\n")
end %}
{* function_macro2 "item" (context) *}
{* function_macro2 "b" (items) *}
This will output:
<div>original</div>
<div>original-b</div>
And here is another one:
{% function function_macro3(var, ctx)
return template.compile("<div>{{" .. var .. "}}</div>\n")(ctx or context)
end %}
{* function_macro3("item") *}
{* function_macro3("a", items) *}
{* function_macro3("b", items) *}
{* function_macro3("b", { b = "b-from-new-context" }) *}
This will output:
<div>original</div>
<div>original-a</div>
<div>original-b</div>
<div>b-from-new-context</div>
Macros are really flexible. You may have form-renderers and other helper-macros to have a reusable and
parameterized template output. One thing you should know is that inside code blocks (between {%
and %}
)
you cannot have %}
, but you can work around this using string concatenation "%" .. "}"
.
You can call string methods (or other table functions) in templates too.
local template = require "resty.template"
template.render([[
<h1>{{header:upper()}}</h1>
]], { header = "hello, world!" })
<h1>HELLO, WORLD!</h1>
Sometimes you need to mix and match other templates (say client side Javascript templates like Angular) with server side lua-resty-templates. Say you have this kind of Angular template:
<html ng-app>
<body ng-controller="MyController">
<input ng-model="foo" value="bar">
<button ng-click="changeFoo()">{{buttonText}}</button>
<script src="angular.js">
</body>
</html>
Now you can see that there is {{buttonText}}
that is really for Angular templating, and not for lua-resty-template.
You can fix this by wrapping either the whole code with {-verbatim-}
or {-raw-}
or only the parts that you want:
{-raw-}
<html ng-app>
<body ng-controller="MyController">
<input ng-model="foo" value="bar">
<button ng-click="changeFoo()">{{buttonText}}</button>
<script src="angular.js">
</body>
</html>
{-raw-}
or (see the {(head.html)}
is processed by lua-resty-template):
<html ng-app>
{(head.html)}
<body ng-controller="MyController">
<input ng-model="foo" value="bar">
<button ng-click="changeFoo()">{-raw-}{{buttonText}}{-raw-}</button>
<script src="angular.js">
</body>
</html>
You may also use short escaping syntax:
...
<button ng-click="changeFoo()">\{{buttonText}}</button>
...
If you want to embed Markdown (and SmartyPants) syntax inside your templates you can do it by using for example
lua-resty-hoedown
(it depends on LuaJIT). Here is an example of
using that:
local template = require "resty.template"
template.markdown = require "resty.hoedown"
template.render[=[
<html>
<body>
{*markdown[[
#Hello, World
Testing Markdown.
]]*}
</body>
</html>
]=]
<html>
<body>
<h1>Hello, World</h1>
<p>Testing Markdown.</p>
</body>
</html>
You may also add config parameters that are documented in lua-resty-hoedown
project.
Say you want also to use SmartyPants:
local template = require "resty.template"
template.markdown = require "resty.hoedown"
template.render[=[
<html>
<body>
{*markdown([[
#Hello, World
Testing Markdown with "SmartyPants"...
]], { smartypants = true })*}
</body>
</html>
]=]
<html>
<body>
<h1>Hello, World</h1>
<p>Testing Markdown with “SmartyPants”…</p>
</body>
</html>
You may also want to add caching layer for your Markdowns, or a helper functions instead of placing
Hoedown library directly as a template helper function in template
.
Lua Server Pages or LSPs is similar to traditional PHP or Microsoft Active Server Pages (ASP)
where you can just place source code files in your document root (of your web server) and have
them processed by compilers of the respective languages (PHP, VBScript, JScript, etc.).
You can emulate quite closely this, sometimes called spaghetti-style of develoment, easily with
lua-resty-template
. Those that have been doing ASP.NET Web Forms development, know a concept
of Code Behind files. There is something similar, but this time we call it Layout in Front here
(you may include Lua modules with normal require
calls if you wish in LSPs). To help you
understand the concepts, let's have a small example:
http {
init_by_lua '
require "resty.core"
template = require "resty.template"
template.caching(false); -- you may remove this on production
';
server {
location ~ \.lsp$ {
default_type text/html;
content_by_lua 'template.render(ngx.var.uri)';
}
}
}
The above configuration creates a global template
variable in Lua environment (you may not want that).
We also created location to match all .lsp
files (or locations), and then we just render the template.
Let's imagine that the request is for index.lsp
.
{%
layout = "layouts/default.lsp"
local title = "Hello, World!"
%}
<h1>{{title}}</h1>
Here you can see that this file includes a little bit of a view (<h1>{{title}}</h1>
) in addition to some
Lua code that we want to run. If you want to have a pure code file with Layout in Front, then just don't
write any view code in this file. The layout
variable is already defined in views as documented else
where in this documentation. Now let's see the other files too.
<html>
{(include/header.lsp)}
<body>
{*view*}
</body>
</html>
Here we have a layout to decorate the index.lsp
, but we also have include here, so let's look at it.
<head>
<title>Testing Lua Server Pages</title>
</head>
Static stuff here only.
The final output will look like this:
<html>
<head>
<title>Testing Lua Server Pages</title>
</head>
<body>
<h1>Hello, World!</h1>
</body>
</html>
As you can see, lua-resty-template
can be quite flexibile and easy to start with. Just place
files under your document root and use the normal save-and-refresh style of development. The
server will automatically pick the new files and reload the templates (if the caching is turned
of) on save.
If you want to pass variables to layouts or includes you can add stuff to context table (in the
example below see context.title
):
{%
layout = "layouts/default.lsp"
local title = "Hello, World!"
context.title = 'My Application - ' .. title
%}
<h1>{{title}}</h1>
lua-resty-template
automatically caches (if caching is enabled) the resulting template functions
in template.cache
table. You can clear the cache by issuing template.cache = {}
.
- jd.com – Jingdong Mall (Chinese: 京东商城; pinyin: Jīngdōng Shāngchéng), formerly 360Buy, is a Chinese electronic commerce company
Please let me know if there are errors or old information in this list.
You may also look at these (as alternatives, or to mix them with lua-resty-template
):
- lemplate (https://github.com/openresty/lemplate)
- lua-resty-tags (https://github.com/bungle/lua-resty-tags)
- lua-resty-hoedown (https://github.com/bungle/lua-resty-hoedown)
- etlua (https://github.com/leafo/etlua)
- lua-template (https://github.com/dannote/lua-template)
- lua-resty-tmpl (https://github.com/lloydzhou/lua-resty-tmpl) (a fork of the lua-template)
- htmlua (https://github.com/benglard/htmlua)
- cgilua (http://keplerproject.github.io/cgilua/manual.html#templates)
- orbit (http://keplerproject.github.io/orbit/pages.html)
- lustache (https://github.com/Olivine-Labs/lustache)
- luvstache (https://github.com/james2doyle/luvstache)
- luaghetti (https://github.com/AterCattus/luaghetti)
- lust (https://github.com/weshoke/Lust)
- templet (http://colberg.org/lua-templet/)
- luahtml (https://github.com/TheLinx/LuaHTML)
- mixlua (https://github.com/LuaDist/mixlua)
- lutem (https://github.com/daly88/lutem)
- tirtemplate (https://github.com/torhve/LuaWeb/blob/master/tirtemplate.lua)
- groucho (https://github.com/hanjos/groucho)
- simple lua preprocessor (http://lua-users.org/wiki/SimpleLuaPreprocessor)
- slightly less simple lua preprocessor (http://lua-users.org/wiki/SlightlyLessSimpleLuaPreprocessor)
- ltp (http://www.savarese.com/software/ltp/)
- slt (https://code.google.com/p/slt/)
- slt2 (https://github.com/henix/slt2)
- view0 (https://bitbucket.org/jimstudt/view0)
- leslie (https://code.google.com/p/leslie/)
- fraudster (https://bitbucket.org/sphen_lee/fraudster)
- lua-haml (https://github.com/norman/lua-haml)
- lua-template (https://github.com/tgn14/Lua-template)
- hige (https://github.com/nrk/hige)
- mod_pLua (https://sourceforge.net/p/modplua/wiki/Home/)
- lapis html generation (http://leafo.net/lapis/reference.html#html-generation)
lua-resty-template
was originally forked from Tor Hveem's tirtemplate.lua
that he had extracted
from Zed Shaw's Tir web framework (http://tir.mongrel2.org/). Thank you Tor, and Zed for your earlier
contributions.
There is a small microbenchmark located here: https://github.com/bungle/lua-resty-template/blob/master/lib/resty/template/microbenchmark.lua
There is also a regression in LuaJIT that affects the results. If you want your LuaJIT patched against this, you need to merge this pull request: LuaJIT/LuaJIT#174.
Others have reported that in simple benchmarks running this template engine actually beats Nginx serving static files by a factor of three. So I guess this engine is quite fast.
local benchmark = require "resty.template.microbenchmark"
benchmark.run()
-- You may also pass iteration count (by default it is 1,000)
benchmark.run(100)
Here are some results from my laptop (2021 MacBook Pro, M1 Max)):
<lua|luajit|resty> -e 'require "resty.template.microbenchmark".run()'
Running 1000 iterations in each test
Parsing Time: 0.007365
Compilation Time: 0.022014 (template)
Compilation Time: 0.000103 (template, cached)
Execution Time: 0.020429 (same template)
Execution Time: 0.002542 (same template, cached)
Execution Time: 0.022314 (different template)
Execution Time: 0.003347 (different template, cached)
Execution Time: 0.021259 (different template, different context)
Execution Time: 0.003264 (different template, different context, cached)
Total Time: 0.102637
Running 1000 iterations in each test
Parsing Time: 0.008281
Compilation Time: 0.024388 (template)
Compilation Time: 0.000112 (template, cached)
Execution Time: 0.021825 (same template)
Execution Time: 0.002534 (same template, cached)
Execution Time: 0.018918 (different template)
Execution Time: 0.002217 (different template, cached)
Execution Time: 0.017005 (different template, different context)
Execution Time: 0.002164 (different template, different context, cached)
Total Time: 0.097444
Running 1000 iterations in each test
Parsing Time: 0.007645
Compilation Time: 0.020548 (template)
Compilation Time: 0.000104 (template, cached)
Execution Time: 0.019389 (same template)
Execution Time: 0.002644 (same template, cached)
Execution Time: 0.016816 (different template)
Execution Time: 0.002188 (different template, cached)
Execution Time: 0.015269 (different template, different context)
Execution Time: 0.002153 (different template, different context, cached)
Total Time: 0.086756
Running 1000 iterations in each test
Parsing Time: 0.003963
Compilation Time: 0.015456 (template)
Compilation Time: 0.000057 (template, cached)
Execution Time: 0.015738 (same template)
Execution Time: 0.001903 (same template, cached)
Execution Time: 0.015082 (different template)
Execution Time: 0.001752 (different template, cached)
Execution Time: 0.014412 (different template, different context)
Execution Time: 0.001758 (different template, different context, cached)
Total Time: 0.070121
LuaJIT 2.1.0-beta3 -- Copyright (C) 2005-2017 Mike Pall. http://luajit.org/
Running 1000 iterations in each test
Parsing Time: 0.002669
Compilation Time: 0.011761 (template)
Compilation Time: 0.000066 (template, cached)
Execution Time: 0.012112 (same template)
Execution Time: 0.001427 (same template, cached)
Execution Time: 0.022134 (different template)
Execution Time: 0.002520 (different template, cached)
Execution Time: 0.021685 (different template, different context)
Execution Time: 0.002381 (different template, different context, cached)
Total Time: 0.076755
Running 1000 iterations in each test
Parsing Time: 0.001615
Compilation Time: 0.010031 (template)
Compilation Time: 0.000029 (template, cached)
Execution Time: 0.011654 (same template)
Execution Time: 0.001203 (same template, cached)
Execution Time: 0.011206 (different template)
Execution Time: 0.001933 (different template, cached)
Execution Time: 0.010281 (different template, different context)
Execution Time: 0.001925 (different template, different context, cached)
Total Time: 0.049877
I have not yet compared the results against the alternatives.
The changes of every release of this module is recorded in Changes.md file.
- lua-resty-route — Routing library
- lua-resty-reqargs — Request arguments parser
- lua-resty-session — Session library
- lua-resty-validation — Validation and filtering library
Some things I and the community wishes to be added:
- Better debugging capabilities and better error messages
- Proper sandboxing
lua-resty-template
uses three clause BSD license (because it was originally forked from one that uses it).
Copyright (c) 2014 - 2022, Aapo Talvensaari
All rights reserved.
Redistribution and use in source and binary forms, with or without modification,
are permitted provided that the following conditions are met:
* Redistributions of source code must retain the above copyright notice, this
list of conditions and the following disclaimer.
* Redistributions in binary form must reproduce the above copyright notice, this
list of conditions and the following disclaimer in the documentation and/or
other materials provided with the distribution.
* Neither the name of the {organization} nor the names of its
contributors may be used to endorse or promote products derived from
this software without specific prior written permission.
THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR
ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
(INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.