[R] Issues with R Codegen Clients

[cannin]

I tried to make a new API package using the following with code pulled on September 18. :

java -jar modules/swagger-codegen-cli/target/swagger-codegen-cli.jar -i http://petstore.swagger.io/v2/swagger.json -l r -o /tmp/test

Below are a number of suggestions and bugs:

Minor Issue 1: Include Installation Instructions

This would be useful in the README.md.

Set up to use CRAN package repository

setRepositories(ind=1:6)
options(repos="http://cran.rstudio.com/")
if(!require(devtools)) { install.packages("devtools") }

Install package

library(devtools)
install(".")

First Bug: The above doesn't work.

The code needs a NAMESPACE file in the top directory. Any function that had an @export in the template will need to be represented in the NAMESPACE file as below:

export(func1)
export(func2)

Second Bug: Syntax issue

The NAMESPACE can be generated in R, so I tried to do that, but came across this issue when building the NAMESPACE file using roxygen (http://r-pkgs.had.co.nz/namespace.html):

Error in parse(text = lines, n = -1, srcfile = srcfile) :
/tmp/test/R/ApiResponse.r:47:39: unexpected symbol
46: ApiResponseObject <- jsonlite::fromJSON(ApiResponseJson)
47: self$code <- ApiResponseObject$code

The backtick is in the wrong place, it should be after the dollar sign. Also, the backtick is probably not needed at all unless spaces can appear in the strings.

Third Bug: Use API name in DESCRIPTION

This line:

Package: swagger

will end up conflicting if multiple Swagger packages are installed. Libraries in R are loaded as library(swagger) using the package string. Can "title":"Swagger Petstore" be grabbed instead? The space won't work. Some options: CamelCase or just turn it into all lowercase replacing spaces with underscores or dashes?

Background:

• http://r-pkgs.had.co.nz/package.html (names should be unique)
• https://cran.r-project.org/doc/manuals/r-release/R-exts.html#The-DESCRIPTION-file ([Package] should contain only (ASCII) letters, numbers and dot, have at least two characters and start with a letter and not end in a dot.)

Minor Issue 2:

What is git_push.sh for? Is it necessary? Can it be removed from the code generation?

Fourth Bug: Duplicated code

Response and Element classes are duplicated in several files.

[wing328]

@cannin for the improvement in README.md, do you mind submitting a PR? A good starting point is https://github.com/swagger-api/swagger-codegen/blob/master/modules/swagger-codegen/src/main/resources/r/README.mustache

cc @ramnov

[jschelbert]

I've created a PR for some of the errors. There seemed to be some smaller bugs in the mustache files. Hopefully, these are now fixed. However, the issue about NAMESPACE and DESCRIPTION remain.

[albsantosdel]

I have tested this version and most of the errors identified by @cannin have been solved. It is still necessary to create the NAMESPACE file but swagger-codegen generates valid R code. I found though several errors:

I generated the R code for the Pet shop example (http://petstore.swagger.io/) using:
java -jar ../swagger-codegen/modules/swagger-codegen-cli/target/swagger-codegen-cli.jar generate -i http://petstore.swagger.io/v2/swagger.json -l r -o .

Installed the generated R package:

install.packages('devtools')
library(devtools)
install('.')
devtools::document() #Generate NAMESPACE file

Run "Get user by user name" example (http://petstore.swagger.io/#/user/getUserByName):

library(swagger)
userApi = swagger::UserApi$new() 
user = userApi$get_user_by_name(username = "user1")
user$content$id
user$content$username
user$content$email

Response:
Error in user$new()$fromJSON(httr::content(resp, "text", encoding = "UTF-8"), :
unused argument (simplifyVector = FALSE)

I deleted this argument from the generated R code (UserApi.r) and run again:
Response:
"API client error"

I debugged the actual GET request sent and the path ('/user/') seems to be missing:

resp <- httr::GET(paste0(self$basePath,username),
          httr::add_headers("User-Agent" = self$userAgent, 
				"content-type" = "application/xml"))

I believe the path needs to be added to paste0() here:
https://github.com/jschelbert/swagger-codegen/blob/master/modules/swagger-codegen/src/main/resources/r/api.mustache#L17

I added manually the right path (UserApi.r:81):

resp <- httr::GET(paste0(self$basePath,"/user/",username),
          httr::add_headers("User-Agent" = self$userAgent, "content-type" = "application/xml"))

Response:
I should have obtained a User object but instead I got an integer:

user
[1] 0

The generated code seems not to work as a one-liner here (UserApi.r:86):
result <- User$new()$fromJSON(httr::content(resp, "text", encoding = "UTF-8"))
Corresponds to:
https://github.com/jschelbert/swagger-codegen/blob/master/modules/swagger-codegen/src/main/resources/r/api.mustache#L45

If instead it is divided into 2, it works:

result <- User$new()
result$fromJSON(httr::content(resp, "text", encoding = "UTF-8"))

Response:

user$content$id
[1] 0
user$content$username
[1] "user1"
user$content$email
[1] "string"

[wing328]

@albsantosdel thanks for testing the fix. I've merged it into master given that it fixes most of the issues.

[wing328]

@albsantosdel for the missing path issue with https://github.com/jschelbert/swagger-codegen/blob/master/modules/swagger-codegen/src/main/resources/r/api.mustache#L17, I think we need to revise it with {{path}} as follows:

      resp <- httr::{{httpMethod}}(paste0(self$basePath, "{{path}}", {{#pathParams}}, {{paramName}}{{/pathParams}}),

Would you have time to submit a PR with the fix (together with the fix for https://github.com/jschelbert/swagger-codegen/blob/master/modules/swagger-codegen/src/main/resources/r/api.mustache#L45)?

[wing328]

@albsantosdel Looks like #6571 will fix the issues you encountered. Do you mind testing the PR when you've time?

git checkout -b brnleehng-fix/r-mustache-templates master
git pull https://github.com/brnleehng/swagger-codegen.git fix/r-mustache-templates

cc @brnleehng

[brnleehng]

The url path needs string replacement instead of appending at the end.

For example, /{{path parameter}}/path will not work for the url path. I've updated my PR for this use case #6571

[albsantosdel]

I have tested the PR #6571 (without the fixes done few minutes ago) and I found several issues:

1. Generated DESCRIPTION file is not correct:
Response:

• installing source package ‘Swagger Petstore’ ...
  Error : Invalid DESCRIPTION file

Malformed package name

See section 'The DESCRIPTION file' in the 'Writing R Extensions'
manual.

ERROR: installing package DESCRIPTION failed for package ‘Swagger Petstore’

• removing ‘/Library/Frameworks/R.framework/Versions/3.4/Resources/library/Swagger Petstore’
  Error: Command failed (1)

I went back to Package: {{{packageName}}} and it worked just fine.

2. user$apiClient is NULL:
In UserApi, apiClient is equal to NULL and never initialized, so when running the test you get an error:

library(swagger)
userApi = swagger::UserApi$new() 
user = userApi$get_user_by_name(username = "testUser")

Response:
Error in userApi$get_user_by_name(username = "user1") :
attempt to apply non-function

To solve the error, I modified the generated code to include the initialization (UserApi.r:52):
apiClient = ApiClient$new()

3. When the previous error was solved, the request was sent but I got

Response:
"API client error"

The generated url is incorrect ("http://petstore.swagger.io/v2/User/testUser") because the path is "User" instead of "user". If this is changed in the generated code (UserApi.r: 51) the test example works:

library(swagger)
userApi = swagger::UserApi$new() 
user = userApi$get_user_by_name(username = "testUser")
class(user)
user$content$id
user$content$username
user$content$email