gen-dart

webrpc-gen Dart templates

This repo contains the templates used by the webrpc-gen cli to code-generate webrpc Dart server and client code.

This generator, from a webrpc schema/design file will code-generate:

1. Client -- an isomorphic/universal Dart client to speak to a webrpc server using the provided schema. This client is compatible with any webrpc server language (ie. Go, nodejs, etc.).

2. Server -- not yet supported

Dependencies

The generated client requires the standard http package to function. Add it to your pubspec.yaml in your Dart or Flutter project

dependencies:
  # ... other dependencies
  http: ^1.1.0

Usage

webrpc-gen -schema=example.ridl -target=dart -client -out=./example.gen.dart

or

webrpc-gen -schema=example.ridl -target=github.com/webrpc/gen-dart@v0.17.2 -client -out=./example.gen.dart

or

webrpc-gen -schema=example.ridl -target=./local-templates-on-disk -client -out=./example.gen.dart

As you can see, the -target supports default dart, any git URI, or a local folder

Set custom template variables

Change any of the following values by passing -option="Value" CLI flag to webrpc-gen.

webrpc-gen -option	Description	Default value
-client	generate client code	unset (false)
-server	generate server code	unset (false)

Avoid using Records

Because Dart Records do not retain runtime information about their structure, it's impossible to reliably convert them to and from JSON. For this reason, we strongly advise against using Records in schema objects that have an any type (which maps to dynamic in Dart). In fact, you probably should not ever use the any type in your schema because it has ambigious structure which makes its structure meaningless on the other end of the wire. If you need a truly unstructured object, consider defining an internal convention and declaring it as a string in the schema.

Handle 64-bit numbers yourself

Numbers (double, num, int) in Dart can have up to 64 bits of width. However, if you are using Flutter and building for web, numbers are limited to ~53 bits. In brief, the consequence of this is that if your server sends a JSON number that is too big, it may be truncated - the value will change - according to the platform (language + architecture) being used. So, if you expected to use "wide" numbers (less than -(2^53 -1) or more than 2^53 - 1), you should package those numbers as a string and use the appropriate tools to handle them inside your app (such as BigInt in Dart).

CONTRIBUTE

Setup

Install Dart or Flutter. Ensure your version matches the sdk version specified in tests/pubspec.yaml.

Fork this repo.

Run the test scripts to ensure everything is set up correctly.

cd tests
./scripts/download.sh v0.17.2 .tmp/
./scripts/test.sh

Generated code will be written to tests/lib/client.dart

Make changes

Refer to the webrpc generator README for help on syntax. In brief, start in [main.go.tmpl] and traverse the template tree by going to the template file named by {{template "templateName" <args>}}, e.g. "templateName.go.tmpl".

(Update and) Run tests

Following the typical structure for a Dart package, tests are located in the aptly named tests/test/.

Working with a local version of webrpc?

If you are working with a local version of the base webrpc repo, build the generator and test server scripts there

cd path/to/webrpc
make build build-test

and pass the webrpc/bin directory to tests/scripts/test.sh

cd tests
./scripts/test.sh -r path/to/webrpc/bin

LICENSE

MIT LICENSE