Graphql Generator

These days, GraphQL is getting popular and many companies have adopted it to build their API and github.com is one of them. In most cases, developer will write their schema code with their favorite language and then wire in the business logic into the resolvers. Recently there is a IDL defined by the community; although it is not a standard yet, there are a lot of big players that supprot it. Our generator can utilize the GraphQL IDL or just scaffold a project with simple Hello World for developer to extend. Either way, you need to wire in your business logic after the project is generated.

Input

Model

There are two different ways to generate projects with light-graphql-4j generator.

With IDL - Pass in IDL and you need to wire in your backend logic.
Without IDL - A simple Hello World graphql application runnable as starting point.

NOTE: IDL is not currently part of the formal graphql spec. The implementation in this library is based off the reference implementation. However plenty of code out there is based on this IDL syntax and hence you can be fairly confident that you are building on solid technology ground.

We recommend using IDL. For more information about IDL, please check here

Config

Field Name	Description
name	used in generated pom.xml for project version
version	used in generated pom.xml for project version
groupID	used in generated pom.xml for project groupId
artifactId	used in generated pom.xml for project artifactId
schemaPackage	the package name for generated schema class
schemaClass	the generated schema class name
overwriteSchemaClass	controls if the schema class needs to be generated or not. For new project, it should be true. If you want to upgrade the framework to a new version but don’t want to overwrite the updated schema class, then set it to false and regenerate to the same folder.
httpPort	the http port number the server is listening to if it is enabled.
enableHttp	the flag to control if http is enabled or not.
httpsPort	the https port number the server is listening to if it is enabled.
enableHttps	the flag to control if https is enabled or not.
supportDb	to control if db connection pool will be setup in service.yml and db dependencies are included in pom.xml
dbInfo	section is the database connection pool configuration info.
supportH2ForTest	a flag to control if H2 code is included in the test server and H2 jar is included in pom.mxl
supportClient	a flag to control if client module is included in the generated project to call other services.

Here is an example of config.json for light-graphql-4j generator.

{
  "name": "starwars",
  "version": "1.0.1",
  "groupId": "com.networknt",
  "artifactId": "starwars",
  "schemaPackage": "com.networknt.starwars.schema",
  "schemaClass": "StarWarsSchema",
  "overwriteSchemaClass": true,
  "httpPort": 8080,
  "enableHttp": true,
  "httpsPort": 8443,
  "enableHttps": false,
  "enableRegistry": false,
  "supportDb": true,
  "dbInfo": {
    "name": "mysql",
    "driverClassName": "com.mysql.jdbc.Driver",
    "jdbcUrl": "jdbc:mysql://mysqldb:3306/oauth2?useSSL=false",
    "username": "root",
    "password": "my-secret-pw"
  },
  "supportH2ForTest": false,
  "supportClient": false
}

In most cases, developers will only update schema class and other depending classes in schema package.

Usage

Java Command line

You can download or build the codegen-cli command line jar.

Without IDL

First, let’s generate schema as “Hello World” as a starting point so that developers can update it to manually code their schema class.

The following command will create a sample GraphQL server project in the /tmp/graphql folder.

Working directory: light-codegen

java -jar codegen-cli/target/codegen-cli.jar -f light-graphql-4j -o /tmp/graphql -c light-graphql-4j/src/test/resources/config.json

And to build and run the server:

cd /tmp/graphql
mvn clean install exec:exec

Open your browser and point to http://localhost:8080/graphql for the graphiql interface to show up in your browser.

With IDL

Let’s generate a graphql project with IDL. There is a starwars IDL in our test folder.

Working directory: light-codegen

java -jar codegen-cli/target/codegen-cli.jar -f light-graphql-4j -o /tmp/graphql -m light-graphql-4j/src/test/resources/schema.graphqls -c light-graphql-4j/src/test/resources/config.json

The generated project can be built but not runnable as there is no backend code wired in yet. Take a look at the schema class and make the change in the commented section to complete it.

Docker Command Line

The following command is using docker to generate light-graphql-4j into /tmp/light-codegen/graphql folder

docker run -it -v ~/networknt/light-codegen/light-graphql-4j/src/test/resources:/light-api/input -v /tmp/light-codegen:/light-api/out networknt/light-codegen -f light-graphql-4j -c /light-api/input/config.json -o /light-api/out/graphql

On Linux environment, the generated code might belong to root:root and you need to change the owner to yourself before building it.

Let’s change the owner and build the service

cd /tmp/light-codegen
sudo chown -R steve:steve graphql
cd graphql
mvn clean install exec:exec

To test the server, please follow the instructions above in the utility command line.

Docker Scripting

git clone [email protected]:networknt/model-config.git
cd model-config
./generate.sh light-graphql-4j ~/networknt/model-config/graphql/helloworld /tmp/graphql

Now you should have a project generated in /tmp/graphql/generated

Codegen Site

The service API is ready. We are working on the UI with a generation wizard.