/swagger-angular-generator

Generator of API layer in TypeScript for Angular 2+ apps

Primary LanguageTypeScriptMIT LicenseMIT

Purpose

Generate minimalistic TypeScript API layer for Angular with full type reflection of backend model.

What is generated

Services for back-end / API communication

  • connect to your API in no-time

Interfaces

  • request and response interfaces are created

Forms services for the PUT and POST methods

  • forms can be created by merely importing a service and using it in HTML templates (see below)

NGRX modules for endpoints (optional)

  • so that the server responses can be reached in the redux store
  • requests can be triggered by dispatching an action
Have a look at the demo-app generated files to get better understanding what is being generated.

Install

npm i swagger-angular-generator

Options

-h - show help

-s, --src - source directory

-d, --dest - destination directory, default: src/api

--no-store - do not generate the ngrx modules

-u, --swagger-URL-path - swagger URL path, where the swagger ui documentation can be found; default: /swagger, i.e. the resulting address would be http://example/swagger

-o, --omit-version - disables API version information to be generated in comments for each file

Use

Run generator

  1. get the swagger scheme (typically at http(s)://[server]/[app-path]/v2/api/api-docs)
  2. save it to json file in input directory and optionally format it for better diff
  3. run via
    1. directly ./node_modules/.bin/swagger-angular-generator
    2. as module swagger-angular-generator package, npm run generate 
      "script": {
  "generate": "swagger-angular-generator -s src/api/scheme.json -d src/api/generated"
  ...
}
    3. or programatically as a method invocation 
      import {generate} from 'swagger-angular-generator';
// or using CommonJS loader
const {generate} = require('swagger-angular-generator');

generate('conf/api/api-docs.json', 'src/api');

The resulting API layer contains the following structure in the destination directory:

  1. controllers directory stores services containing all API methods devided by controllers
  2. defs directory stores all response interfaces and enums
  3. store directory has modules, which contain associated form service and NGRX actions, reducers and effects
  4. model.ts file reexports all of them together for a simple access

When updating your code for new backend version, we recommend you to follow these steps:

  1. git diff the changes
  2. run tsc for immediate problems
  3. adjust the code, solve problems
  4. commit

Use

In order to consume generated model, follow the steps 1-9 in the following example to use generated API model.

API service usage in component

// 1. import used response interfaces
import {ItemDto, PageDto} from '[relative-path-to-destination-directory]/model';
// 2. import used API service and optionally param interfaces
import {DataService, MethodParams} from '[relative-path-to-destination-directory]/api/DataService';

@Component({
  ...
  // 3. make the service injectable (can be also imported in the module)
  providers: [DataService],
})
export class MyComponent implements OnInit {
  // 4. declare response object variables based on the generated API interfaces
  public items: ItemDto[] = [];
  public page: PageDto;

  // 5. declare request params based on the generated API interface (all params are passed together in one object)
  private params: MethodParams = {
    page: 0,
    size: 10,
    sort: ['name:asc']
  };

  // 6. inject the API service
  constructor(private dataService: DataService) {}

  public ngOnInit() {
    // 7. the returned observable is fully typed
    this.dataService
      .get(this.params)
      // 8. returned data are fully typed
      .subscribe(data => {
        // 9. assignments are type-checked
        this.items = data.content;
        this.page = data.page;
      });
  }
}

Usage of Forms services

  • the exampleFormService service is generated and holds the FormGroup definition that corresponds with the request data structure
  • Array-like structures use FormArrayExtended that extends native Angulars' FormArray and holds the definition of array item so new items can be created for data via .setValue() or empty via .createControl().
  • Map-like structures use FormMap that extends native Angulars' FormGroup and holds the definition of map value item so new items can be created for data via .setValue() or empty via .createControl().
  • there's a helper method safeSetValue() that sets the shape and data of all AbstractControl's ancestors and never fails (compatible data form the shape and are set, the rest is ignored).
  • use it in the template the following way
  • check the details in the generated test files, e.g. 
<form [formGroup]="exampleFormService.form" (ngSubmit)="sendForm()" class="full-width">
    <input type="text" name="email" placeholder="email"
           formControlName="email" />
    <button type="submit"
            [disabled]="exampleFormService.form.invalid">Save</button>
</form>
  • this is the corresponding component
@Component({
  selector: 'example-component',
  templateUrl: 'example-component.html',
})
export class ExampleComponent implements OnDestroy {
  constructor(public exampleFormService: ExampleFormService) {}
  sendForm() {...}
}
  • the generated service looks like this
export class ExampleFormService {
  form: FormGroup;
  constructor(private exampleService: ExampleService) {
    this.form = new FormGroup({
      email: new FormControl(undefined, [Validators.email, Validators.required]),
    });
  }
}

NGRX workflow with generated modules, actions, effects, reducers and form services

Import the generated module
@NgModule({
  imports: [
    ...,
    ExampleModule,
    ...,
  ],
})
export class YourModule {}
  • the generated module looks like this
@NgModule({
  imports: [
    FormsSharedModule,
    NgrxStoreModule.forFeature(selectorName, ExampleReducer),
    NgrxEffectsModule.forFeature([ExampleEffects]),
  ],
  providers: [
    ExampleService,
    ExampleFormService,
  ],
})
export class ExampleModule {}
Component (created by you)

In the component, send the above created form via sendForm() method. Notice the way a generated anction is dispatched.

import {Component, OnDestroy} from '@angular/core';
import {Store} from '@ngrx/store';
import {takeUntil} from 'rxjs/operators';
import {Subject} from 'rxjs/Subject';
import {ExampleFormService} from '../../generated/store/example/exampleModule/example.service';
import {Start as ExampleStart} from '../../generated/store/example/exampleModule/states/actions';
import {AppState} from '../states/exmaple.models';

@Component({
  selector: 'example-component',
  templateUrl: 'example-component.html',
})
export class ExampleComponent implements OnDestroy {

  constructor(
    public exampleFormService: ExampleFormService,
    private store: Store<AppState>,
  ) {}

  sendForm() {
    this.store.dispatch(new ExampleStart(this.exampleFormService.form.value));
  }

  ngOnDestroy() {
    this.ngDestroy.next();
    this.ngDestroy.complete();
  }
}
Effect (generated)
  • the dispatched method is intercepted by an effect which calls the API via the generated API service
  • upon success, a Success action is dispatched (payload is the server response data)
  • upon error, an Error action is dispatched (payload is the error message sent from the server)
@Injectable()
export class ExampleEffects {
  @Effect()
  CreateProductCategory = this.storeActions.ofType<actions.Start>(actions.Actions.START).pipe(
    switchMap((action: actions.Start) => this.exampleService.exampleEndpointMethod(action.payload)
      .pipe(
        map(result => new actions.Success(result)),
        catchError((error: HttpErrorResponse) => of(new actions.Error(error.message))),
      ),
    ),
  );

  constructor(
    private storeActions: Actions,
    private adminproductService: AdminProductService,
  ) {}
}
Reducer (generated)
  • the reducer catches the Success / Error actions dispatched by the generated effect and stores the payloads to the store
export interface ExampleState {
  data: __model.ExampleServerResponseInterface;
  loading: boolean;
  error: string;
}

export const initialExampleState: ExampleState = {
  data: null,
  loading: false,
  error: null,
};

export const selectorName = 'Example';
export const getExampleSelector = createFeatureSelector<ExampleState>(selectorName);

export function ExampleReducer(
  state: ExampleState = initialExampleState,
  action: actions.ExampleAction): ExampleState {
  switch (action.type) {
    case actions.Actions.START: return {...state, loading: true, error: null};
    case actions.Actions.SUCCESS: return {...state, data: action.payload, loading: false};
    case actions.Actions.ERROR: return {...state, error: action.payload, loading: false};
    default: return state;
  }
}
Component (again)
  • the data can be retrieved by subscribing to the store
ngOnInit() {
    this.exampleState = this.store.pipe(
      takeUntil(this.ngDestroy),
      select(getExampleSelector));
    // OR
    this.data = this.store.select(s => ExampleState.data)
    this.loading = this.store.select(s => ExampleState.loading)
    this.error = this.store.select(s => ExampleState.error)
}

Assumptions / limitations

  1. swagger file is in version 2 format, it must be json
  2. each endpoint must have a tags attribute defined. In addition, there must be exactly one tag defined. The http methods are grouped to services based on the tags, i.e. if two methods have tag "order", both will be generated inside Order.ts
  3. get and delete methods do not contain body
  4. swagger file should contain values for the keys host and basePath so that each generated service method can contain a link to the swagger UI method reference, e.g. http://example.com/swagger/swagger-ui.html#!/Order/Order
  5. definitions section in swagger file does not contain types with inline definitions, i.e. only named subtypes work

Usage of NGRX modules

Development

  • at least Node.js 8 is needed

Docker image

  1. docker build . -t swagger-angular-generator
  2. docker run -u $(id -u) -it -v "$PWD":/code swagger-angular-generator bash
  3. npm i
  4. npm run install:demo

Testing

How the testing works

  • tests are written in the demo-app
  • the test swagger files can be found in demo-app/client/test-swaggers
  • upon these swagger files, interfaces and services are generated
  • the generated services are manually imported to the app.module.ts
  • unit tests can be found in demo-app/client/src/tests

Running the tests

To run client tests in interactive mode:

  1. cd demo-app/client
  2. npm test

Pull requests are welcome!

Please do the following before making a PR:

  1. Build the app and regenerate testing files via npm run build.
  2. Check test pass via npm test.
  3. Check files lint via npm run lint.