feat(repository): helper function for getting Model metadata

packages/repository/package.json

@@ -29,6 +29,8 @@
   },
   "dependencies": {
     "@loopback/context": "^4.0.0-alpha.23",
+    "@types/lodash": "^4.14.91",
+    "lodash": "^4.17.4",
     "loopback-datasource-juggler": "^3.9.2"
   },
   "files": [

packages/repository/src/decorators/metadata.ts

@@ -0,0 +1,41 @@
+import {InspectionOptions, MetadataInspector} from '@loopback/context';
+import {MODEL_KEY, MODEL_PROPERTIES_KEY} from '../';
+import {ModelDefinition, PropertyDefinition} from '../../index';
+import * as _ from 'lodash';
+
+export class ModelMetadataHelper {
+  /**
+   * A utility function to simplify retrieving metadata from a target model and
+   * its properties.
+   * @param target The class from which to retrieve metadata.
+   * @param options An options object for the MetadataInspector to customize
+   * the output of the metadata retrieval functions.
+   */
+  static getModelMetadata(target: Function, options?: InspectionOptions) {
+    const classDef = MetadataInspector.getClassMetadata(
+      MODEL_KEY,
+      target,
+      options,
+    );
+    const meta = new ModelDefinition(
+      Object.assign(
+        {
+          name: target.name,
+        },
+        classDef,
+      ),
+    );
+    if (_.isEmpty(_.keys(meta.properties))) {
+      meta.properties = Object.assign(
+        <PropertyDefinition>{},
+        MetadataInspector.getAllPropertyMetadata(
+          MODEL_PROPERTIES_KEY,
+          target.prototype,
+          options,
+        ),
+      );
+      MetadataInspector.defineMetadata(MODEL_KEY, meta, target);
+    }
+    return meta;
+  }
+}

packages/repository/src/index.ts

@@ -7,6 +7,7 @@ export * from './common-types';
 export * from './decorators/model';
 export * from './decorators/repository';
 export * from './decorators/relation';
+export * from './decorators/metadata';
 export * from './types';
 export * from './model';
 export * from './query';

packages/repository/test/unit/decorator/metadata.ts

@@ -0,0 +1,77 @@
+import {ModelMetadataHelper} from '../../../src';
+import {property, model, ModelDefinition, MODEL_KEY} from '../../..';
+import {expect} from '@loopback/testlab';
+import {MetadataInspector} from '@loopback/context';
+
+describe('Repository', () => {
+  describe('getAllClassMetadata', () => {
+    @model()
+    class Colour {
+      @property({})
+      rgb: string;
+    }
+    @model()
+    class Widget {
+      @property() id: number;
+      @property.array(Colour) colours: Colour[];
+    }
+
+    @model()
+    class Samoflange {
+      id: number;
+      name: string;
+      canRotate: boolean;
+    }
+
+    @model()
+    class Phlange {
+      @property() id: number;
+      @property() canFlap: boolean;
+      @property.array(Colour) colours: Colour[];
+    }
+
+    it('retrieves metadata for classes with @model', () => {
+      const meta = ModelMetadataHelper.getModelMetadata(Samoflange);
+      expect(meta).to.deepEqual(
+        new ModelDefinition({
+          name: 'Samoflange',
+          properties: {},
+          settings: new Map(),
+        }),
+      );
+    });
+
+    it('retrieves metadata for classes with @model and @property', () => {
+      const meta = ModelMetadataHelper.getModelMetadata(Widget);
+      expect(meta).to.deepEqual(
+        new ModelDefinition({
+          properties: {
+            id: {
+              type: Number,
+            },
+            colours: {
+              array: true,
+              type: Colour,
+            },
+          },
+          settings: new Map(),
+          name: 'Widget',
+        }),
+      );
+    });
+
+    it('returns existing properties instead of re-assembling them', () => {
+      const classMeta = MetadataInspector.getClassMetadata(
+        MODEL_KEY,
+        Phlange,
+      ) as ModelDefinition;
+      classMeta.properties = {
+        foo: {
+          type: String,
+        },
+      };
+      const meta = ModelMetadataHelper.getModelMetadata(Phlange);
+      expect(meta.properties).to.eql(classMeta.properties);
+    });
+  });
+});