feat(core): add helper function for override schema of models

add helper function for override schema of models

gh-86

Author: Sunny Tyagi

packages/core/src/__tests__/unit/build-schema.unit.ts

@@ -0,0 +1,57 @@
+import {MetadataInspector} from '@loopback/context';
+import {getModelSchemaRef, JsonSchemaOptions} from '@loopback/openapi-v3';
+import {expect} from '@loopback/testlab';
+import {
+  getModelSchemaRefSF,
+  OVERRIDE_MODEL_SCHEMA_KEY,
+} from '../../build-schema'; // adjust the path accordingly
+
+describe('getModelSchemaRefSF', () => {
+  class SampleModel {
+    name: string;
+    age: number;
+  }
+
+  afterEach(() => {
+    // Clear metadata between tests
+    MetadataInspector.defineMetadata(
+      OVERRIDE_MODEL_SCHEMA_KEY,
+      undefined,
+      SampleModel,
+    );
+  });
+
+  it('returns schema ref using the original model when no override metadata is present', () => {
+    const schema = getModelSchemaRefSF(SampleModel);
+    const expectedSchema = getModelSchemaRef(SampleModel);
+    expect(schema).to.deepEqual(expectedSchema);
+  });
+
+  it('returns schema ref using the overridden model when metadata is set', () => {
+    class OverriddenModel {
+      title: string;
+    }
+
+    // Set override metadata
+    MetadataInspector.defineMetadata(
+      OVERRIDE_MODEL_SCHEMA_KEY,
+      OverriddenModel,
+      SampleModel,
+    );
+
+    const schema = getModelSchemaRefSF(SampleModel);
+    const expectedSchema = getModelSchemaRef(OverriddenModel);
+    expect(schema).to.deepEqual(expectedSchema);
+  });
+
+  it('respects json schema options passed to the function', () => {
+    const options: JsonSchemaOptions<SampleModel> = {
+      title: 'CustomTitle',
+      optional: ['age'],
+    };
+
+    const schema = getModelSchemaRefSF(SampleModel, options);
+    const expectedSchema = getModelSchemaRef(SampleModel, options);
+    expect(schema).to.deepEqual(expectedSchema);
+  });
+});

packages/core/src/build-schema.ts

@@ -0,0 +1,31 @@
+import {MetadataAccessor, MetadataInspector} from '@loopback/context';
+import {
+  JsonSchemaOptions,
+  SchemaRef,
+  getJsonSchemaRef,
+  jsonToSchemaObject,
+} from '@loopback/openapi-v3';
+
+/**
+ * Metadata key used to set or retrieve repository JSON Schema
+ */
+
+export const OVERRIDE_MODEL_SCHEMA_KEY = MetadataAccessor.create<
+  Function,
+  ClassDecorator
+>('sourceloop:override-model-schema');
+
+export function getModelSchemaRefSF<T extends object>(
+  modelCtor: Function & {prototype: T},
+  options?: JsonSchemaOptions<T>,
+): SchemaRef {
+  const cached = MetadataInspector.getClassMetadata<Function & {prototype: T}>(
+    OVERRIDE_MODEL_SCHEMA_KEY,
+    modelCtor,
+    {
+      ownMetadataOnly: true,
+    },
+  );
+  const jsonSchema = getJsonSchemaRef(cached ?? modelCtor, options);
+  return jsonToSchemaObject(jsonSchema) as SchemaRef;
+}

packages/core/src/index.ts

@@ -3,6 +3,7 @@
 // This software is released under the MIT License.
 // https://opensource.org/licenses/MIT
 export * from './adapters';
+export * from './build-schema';
 export * from './casbin-secure-sequence';
 export * from './command';
 export * from './component';