feat: provide support for groupby

Signed-off-by: Muhammad Aaqil <aaqilcs102@gmail.com>

Author: aaqilniz

packages/filter/src/query.ts

@@ -230,6 +230,30 @@ export interface Filter<MT extends object = AnyObject> {
    * To include related objects
    */
   include?: InclusionFilter[];
+  /**
+   * return groupBy of
+   */
+  groupBy?: string[];
+  /**
+   * return sum of
+   */
+  sum?: string;
+  /**
+   * return min of
+   */
+  min?: string;
+  /**
+   * return max of
+   */
+  max?: string;
+  /**
+   * return avg of
+   */
+  avg?: string;
+  /**
+   * return count of
+   */
+  count?: string;
 }
 
 /**

packages/repository-json-schema/src/__tests__/unit/filter-json-schema.unit.ts

@@ -72,6 +72,12 @@ describe('getFilterJsonSchemaFor', () => {
       limit: 10,
       order: ['id DESC'],
       skip: 0,
+      sum: 'salary',
+      min: 'salary',
+      max: 'salary',
+      avg: 'salary',
+      count: 'salary',
+      groupBy: ['salary'],
     };
 
     expectSchemaToAllowFilter(customerFilterSchema, filter);
@@ -560,6 +566,9 @@ class Customer extends Entity {
   @property()
   name: string;
 
+  @property()
+  salary: number;
+
   @hasMany(() => Order)
   orders?: Order[];
 }

packages/repository-json-schema/src/filter-json-schema.ts

@@ -94,6 +94,32 @@ export function getFilterJsonSchemaFor(
       examples: [100],
     },
 
+    sum: {
+      type: 'string',
+      examples: ['column1'],
+    },
+    min: {
+      type: 'string',
+      examples: ['column1'],
+    },
+    max: {
+      type: 'string',
+      examples: ['column1'],
+    },
+    avg: {
+      type: 'string',
+      examples: ['column1'],
+    },
+    count: {
+      type: 'string',
+      examples: ['column1'],
+    },
+    groupBy: {
+      type: 'array',
+      items: {
+        type: 'string',
+      },
+    },
     skip: {
       type: 'integer',
       minimum: 0,
@@ -120,6 +146,9 @@ export function getFilterJsonSchemaFor(
   if (!excluded.includes('fields')) {
     properties.fields = getFieldsJsonSchemaFor(modelCtor, options);
   }
+  if (!excluded.includes('groupBy')) {
+    properties.fields = getGroupByJsonSchemaFor(modelCtor, options);
+  }
 
   // Remove excluded properties
   for (const p of excluded) {
@@ -235,3 +264,37 @@ export function getFieldsJsonSchemaFor(
 
   return schema;
 }
+
+export function getGroupByJsonSchemaFor(
+  modelCtor: typeof Model,
+  options: FilterSchemaOptions = {},
+): JsonSchema {
+  const schema: JsonSchema = {oneOf: []};
+  if (options.setTitle !== false) {
+    schema.title = `${modelCtor.modelName}.GroupBy`;
+  }
+
+  const properties = Object.keys(modelCtor.definition.properties);
+  const additionalProperties = modelCtor.definition.settings.strict === false;
+
+  schema.oneOf?.push({
+    type: 'object',
+    properties: properties.reduce(
+      (prev, crr) => ({...prev, [crr]: {type: 'boolean'}}),
+      {},
+    ),
+    additionalProperties,
+  });
+
+  schema.oneOf?.push({
+    type: 'array',
+    items: {
+      type: 'string',
+      enum: properties.length && !additionalProperties ? properties : undefined,
+      examples: properties,
+    },
+    uniqueItems: true,
+  });
+
+  return schema;
+}

packages/repository/src/repositories/legacy-juggler-bridge.ts

@@ -739,7 +739,7 @@ export class DefaultCrudRepository<
   }
 
   protected toEntity<R extends T>(model: juggler.PersistedModel): R {
-    return new this.entityClass(model.toObject()) as R;
+    return new this.entityClass(model.toObject({onlySchema: false})) as R;
   }
 
   protected toEntities<R extends T>(models: juggler.PersistedModel[]): R[] {

packages/rest/src/writer.ts

@@ -50,8 +50,19 @@ export function writeResultToResponse(
         // TODO(ritch) remove this, should be configurable
         // See https://github.com/loopbackio/loopback-next/issues/436
         response.setHeader('Content-Type', 'application/json');
+        let customResult = result;
+        if (result.length) {
+          customResult = [];
+          result.forEach((item: {[key: string]: Object[]}) => {
+            const org: {[key: string]: Object[]} = {};
+            Object.keys(item).forEach(key => {
+              org[key] = item[key];
+            });
+            customResult.push(org);
+          });
+        }
         // TODO(bajtos) handle errors - JSON.stringify can throw
-        result = JSON.stringify(result);
+        result = JSON.stringify(customResult);
       }
       break;
     default: