feat: provide support for groupby

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

lib/sql.js

@@ -1260,6 +1260,15 @@ SQLConnector.prototype.buildFields = function(model, data, excludeIds) {
   return this._buildFieldsForKeys(model, data, keys, excludeIds);
 };
 
+/**
+ * Build a part of query for group by
+ * @param {String[]} groupBy Array of column names to be grouped by
+ * @returns a part of query for group by as a string
+ */
+SQLConnector.prototype.buildGroupBy = function(groupBy) {
+  return 'GROUP BY ' + groupBy.join(',');
+};
+
 /**
  * Build an array of fields for the database operation from data array
  * @param {String} model Model name
@@ -1439,7 +1448,25 @@ SQLConnector.prototype.buildSelect = function(model, filter, options) {
     }
   }
 
+  let extraSelect = '';
+  if (filter.sum) {
+    extraSelect = `SUM(${filter.sum}) as sumOf${filter.sum}, `;
+  }
+  if (filter.count) {
+    extraSelect += `COUNT(${filter.count}) as countOf${filter.count}, `;
+  }
+  if (filter.avg) {
+    extraSelect += `AVG(${filter.avg}) as avgOf${filter.avg}, `;
+  }
+  if (filter.min) {
+    extraSelect += `MIN(${filter.min}) as minOf${filter.min}, `;
+  }
+  if (filter.max) {
+    extraSelect += `MAX(${filter.max}) as maxOf${filter.max}, `;
+  }
+
   let selectStmt = new ParameterizedSQL('SELECT ' +
+    extraSelect +
     this.buildColumnNames(model, filter) +
     ' FROM ' + this.tableEscaped(model));
 
@@ -1449,6 +1476,10 @@ SQLConnector.prototype.buildSelect = function(model, filter, options) {
       selectStmt.merge(whereStmt);
     }
 
+    if (filter.groupBy) {
+      selectStmt.merge(this.buildGroupBy(filter.groupBy));
+    }
+
     if (filter.order) {
       selectStmt.merge(this.buildOrderBy(model, filter.order));
     }
@@ -1510,7 +1541,23 @@ SQLConnector.prototype.all = function find(model, filter, options, cb) {
     }
 
     const objs = data.map(function(obj) {
-      return self.fromRow(model, obj);
+      const object = self.fromRow(model, obj);
+      if (obj[`sumOf${filter.sum}`]) {
+        object[`sumOf${filter.sum}`] = obj[`sumOf${filter.sum}`];
+      }
+      if (obj[`countOf${filter.count}`]) {
+        object[`countOf${filter.count}`] = obj[`countOf${filter.count}`];
+      }
+      if (obj[`avgOf${filter.avg}`]) {
+        object[`avgOf${filter.avg}`] = obj[`avgOf${filter.avg}`];
+      }
+      if (obj[`minOf${filter.min}`]) {
+        object[`minOf${filter.min}`] = obj[`minOf${filter.min}`];
+      }
+      if (obj[`maxOf${filter.max}`]) {
+        object[`maxOf${filter.max}`] = obj[`maxOf${filter.max}`];
+      }
+      return object;
     });
     if (filter && filter.include) {
       self.getModelDefinition(model).model.include(

test/sql.test.js

@@ -256,6 +256,11 @@ describe('sql connector', function() {
     expect(orderBy).to.eql('ORDER BY `NAME`');
   });
 
+  it('builds group by with one field', function() {
+    const groupBy = connector.buildGroupBy(['id']);
+    expect(groupBy).to.eql('GROUP BY id');
+  });
+
   it('builds order by with two fields', function() {
     const orderBy = connector.buildOrderBy('customer', ['name', 'vip']);
     expect(orderBy).to.eql('ORDER BY `NAME`,`VIP`');
@@ -366,6 +371,28 @@ describe('sql connector', function() {
     });
   });
 
+  it('builds SELECT with groupBy, sum, avg, min, max & count', function() {
+    const sql = connector.buildSelect('customer',
+      {
+        groupBy: ['name'],
+        sum: 'salary',
+        avg: 'salary',
+        min: 'salary',
+        max: 'salary',
+        count: 'salary',
+      });
+    expect(sql.toJSON()).to.eql({
+      sql: 'SELECT SUM(salary) as sumOfsalary, COUNT(salary) as countOfsalary,' +
+      ' AVG(salary) as avgOfsalary, MIN(salary) as minOfsalary,' +
+      ' MAX(salary) as maxOfsalary, `NAME`,`middle_name`,`LASTNAME`,`VIP`,' +
+      '`primary_address`,`TOKEN`,`ADDRESS`' +
+      ' FROM `CUSTOMER`' +
+      ' GROUP BY name' +
+      ' ORDER BY `NAME`',
+      params: [],
+    });
+  });
+
   it('builds INSERT', function() {
     const sql = connector.buildInsert('customer', {name: 'John', vip: true});
     expect(sql.toJSON()).to.eql({