feat: add capability for insert multiple rows in single query

Signed-off-by: Samarpan Bhattacharya <this.is.samy@gmail.com>

.gitignore

@@ -13,3 +13,6 @@
 node_modules
 checkstyle.xml
 loopback-connector-*.tgz
+.nyc_output
+coverage
+.vscode

lib/sql.js

@@ -46,6 +46,14 @@ SQLConnector.Transaction = Transaction;
  */
 SQLConnector.prototype.relational = true;
 
+/**
+ * Set the multiInsertSupported property to indicate if multiple value insert SQL dialect is supported or not
+ * This can be overridden by derived connectors to allow `insert multiple values` dialect for createAll
+ * By default, it is set to false for backward compatibility
+ * @type {boolean}
+ */
+SQLConnector.prototype.multiInsertSupported = false;
+
 /**
  * Invoke a prototype method on the super class
  * @param {String} methodName Method name
@@ -540,6 +548,53 @@ SQLConnector.prototype.buildInsert = function(model, data, options) {
   return this.parameterize(insertStmt);
 };
 
+/**
+ * Build INSERT SQL statement for multiple values
+ * @param {String} model The model name
+ * @param {Object} data The array of model data object
+ * @param {Object} options The options object
+ * @returns {Object} The ParameterizedSQL Object with INSERT SQL statement
+ */
+SQLConnector.prototype.buildInsertAll = function(model, data, options) {
+  if (!this.multiInsertSupported) {
+    debug('multiple value insert SQL dialect is not supported by this connector');
+    // return immediately if multiInsertSupported=false in connector
+    return null;
+  }
+  const fieldsArray = this.buildFieldsFromArray(model, data);
+  if (fieldsArray.length === 0) {
+    debug('no fields found for insert query');
+    // return immediately if no fields found
+    return null;
+  }
+  const insertStmt = this.buildInsertInto(model, fieldsArray[0], options);
+
+  for (let i = 0; i < fieldsArray.length; i++) {
+    const columnValues = fieldsArray[i].columnValues;
+    const isLast = (i === (fieldsArray.length - 1));
+    const isFirst = (i === 0);
+
+    if (columnValues.length) {
+      const values = ParameterizedSQL.join(columnValues, ',');
+      // Multi value query.
+      // This lets multiple row insertion in single query
+      values.sql = (isFirst ? 'VALUES ' : '') +
+        '(' + values.sql + ')' +
+        (isLast ? '' : ',');
+      insertStmt.merge(values);
+    } else {
+      // Insert default values if no values provided
+      insertStmt.merge(this.buildInsertDefaultValues(model, data, options));
+    }
+  }
+
+  const returning = this.buildInsertReturning(model, data, options);
+  if (returning) {
+    insertStmt.merge(returning);
+  }
+  return this.parameterize(insertStmt);
+};
+
 /**
  * Execute a SQL statement with given parameters.
  *
@@ -630,6 +685,34 @@ SQLConnector.prototype.create = function(model, data, options, callback) {
   });
 };
 
+/**
+ * Create multiple data models in a single insert query
+ * Works only if `multiInsertSupported` is set to true for the connector
+ *
+ * @param {String} model The model name
+ * @param {Object} data The model instances data
+ * @param {Object} options Options object
+ * @param {Function} [callback] The callback function
+ */
+SQLConnector.prototype.createAll = function(model, data, options, callback) {
+  const self = this;
+  const stmt = this.buildInsertAll(model, data, options);
+  if (!stmt) {
+    debug('empty SQL statement returned for insert into multiple values');
+    callback(new Error(
+      g.f('empty SQL statement returned for insert into multiple values'),
+    ));
+  }
+  this.execute(stmt.sql, stmt.params, options, function(err, info) {
+    if (err) {
+      callback(err);
+    } else {
+      const insertedId = self.getInsertedId(model, info);
+      callback(err, insertedId);
+    }
+  });
+};
+
 /**
  * Save the model instance into the database
  * @param {String} model The model name
@@ -1177,6 +1260,24 @@ SQLConnector.prototype.buildFields = function(model, data, excludeIds) {
   return this._buildFieldsForKeys(model, data, keys, excludeIds);
 };
 
+/**
+ * Build an array of fields for the database operation from data array
+ * @param {String} model Model name
+ * @param {Object} data Array of Model data object
+ * @param {Boolean} excludeIds Exclude id properties or not, default to false
+ * @returns {[{names: Array, values: Array, properties: Array}]}
+ */
+SQLConnector.prototype.buildFieldsFromArray = function(model, data, excludeIds) {
+  const fields = [];
+  if (data.length > 0) {
+    const keys = Object.keys(data[0]);
+    for (let i = 0; i < data.length; i++) {
+      fields.push(this._buildFieldsForKeys(model, data[i], keys, excludeIds));
+    }
+  }
+  return fields;
+};
+
 /**
  * Build an array of fields for the replace database operation
  * @param {String} model Model name

test/sql.test.js

@@ -514,4 +514,38 @@ describe('sql connector', function() {
     expect(function() { runExecute(); }).to.not.throw();
     ds.connected = true;
   });
+
+  it('should build INSERT for multiple rows if multiInsertSupported is true', function() {
+    connector.multiInsertSupported = true;
+    const sql = connector.buildInsertAll('customer', [
+      {name: 'Adam', middleName: 'abc', vip: true},
+      {name: 'Test', middleName: null, vip: false},
+    ]);
+    expect(sql.toJSON()).to.eql({
+      sql:
+      'INSERT INTO `CUSTOMER`(`NAME`,`middle_name`,`VIP`) VALUES ($1,$2,$3), ($4,$5,$6)',
+      params: ['Adam', 'abc', true, 'Test', null, false],
+    });
+  });
+
+  it('should return null for INSERT multiple rows if multiInsertSupported is false',
+    function() {
+      connector.multiInsertSupported = false;
+      const sql = connector.buildInsertAll('customer', [
+        {name: 'Adam', middleName: 'abc', vip: true},
+        {name: 'Test', middleName: null, vip: false},
+      ]);
+      // eslint-disable-next-line no-unused-expressions
+      expect(sql).to.be.null;
+    });
+
+  it('should return null for INSERT multiple rows if multiInsertSupported not set',
+    function() {
+      const sql = connector.buildInsertAll('customer', [
+        {name: 'Adam', middleName: 'abc', vip: true},
+        {name: 'Test', middleName: null, vip: false},
+      ]);
+      // eslint-disable-next-line no-unused-expressions
+      expect(sql).to.be.null;
+    });
 });