feat(model): add countDocuments()

Fix #6643
Re: mongodb/node-mongodb-native#1774

Author: vkarpov15

lib/model.js

@@ -1688,6 +1688,38 @@ Model.findOne = function findOne(conditions, projection, options, callback) {
   return mq.findOne(conditions, callback);
 };
 
+/**
+ * Counts number of matching documents in a database collection. This method
+ * is deprecated, use `countDocuments()` instead.
+ *
+ * ####Example:
+ *
+ *     Adventure.count({ type: 'jungle' }, function (err, count) {
+ *       if (err) ..
+ *       console.log('there are %d jungle adventures', count);
+ *     });
+ *
+ * @deprecated
+ * @param {Object} conditions
+ * @param {Function} [callback]
+ * @return {Query}
+ * @api public
+ */
+
+Model.countDocuments = function count(conditions, callback) {
+  if (typeof conditions === 'function') {
+    callback = conditions;
+    conditions = {};
+  }
+
+  // get the mongodb collection object
+  const mq = new this.Query({}, {}, this, this.collection);
+
+  callback = this.$wrapCallback(callback);
+
+  return mq.countDocuments(conditions, callback);
+};
+
 /**
  * Counts number of matching documents in a database collection.
  *

lib/query.js

@@ -1748,7 +1748,33 @@ Query.prototype._count = function(callback) {
 };
 
 /**
- * Specifying this query as a `count` query.
+ * Thunk around countDocuments()
+ *
+ * @param {Function} [callback]
+ * @see countDocuments http://mongodb.github.io/node-mongodb-native/3.1/api/Collection.html#countDocuments
+ * @api private
+ */
+
+Query.prototype._countDocuments = function(callback) {
+  try {
+    this.cast(this.model);
+  } catch (err) {
+    this.error(err);
+  }
+
+  if (this.error()) {
+    return callback(this.error());
+  }
+
+  const conds = this._conditions;
+  const options = this._optionsForExec();
+
+  this._collection.collection.countDocuments(conds, options, utils.tick(callback));
+};
+
+/**
+ * Specifies this query as a `count` query. This method is deprecated, use
+ * `countDocuments()` instead.
  *
  * Passing a `callback` executes the query.
  *
@@ -1769,6 +1795,7 @@ Query.prototype._count = function(callback) {
  *       console.log('there are %d kittens', count);
  *     })
  *
+ * @deprecated
  * @param {Object} [criteria] mongodb selector
  * @param {Function} [callback] optional params are (error, count)
  * @return {Query} this
@@ -1798,6 +1825,58 @@ Query.prototype.count = function(conditions, callback) {
   return this;
 };
 
+/**
+ * Specifies this query as a `countDocuments()` query. Behaves like `count()`,
+ * except for [`$where` and a couple geospatial operators](http://mongodb.github.io/node-mongodb-native/3.1/api/Collection.html#countDocuments).
+ *
+ * Passing a `callback` executes the query.
+ *
+ * This function triggers the following middleware.
+ *
+ * - `countDocuments()`
+ *
+ * ####Example:
+ *
+ *     const countQuery = model.where({ 'color': 'black' }).countDocuments();
+ *
+ *     query.countDocuments({ color: 'black' }).count(callback);
+ *
+ *     query.countDocuments({ color: 'black' }, callback);
+ *
+ *     query.where('color', 'black').countDocuments(function(err, count) {
+ *       if (err) return handleError(err);
+ *       console.log('there are %d kittens', count);
+ *     });
+ *
+ * @param {Object} [criteria] mongodb selector
+ * @param {Function} [callback] optional params are (error, count)
+ * @return {Query} this
+ * @see countDocuments http://mongodb.github.io/node-mongodb-native/3.1/api/Collection.html#countDocuments
+ * @api public
+ */
+
+Query.prototype.countDocuments = function(conditions, callback) {
+  if (typeof conditions === 'function') {
+    callback = conditions;
+    conditions = undefined;
+  }
+
+  conditions = utils.toObject(conditions);
+
+  if (mquery.canMerge(conditions)) {
+    this.merge(conditions);
+  }
+
+  this.op = 'countDocuments';
+  if (!callback) {
+    return this;
+  }
+
+  this._countDocuments(callback);
+
+  return this;
+};
+
 /**
  * Declares or executes a distict() operation.
  *

test/model.test.js

@@ -3319,6 +3319,16 @@ describe('Model', function() {
       });
     });
 
+    it('countDocuments()', function() {
+      const BlogPost = db.model('BlogPost' + random(), bpSchema);
+
+      return BlogPost.create({ title: 'foo' }).
+        then(() => BlogPost.count({ title: 'foo' }).exec()).
+        then(count => {
+          assert.equal(count, 1);
+        });
+    });
+
     it('update()', function(done) {
       var col = 'BlogPost' + random();
       var BlogPost = db.model(col, bpSchema);

test/query.test.js

@@ -1129,7 +1129,7 @@ describe('Query', function() {
         assert.ifError(error);
         M.deleteOne({ name: /Stark/ }, function(error) {
           assert.ifError(error);
-          M.count({}, function(error, count) {
+          M.countDocuments({}, function(error, count) {
             assert.ifError(error);
             assert.equal(count, 1);
             done();
@@ -1250,7 +1250,7 @@ describe('Query', function() {
         Test.remove({ name: /Stark/ }).setOptions({ single: true }).exec(function(error, res) {
           assert.ifError(error);
           assert.equal(res.n, 1);
-          Test.count({}, function(error, count) {
+          Test.countDocuments({}, function(error, count) {
             assert.ifError(error);
             assert.equal(count, 1);
             done();
@@ -1671,6 +1671,12 @@ describe('Query', function() {
         });
       });
 
+      it('ignores sort when passed to countDocuments', function() {
+        var Product = db.model('Product', 'Product_setOptions_test');
+        return Product.create({}).
+          then(() => Product.find().sort({_id: 1}).countDocuments({}).exec());
+      });
+
       it('ignores count when passed to sort', function(done) {
         var Product = db.model('Product', 'Product_setOptions_test');
         Product.find().count({}).sort({_id: 1}).exec(function(error) {
@@ -2698,7 +2704,7 @@ describe('Query', function() {
         Object.assign(query, { price: priceQuery });
 
         yield Model.create(tests);
-        var count = yield Model.count(query);
+        var count = yield Model.countDocuments(query);
         assert.strictEqual(count, 9);
       });
     });