Initial commit

node_modules/mongodb/lib/operations/count_documents.js

@@ -0,0 +1,41 @@
+'use strict';
+
+const AggregateOperation = require('./aggregate');
+
+class CountDocumentsOperation extends AggregateOperation {
+  constructor(collection, query, options) {
+    const pipeline = [{ $match: query }];
+    if (typeof options.skip === 'number') {
+      pipeline.push({ $skip: options.skip });
+    }
+
+    if (typeof options.limit === 'number') {
+      pipeline.push({ $limit: options.limit });
+    }
+
+    pipeline.push({ $group: { _id: 1, n: { $sum: 1 } } });
+
+    super(collection, pipeline, options);
+  }
+
+  execute(server, callback) {
+    super.execute(server, (err, result) => {
+      if (err) {
+        callback(err, null);
+        return;
+      }
+
+      // NOTE: We're avoiding creating a cursor here to reduce the callstack.
+      const response = result.result;
+      if (response.cursor == null || response.cursor.firstBatch == null) {
+        callback(null, 0);
+        return;
+      }
+
+      const docs = response.cursor.firstBatch;
+      callback(null, docs.length ? docs[0].n : 0);
+    });
+  }
+}
+
+module.exports = CountDocumentsOperation;