fix: sanitizes extra dollar signs for operators

README.md

@@ -98,7 +98,7 @@ If you run a MongoDB with authentification ([Docker's example here](https://gith
       <td>allowExtendedOperators</td>
       <td>Boolean</td>
       <td><code>false</code></td>
-      <td>Set to <code>true</code> to enable using MongoDB operators such as <code>$currentDate, $inc, $max, $min, $mul, $rename, $setOnInsert, $set, $unset, $addToSet, $pop, $pullAll, $pull, $pushAll, $push</code>, and <code>$bit</code>.</td>
+      <td>Set to <code>true</code> to enable using MongoDB operators such as <code>$currentDate, $inc, $max, $min, $mul, $rename, $setOnInsert, $set, $unset, $addToSet, $pop, $pullAll, $pull, $push</code>, and <code>$bit</code>. See <a href="https://loopback.io/doc/en/lb4/MongoDB-connector.html#update-operators" class="external-link" rel="nofollow">Update Operators</a> section below</td>
     </tr>
     <tr>
       <td>enableGeoIndexing</td>
@@ -249,6 +249,32 @@ The .loopbackrc file is in JSON format, for example:
 
 </details>
 
+## Update Operators
+
+Except the comparison and logical operators LoopBack supports in the [operator list](https://loopback.io/doc/en/lb4/Where-filter.html#operators) of `Where` filter, you can also enable [MongoDB update operators](https://docs.mongodb.com/manual/reference/operator/update/) for `update*` methods by setting the flag `allowExtendedOperators` to `true` in the datasource configuration.
+
+Here is an example of updating the price for all the products under category `furniture` if their current price is lower than 100:
+
+```
+await productRepo.updateAll({ $max: { price: 100 }}, { category: {eq: 'furniture'} // where clause goes in here });
+```
+
+<details><summary markdown="span"><strong>For LoopBack 3 users</strong></summary>
+
+```
+Product.updateAll(
+            { category: {eq: 'furniture'} // where clause goes in here },
+            {$max: {price: 100}},
+            options,
+            function(err, updateproducts) {
+           ...
+```
+
+</details>
+
+{% include tip.html content="you **will not** need the dollar sign `'$'` for operators in the Where
+clause." %}
+
 ## Handling ObjectId
 
 MongoDB uses `ObjectId` for its primary key, which is an object instead of a

lib/mongodb.js

@@ -765,7 +765,6 @@ MongoDB.prototype.parseUpdateData = function(modelName, data, options) {
       '$pop',
       '$pullAll',
       '$pull',
-      '$pushAll',
       '$push',
       // Bitwise operator
       '$bit',
@@ -993,6 +992,7 @@ MongoDB.prototype.buildWhere = function(modelName, where, options) {
     const modelCtor = self._models[modelName];
 
     if (spec) {
+      spec = trimLeadingDollarSigns(spec);
       if (spec === 'between') {
         query[k] = {$gte: cond[0], $lte: cond[1]};
       } else if (spec === 'inq') {
@@ -1994,6 +1994,17 @@ function isObjectIDProperty(modelCtor, propDef, value, options) {
   }
 }
 
+/**
+ * Removes extra dollar sign '$' for operators
+ *
+ * @param {*} spec the operator for Where filter
+ */
+function trimLeadingDollarSigns(spec) {
+  return spec.replace(/^(\$)+/, '');
+}
+
+exports.trimLeadingDollarSigns = trimLeadingDollarSigns;
+
 function sanitizeFilter(filter, options) {
   options = Object.assign({}, options);
   if (options && options.disableSanitization) return filter;

test/mongodb.test.js

@@ -12,6 +12,7 @@ const testUtils = require('../lib/test-utils');
 const async = require('async');
 const sinon = require('sinon');
 const sanitizeFilter = require('../lib/mongodb').sanitizeFilter;
+const trimLeadingDollarSigns = require('../lib/mongodb').trimLeadingDollarSigns;
 
 const GeoPoint = require('loopback-datasource-juggler').GeoPoint;
 
@@ -1485,7 +1486,7 @@ describe('mongodb connector', function() {
                 should.not.exist(err);
                 updatedusers.should.have.property('count', 1);
 
-                User.find({where: {name: 'Simon'}}, function(
+                User.find({where: {name: {$eq: 'Simon'}}}, function(
                   err,
                   foundusers,
                 ) {
@@ -3726,6 +3727,29 @@ describe('mongodb connector', function() {
     });
   });
 
+  context('trimLeadingDollarSigns', () =>{
+    it('removes an extra leading dollar sign in ths operators', () => {
+      const spec = '$eq';
+      const updatedSpec = trimLeadingDollarSigns(spec);
+      updatedSpec.should.equal('eq');
+    });
+    it('removes extra leading dollar signs in ths operators', () => {
+      const spec = '$$eq';
+      const updatedSpec = trimLeadingDollarSigns(spec);
+      updatedSpec.should.equal('eq');
+    });
+
+    it('remains the same if the input does not contain any dollar signs', () => {
+      const spec = 'eq';
+      const updatedSpec = trimLeadingDollarSigns(spec);
+      updatedSpec.should.equal(spec);
+    });
+    it('remains the same if the input does not start with dollar signs', () => {
+      const spec = 'eq$';
+      const updatedSpec = trimLeadingDollarSigns(spec);
+      updatedSpec.should.equal(spec);
+    });
+  });
   context('sanitizeFilter()', () => {
     it('returns filter if not an object', () => {
       const input = false;