feat(query) add $sqs simple_query_string query

README.md

@@ -226,6 +226,26 @@ query: {
 }
 ```
 
+### $sqs
+[simple_query_string](https://www.elastic.co/guide/en/elasticsearch/reference/current/query-dsl-simple-query-string-query.html). A query that uses the SimpleQueryParser to parse its context. Optional `$default_operator` which is set to `or` by default but can be set to `and` if required.
+
+```js
+query: {
+  $sqs: {
+    $fields: [
+      'title^5',
+      'description'
+    ],
+    $query: '+like +javascript',
+    $default_operator: 'and'
+  }
+}
+```
+This can also be expressed in an URL as the following:
+```http
+http://localhost:3030/users?$sqs[$fields][]=title^5&$sqs[$fields][]=description&$sqs[$query]=+like +javascript&$sqs[$default_operator]=and
+```
+
 ## Parent-child relationship
 Elasticsearch supports [parent-child relationship](https://www.elastic.co/guide/en/elasticsearch/reference/current/mapping-parent-field.html), however it is not exactly the same as in relational databases. feathers-elasticsearch supports all CRUD operations for Elasticsearch types with parent mapping, and does that with the Elasticsearch constrains. Therefore:
 

src/utils/parse-query.js

@@ -20,6 +20,7 @@ const specialQueryHandlers = {
   $or: $or,
   $and: $and,
   $all: $all,
+  $sqs: $sqs,
   $child: (...args) => $childOr$parent('$child', ...args),
   $parent: (...args) => $childOr$parent('$parent', ...args)
 };
@@ -66,6 +67,31 @@ function $and (value, esQuery, idProp) {
   return esQuery;
 }
 
+function $sqs (value, esQuery, idProp) {
+  if (value === null || value === undefined) {
+    return esQuery;
+  }
+
+  validateType(value, '$sqs', 'object');
+  validateType(value.$fields, `value.$fields`, 'array');
+  validateType(value.$query, `value.$query`, 'string');
+
+  if (value.$default_operator) {
+    validateType(value.$default_operator, `value.$default_operator`, 'string');
+  }
+
+  esQuery.must = esQuery.must || [];
+  esQuery.must.push({
+    simple_query_string: {
+      fields: value.$fields,
+      query: value.$query,
+      default_operator: value.$default_operator || 'or'
+    }
+  });
+
+  return esQuery;
+}
+
 function $childOr$parent (key, value, esQuery) {
   let subQuery;
   let queryName = key === '$child' ? 'has_child' : 'has_parent';

test/index.test.js

@@ -260,6 +260,27 @@ describe('Elasticsearch Service', () => {
             });
         });
 
+        it('can $sqs (simple_query_string)', () => {
+          return app.service(serviceName)
+            .find({
+              query: {
+                $sort: { name: 1 },
+                $sqs: {
+                  $fields: [
+                    'bio',
+                    'name^5'
+                  ],
+                  $query: '+like -javascript',
+                  $default_operator: 'and'
+                }
+              }
+            })
+            .then(results => {
+              expect(results.length).to.equal(1);
+              expect(results[0].name).to.equal('Moody');
+            });
+        });
+
         it('can $child', () => {
           return app.service(serviceName)
             .find({

test/utils/parse-query.js

@@ -41,6 +41,13 @@ export default function parseQueryTests () {
       expect(() => parseQuery({ $and: {} }, '_id')).to.throw(errors.BadRequest);
     });
 
+    it('should throw BadRequest if $sqs is not an object', () => {
+      expect(() => parseQuery({ $sqs: 12 }, '_id')).to.throw(errors.BadRequest);
+      expect(() => parseQuery({ $sqs: true }, '_id')).to.throw(errors.BadRequest);
+      expect(() => parseQuery({ $sqs: 'abc' }, '_id')).to.throw(errors.BadRequest);
+      expect(() => parseQuery({ $sqs: {} }, '_id')).to.throw(errors.BadRequest);
+    });
+
     it('should throw BadRequest if $child is not an object, null or undefined', () => {
       expect(() => parseQuery({ $child: 12 })).to.throw(errors.BadRequest);
       expect(() => parseQuery({ $child: true })).to.throw(errors.BadRequest);
@@ -257,6 +264,35 @@ export default function parseQueryTests () {
         .deep.equal(expectedResult);
     });
 
+    it('should return "must" $sqs', () => {
+      let query = {
+        $sqs: {
+          $fields: [
+            'description',
+            'title^5'
+          ],
+          $query: '-(track another)'
+        }
+      };
+      let expectedResult = {
+        must: [
+          {
+            simple_query_string: {
+              fields: [
+                'description',
+                'title^5'
+              ],
+              query: '-(track another)',
+              default_operator: 'or'
+            }
+          }
+        ]
+      };
+
+      expect(parseQuery(query, '_id')).to
+        .deep.equal(expectedResult);
+    });
+
     it('should return "prefix" query for $prefix', () => {
       let query = {
         user: { $prefix: 'ada' }