Implement the responseFields query parameter (#158)

[ci skip]

Author: Clément Le Provost

Source/Query.swift

@@ -708,6 +708,28 @@ open class Query : AbstractQuery {
             }
         }
     }
+    
+    // MARK: Advanced
+    
+    /// Choose which fields the response will contain. Applies to search and browse queries.
+    ///
+    /// By default, all fields are returned. If this parameter is specified, only the fields explicitly listed will be
+    /// returned, unless `*` is used, in which case all fields are returned. Specifying an empty list or unknown field
+    /// names is an error.
+    ///
+    /// This parameter is mainly intended to limit the response size. For example, for complex queries, echoing of
+    /// request parameters in the response's params field can be undesirable.
+    ///
+    /// Some fields cannot be filtered out:
+    ///
+    /// - `warning` message
+    /// - `cursor` in browse queries
+    /// - fields triggered explicitly via `getRankingInfo`
+    ///
+    @objc public var responseFields: [String]? {
+        get { return Query.parseStringArray(self["responseFields"]) }
+        set { self["responseFields"] = Query.buildJSONArray(newValue) }
+    }
 
     // MARK: - Initialization
 

Tests/ObjectiveCBridging.m

@@ -118,6 +118,7 @@ - (void)testQuery {
     query.minimumAroundRadius = [NSNumber numberWithInt:666];
     query.insideBoundingBox = @[ [[GeoRect alloc] initWithP1:[[LatLng alloc] initWithLat:123.45 lng:67.89] p2:[[LatLng alloc] initWithLat:129.99 lng:69.99]] ];
     query.insidePolygon = @[ [[LatLng alloc] initWithLat:123.45 lng:67.89], [[LatLng alloc] initWithLat:129.99 lng:69.99], [[LatLng alloc] initWithLat:0.0 lng:0.0] ];
+    query.responseFields = @[ @"foo", @"bar" ];
 }
 
 - (void)testClient {

Tests/QueryTests.swift

@@ -673,4 +673,14 @@ class QueryTests: XCTestCase {
         XCTAssertNotNil(query1.alternativesAsExact)
         XCTAssertEqual(0, query1.alternativesAsExact?.count)
     }
+    
+    func test_responseFields() {
+        let query1 = Query()
+        XCTAssertNil(query1.responseFields)
+        query1.responseFields = ["foo", "bar"]
+        XCTAssertEqual(query1.responseFields!, ["foo", "bar"])
+        XCTAssertEqual(query1["responseFields"], "[\"foo\",\"bar\"]")
+        let query2 = Query.parse(query1.build())
+        XCTAssertEqual(query2.responseFields!, ["foo", "bar"])
+    }
 }