Fix filtering for null fields

Author: Dragomir-Ivanov

rest/method_get_test.go

@@ -286,3 +286,60 @@ func TestGetListFieldHandler(t *testing.T) {
 		t.Run(n, tc.Test)
 	}
 }
+
+func TestGetListFilter(t *testing.T) {
+	sharedInit := func() *requestTestVars {
+		s := mem.NewHandler()
+		s.Insert(context.TODO(), []*resource.Item{
+			{ID: "1", Payload: map[string]interface{}{"id": 1, "foo": "bar"}},
+			{ID: "2", Payload: map[string]interface{}{"id": 2, "foo": nil}},
+			{ID: "3", Payload: map[string]interface{}{"id": 3, "foo2": "bar2"}},
+		})
+
+		idx := resource.NewIndex()
+		idx.Bind("foo", schema.Schema{
+			Fields: schema.Fields{
+				"foo": {
+					Filterable: true,
+					Validator:  &schema.AnyOf{&schema.Null{}, &schema.String{}},
+				},
+			},
+		}, s, resource.DefaultConf)
+
+		return &requestTestVars{
+			Index:   idx,
+			Storers: map[string]resource.Storer{"foo": s},
+		}
+	}
+
+	tests := map[string]requestTest{
+		`filter:string`: {
+			Init: sharedInit,
+			NewRequest: func() (*http.Request, error) {
+				return http.NewRequest("GET", `/foo?filter={foo:""}`, nil)
+			},
+			ResponseCode: 200,
+			ResponseBody: `[]`,
+		},
+		`filter:string2`: {
+			Init: sharedInit,
+			NewRequest: func() (*http.Request, error) {
+				return http.NewRequest("GET", `/foo?filter={foo:"bar"}`, nil)
+			},
+			ResponseCode: 200,
+			ResponseBody: `[{"foo":"bar","id":1}]`,
+		},
+		`filter:null`: {
+			Init: sharedInit,
+			NewRequest: func() (*http.Request, error) {
+				return http.NewRequest("GET", `/foo?filter={foo:null}`, nil)
+			},
+			ResponseCode: 200,
+			ResponseBody: `[{"foo":null,"id":2},{"foo2":"bar2","id":3}]`,
+		},
+	}
+	for n, tc := range tests {
+		tc := tc // capture range variable
+		t.Run(n, tc.Test)
+	}
+}

schema/query/predicate_parser.go

@@ -305,6 +305,8 @@ func (p *predicateParser) parseValue() (Value, error) {
 		return p.parseValues()
 	case 't', 'f':
 		return p.parseBool()
+	case 'n':
+		return p.parseNull()
 	default:
 		if (c >= '0' && c <= '9') || c == '-' {
 			// Parse a number
@@ -394,6 +396,16 @@ func (p *predicateParser) parseBool() (bool, error) {
 	return false, errors.New("not a boolean")
 }
 
+// parseNull parses a JSON Null value.
+func (p *predicateParser) parseNull() (Value, error) {
+	c := p.peek()
+	if c == 'n' && p.pos+4 <= len(p.query) && p.query[p.pos:p.pos+4] == "null" {
+		p.pos += 4
+		return nil, nil
+	}
+	return nil, errors.New("not null")
+}
+
 // parseNumber parses a number as float.
 func (p *predicateParser) parseNumber() (float64, error) {
 	end := p.pos

schema/query/predicate_parser_test.go

@@ -42,6 +42,11 @@ func TestParse(t *testing.T) {
 			Predicate{&Equal{Field: "foo", Value: false}},
 			nil,
 		},
+		{
+			`{"foo": null}`,
+			Predicate{&Equal{Field: "foo", Value: nil}},
+			nil,
+		},
 		{
 			`{"foo": "bar \n\" ❤️"}`,
 			Predicate{&Equal{Field: "foo", Value: "bar \n\" ❤️"}},
@@ -214,6 +219,11 @@ func TestParse(t *testing.T) {
 			Predicate{},
 			errors.New("char 8: foo: not a string: unexpected EOF"),
 		},
+		{
+			`{"foo": nul`,
+			Predicate{},
+			errors.New("char 8: foo: not null"),
+		},
 		{
 			`{"foo": {"$ne": {"bar", "baz"}}}`,
 			Predicate{},