Реализована функция exists

pkg/expr/expr_test.go

@@ -39,6 +39,7 @@ func TestIsExpression(t *testing.T) {
 		{"time", fmt.Sprintf("d > Time.Time('%s')", now.Format(time.RFC3339)), true},
 		{"in", "In(s, [1,2,3])", true},
 		{"in", "In(s, 1)", true},
+		{"exists", "exists(s)", true},
 		{"text search or id", "id", false},
 		{"numbers", "3", false},
 	}

pkg/expr/mongo.go

@@ -404,6 +404,15 @@ func (c *compiler) CallNode(node *ast.CallNode) interface{} {
 		}
 
 		return bson.M{fields: bson.M{"$in": array}}
+	case "exists":
+		field := c.identifier(node.Arguments[0])
+		if field == "" {
+			panic("incorrect argument, empty field name")
+		}
+		return bson.M{"$or": bson.A{
+			bson.M{field: bson.M{"$exists": true, "$type": "array"}},
+			bson.M{field: bson.M{"$ne": nil}},
+		}}
 
 	case "icontains":
 		v := c.identifier(node.Arguments[0])

pkg/expr/mongo_test.go

@@ -30,6 +30,7 @@ func TestConvertToMongo(t *testing.T) {
 		{"equal", "s == 3", nil, bson.M{"s": 3}, false},
 		{"in array", "s in [1,2,3]", nil, bson.M{"s": bson.M{"$in": []interface{}{1, 2, 3}}}, false},
 		{"not in array", "s not in [1,2,3]", nil, bson.M{"s": bson.M{"$nin": []interface{}{1, 2, 3}}}, false},
+		{"exists", "exists(s)", nil, bson.M{"$or": bson.A{bson.M{"s": bson.M{"$exists": true, "$type": "array"}}, bson.M{"s": bson.M{"$ne": nil}}}}, false},
 		{"field#1", "s.test > 3", nil, bson.M{"s.test": bson.M{"$gt": 3}}, false},
 		{"field#2", "s['test'] > 3", nil, bson.M{"s.test": bson.M{"$gt": 3}}, false},
 		{"field#3", "s[test] > 3", nil, bson.M{"s.test": bson.M{"$gt": 3}}, false},