Implement ToString function

query_executors/memory_executor/memory_executor.go

@@ -188,6 +188,8 @@ func getFieldValue(field parsers.SelectItem, queryParameters map[string]interfac
 			return strings_Concat(typedValue.Arguments, queryParameters, row)
 		case parsers.FunctionCallIndexOf:
 			return strings_IndexOf(typedValue.Arguments, queryParameters, row)
+		case parsers.FunctionCallToString:
+			return strings_ToString(typedValue.Arguments, queryParameters, row)
 		case parsers.FunctionCallIsDefined:
 			return typeChecking_IsDefined(typedValue.Arguments, queryParameters, row)
 		}

query_executors/memory_executor/memory_executor_string_functions_test.go

@@ -9,8 +9,8 @@ import (
 
 func Test_Execute_StringFunctions(t *testing.T) {
 	mockData := []memoryexecutor.RowType{
-		map[string]interface{}{"id": "123", "pk": "aaa", "str": "hello"},
-		map[string]interface{}{"id": "456", "pk": "bbb", "str": "world"},
+		map[string]interface{}{"id": "123", "pk": "aaa", "str": "hello", "rng_type": true},
+		map[string]interface{}{"id": "456", "pk": "bbb", "str": "world", "rng_type": 159},
 		map[string]interface{}{"id": "789", "pk": "AAA", "str": "cool world"},
 	}
 
@@ -343,4 +343,38 @@ func Test_Execute_StringFunctions(t *testing.T) {
 			},
 		)
 	})
+
+	t.Run("Should execute function ToString()", func(t *testing.T) {
+		testQueryExecute(
+			t,
+			parsers.SelectStmt{
+				SelectItems: []parsers.SelectItem{
+					{
+						Path: []string{"c", "id"},
+						Type: parsers.SelectItemTypeField,
+					},
+					{
+						Alias: "str",
+						Type:  parsers.SelectItemTypeFunctionCall,
+						Value: parsers.FunctionCall{
+							Type: parsers.FunctionCallToString,
+							Arguments: []interface{}{
+								parsers.SelectItem{
+									Path: []string{"c", "rng_type"},
+									Type: parsers.SelectItemTypeField,
+								},
+							},
+						},
+					},
+				},
+				Table: parsers.Table{Value: "c"},
+			},
+			mockData,
+			[]memoryexecutor.RowType{
+				map[string]interface{}{"id": "123", "str": "true"},
+				map[string]interface{}{"id": "456", "str": "159"},
+				map[string]interface{}{"id": "789", "str": ""},
+			},
+		)
+	})
 }

query_executors/memory_executor/string_functions.go

@@ -96,6 +96,11 @@ func strings_IndexOf(arguments []interface{}, queryParameters map[string]interfa
 	}
 }
 
+func strings_ToString(arguments []interface{}, queryParameters map[string]interface{}, row RowType) string {
+	value := getFieldValue(arguments[0].(parsers.SelectItem), queryParameters, row)
+	return convertToString(value)
+}
+
 func getBoolFlag(arguments []interface{}, queryParameters map[string]interface{}, row RowType) bool {
 	ignoreCase := false
 	if len(arguments) > 2 && arguments[2] != nil {
@@ -127,6 +132,8 @@ func convertToString(value interface{}) string {
 		return fmt.Sprintf("%d", v)
 	case float32, float64:
 		return fmt.Sprintf("%f", v)
+	case bool:
+		return fmt.Sprintf("%t", v)
 	}
 	return ""
 }