json2: encode array of all and verify sum type (#17051)

vlib/x/json2/encoder.v

@@ -390,6 +390,12 @@ fn (e &Encoder) encode_array[U](val []U, level int, mut wr io.Writer) ! {
 			// e.encode_array(val[i], level + 1, mut wr)!
 		} $else $if U is $Struct {
 			e.encode_struct(val[i], level + 1, mut wr)!
+		} $else $if U is $Sumtype {
+			$if U is Any {
+				e.encode_any(val[i], level + 1, mut wr)!
+			} $else {
+				// TODO
+			}
 		} $else $if U is $Enum {
 			e.encode_any(i64(val[i]), level + 1, mut wr)!
 		} $else {

vlib/x/json2/encoder_test.v

@@ -1,6 +1,11 @@
 import x.json2 as json
 import strings
 
+struct StructType[T] {
+mut:
+	val T
+}
+
 fn test_json_string_characters() {
 	text := json.raw_decode(r'"\n\r\b\f\t\\\"\/"') or { '' }
 	assert text.json_str() == '"\\n\\r\\b\\f\\t\\\\\\"\\/"'
@@ -116,7 +121,15 @@ fn test_encode_encodable() {
 }
 
 fn test_encode_array() {
-	assert json.encode([1, 2, 3]) == '[1,2,3]'
+	array_of_struct := [StructType[[]bool]{
+		val: [false, true]
+	}, StructType[[]bool]{
+		val: [true, false]
+	}]
+
+	assert json.encode_array([1, 2, 3]) == '[1,2,3]'
+
+	assert json.encode_array(array_of_struct) == '[{"val":[false,true]},{"val":[true,false]}]'
 }
 
 fn test_encode_simple() {

vlib/x/json2/json2.v

@@ -79,25 +79,36 @@ pub fn decode[T](src string) !T {
 
 // encode is a generic function that encodes a type into a JSON string.
 pub fn encode[T](val T) string {
+	$if T is $Array {
+		$compile_error('Cannot use `json.encode` to encode array. Try `json.encode_array` instead')
+	}
 	mut sb := strings.new_builder(64)
+
 	defer {
 		unsafe { sb.free() }
 	}
-	$if T is $Array {
+
-		mut array_of_any := []Any{}
-		for value in val {
-			array_of_any << value
-		}
-		default_encoder.encode_value(array_of_any, mut sb) or {
-			dump(err)
-			default_encoder.encode_value[Null](null, mut sb) or {}
-		}
-	} $else {
 	default_encoder.encode_value(val, mut sb) or {
 		dump(err)
 		default_encoder.encode_value[Null](null, mut sb) or {}
 	}
+
+	return sb.str()
+}
+
+// encode_array is a generic function that encodes a array into a JSON string.
+pub fn encode_array[T](val []T) string {
+	mut sb := strings.new_builder(64)
+
+	defer {
+		unsafe { sb.free() }
 	}
+
+	default_encoder.encode_array(val, 1, mut sb) or {
+		dump(err)
+		default_encoder.encode_value[Null](null, mut sb) or {}
+	}
+
 	return sb.str()
 }