json2: add support for encoding embedded structs (fix #24994) (#25475)

Author: Larsimusrex

vlib/x/json2/encode.v

@@ -389,86 +389,110 @@ fn (mut encoder Encoder) cached_field_infos[T]() []EncoderFieldInfo {
 @[unsafe]
 fn (mut encoder Encoder) encode_struct[T](val T) {
 	encoder.output << `{`
+
+	is_first := encoder.encode_struct_fields(val, true, [], '')
+
+	if encoder.prettify && !is_first {
+		encoder.decrement_level()
+		encoder.add_indent()
+	}
+
+	encoder.output << `}`
+}
+
+@[unsafe]
+fn (mut encoder Encoder) encode_struct_fields[T](val T, was_first bool, old_used_keys []string, prefix string) bool {
 	field_infos := encoder.cached_field_infos[T]()
 	mut i := 0
-	mut is_first := true
+	mut is_first := was_first
+	mut used_keys := old_used_keys
+
 	$for field in T.fields {
-		field_info := field_infos[i]
-		i++
+		$if !field.is_embed {
+			field_info := field_infos[i]
 
-		mut write_field := true
+			mut write_field := true
 
-		if field_info.is_skip {
-			write_field = false
-		} else {
-			value := val.$(field.name)
+			if field_info.is_skip {
+				write_field = false
+			} else {
+				value := val.$(field.name)
 
-			if field_info.is_omitempty {
-				$if value is $option {
-					write_field = check_not_empty(value) or { false }
-				} $else {
-					write_field = check_not_empty(value) or { false }
+				if field_info.is_omitempty {
+					$if value is $option {
+						write_field = check_not_empty(value) or { false }
+					} $else {
+						write_field = check_not_empty(value) or { false }
+					}
 				}
-			}
 
-			if !field_info.is_required {
-				$if value is $option {
-					if value == none {
-						write_field = false
+				if !field_info.is_required {
+					$if value is $option {
+						if value == none {
+							write_field = false
+						}
 					}
 				}
 			}
-		}
 
-		$if field.indirections != 0 {
-			if val.$(field.name) == unsafe { nil } {
-				write_field = false
+			$if field.indirections != 0 {
+				if val.$(field.name) == unsafe { nil } {
+					write_field = false
+				}
 			}
-		}
 
-		if write_field {
-			if is_first {
+			if write_field {
+				if is_first {
+					if encoder.prettify {
+						encoder.increment_level()
+					}
+					is_first = false
+				} else {
+					encoder.output << `,`
+				}
 				if encoder.prettify {
-					encoder.increment_level()
+					encoder.add_indent()
 				}
-				is_first = false
-			} else {
-				encoder.output << `,`
-			}
-			if encoder.prettify {
-				encoder.add_indent()
-			}
 
-			encoder.encode_string(field_info.key_name)
+				if field_info.key_name in old_used_keys {
+					encoder.encode_string(prefix + field_info.key_name)
+				} else {
+					encoder.encode_string(field_info.key_name)
+					used_keys << field_info.key_name
+				}
 
-			encoder.output << `:`
-			if encoder.prettify {
-				encoder.output << ` `
-			}
+				encoder.output << `:`
+				if encoder.prettify {
+					encoder.output << ` `
+				}
 
-			$if field is $option {
-				if val.$(field.name) == none {
-					unsafe { encoder.output.push_many(null_string.str, null_string.len) }
-				} else {
+				$if field is $option {
+					if val.$(field.name) == none {
+						unsafe { encoder.output.push_many(null_string.str, null_string.len) }
+					} else {
+						encoder.encode_value(val.$(field.name))
+					}
+				} $else $if field.indirections == 1 {
+					encoder.encode_value(*val.$(field.name))
+				} $else $if field.indirections == 2 {
+					encoder.encode_value(**val.$(field.name))
+				} $else $if field.indirections == 3 {
+					encoder.encode_value(***val.$(field.name))
+				} $else {
 					encoder.encode_value(val.$(field.name))
 				}
-			} $else $if field.indirections == 1 {
-				encoder.encode_value(*val.$(field.name))
-			} $else $if field.indirections == 2 {
-				encoder.encode_value(**val.$(field.name))
-			} $else $if field.indirections == 3 {
-				encoder.encode_value(***val.$(field.name))
-			} $else {
-				encoder.encode_value(val.$(field.name))
 			}
 		}
+		i++
 	}
-	if encoder.prettify && !is_first {
-		encoder.decrement_level()
-		encoder.add_indent()
+	$for field in T.fields {
+		$if field.is_embed {
+			new_prefix := prefix + field.name + '.'
+			is_first = encoder.encode_struct_fields(val.$(field.name), is_first, used_keys,
+				new_prefix)
+		}
 	}
-
-	encoder.output << `}`
+	return is_first
 }
 
 fn (mut encoder Encoder) encode_custom[T](val T) {

vlib/x/json2/tests/encode_embedded_structs_test.v

@@ -0,0 +1,28 @@
+import x.json2 as json
+
+struct Baz {
+	c bool = true
+}
+
+struct Foo {
+	Baz
+	a int = 1
+	b int = 2
+}
+
+struct Bar {
+	Foo
+	a string = '1'
+	c string = '3'
+}
+
+fn test_embed() {
+	assert json.encode(Bar{}) == '{"a":"1","c":"3","Foo.a":1,"b":2,"Foo.Baz.c":true}'
+	assert json.encode(Bar{}, prettify: true) == '{
+    "a": "1",
+    "c": "3",
+    "Foo.a": 1,
+    "b": 2,
+    "Foo.Baz.c": true
+}'
+}