fix: force to decode as utf-8 when header contains application/json t…

…o avoid text garbling. (OpenAPITools#1700)

* fix: force to decode as utf-8 when header contains application/json to avoid text garbling.

The original processing is using `response.body` to deserialize as json.
However, this is decoded by latin1 if the header contains only "application/json" instead of "application/json; charset=utf-8".

Because of this behavior, if the response body is encoded UTF-8 but the headers doesn't contain charset, the body will garbling.

cf: dart-lang/http#175

Since playframework 2.6 returns "Content-Type: application/json" without "charset=utf-8", I changed this parsing algolithm.

* fix: force to decode as utf-8 when header contains application/json to avoid text garbling on error.

modules/openapi-generator/src/main/resources/dart/api.mustache

@@ -89,22 +89,22 @@ class {{classname}} {
                                              authNames);
 
     if(response.statusCode >= 400) {
-      throw new ApiException(response.statusCode, response.body);
+      throw new ApiException(response.statusCode, _decodeBodyBytes(response));
     } else if(response.body != null) {
       {{#isListContainer}}
         {{#returnType}}
-      return (apiClient.deserialize(response.body, '{{{returnType}}}') as List).map((item) => item as {{returnBaseType}}).toList();
+      return (apiClient.deserialize(_decodeBodyBytes(response), '{{{returnType}}}') as List).map((item) => item as {{returnBaseType}}).toList();
         {{/returnType}}
       {{/isListContainer}}
       {{^isListContainer}}
         {{#isMapContainer}}
           {{#returnType}}
-      return new {{{returnType}}}.from(apiClient.deserialize(response.body, '{{{returnType}}}'));
+      return new {{{returnType}}}.from(apiClient.deserialize(_decodeBodyBytes(response), '{{{returnType}}}'));
           {{/returnType}};
         {{/isMapContainer}}
         {{^isMapContainer}}
           {{#returnType}}
-      return apiClient.deserialize(response.body, '{{{returnType}}}') as {{{returnType}}};
+      return apiClient.deserialize(_decodeBodyBytes(response), '{{{returnType}}}') as {{{returnType}}};
           {{/returnType}}
         {{/isMapContainer}}
       {{/isListContainer}}

modules/openapi-generator/src/main/resources/dart/api_helper.mustache

@@ -50,3 +50,15 @@ String parameterToString(dynamic value) {
     return value.toString();
   }
 }
+
+/// Returns the decoded body by utf-8 if application/json with the given headers.
+/// Else, returns the decoded body by default algorithm of dart:http.
+/// Because avoid to text garbling when header only contains "application/json" without "; charset=utf-8".
+String _decodeBodyBytes(Response response) {
+  var contentType = response.headers['content-type'];
+  if (contentType != null && contentType.contains("application/json")) {
+    return utf8.decode(response.bodyBytes);
+  } else {
+    return response.body;
+  }
+}

modules/openapi-generator/src/main/resources/dart2/api.mustache

@@ -89,22 +89,22 @@ class {{classname}} {
                                              authNames);
 
     if(response.statusCode >= 400) {
-      throw new ApiException(response.statusCode, response.body);
+      throw new ApiException(response.statusCode, _decodeBodyBytes(response));
     } else if(response.body != null) {
       {{#isListContainer}}
         {{#returnType}}
-      return (apiClient.deserialize(response.body, '{{{returnType}}}') as List).map((item) => item as {{returnBaseType}}).toList();
+      return (apiClient.deserialize(_decodeBodyBytes(response), '{{{returnType}}}') as List).map((item) => item as {{returnBaseType}}).toList();
         {{/returnType}}
       {{/isListContainer}}
       {{^isListContainer}}
         {{#isMapContainer}}
           {{#returnType}}
-      return new {{{returnType}}}.from(apiClient.deserialize(response.body, '{{{returnType}}}'));
+      return new {{{returnType}}}.from(apiClient.deserialize(_decodeBodyBytes(response), '{{{returnType}}}'));
           {{/returnType}};
         {{/isMapContainer}}
         {{^isMapContainer}}
           {{#returnType}}
-      return apiClient.deserialize(response.body, '{{{returnType}}}') as {{{returnType}}};
+      return apiClient.deserialize(_decodeBodyBytes(response), '{{{returnType}}}') as {{{returnType}}};
           {{/returnType}}
         {{/isMapContainer}}
       {{/isListContainer}}

modules/openapi-generator/src/main/resources/dart2/api_helper.mustache

@@ -50,3 +50,15 @@ String parameterToString(dynamic value) {
     return value.toString();
   }
 }
+
+/// Returns the decoded body by utf-8 if application/json with the given headers.
+/// Else, returns the decoded body by default algorithm of dart:http.
+/// Because avoid to text garbling when header only contains "application/json" without "; charset=utf-8".
+String _decodeBodyBytes(Response response) {
+  var contentType = response.headers['content-type'];
+  if (contentType != null && contentType.contains("application/json")) {
+    return utf8.decode(response.bodyBytes);
+  } else {
+    return response.body;
+  }
+}