[JAVA][Client][RestTemplate] Query parameters not properly URL-encoded

Created by: rubms

Description

Before https://github.com/OpenAPITools/openapi-generator/pull/260 (fix for https://github.com/OpenAPITools/openapi-generator/issues/249), query parameters were not URL encoded.

https://github.com/OpenAPITools/openapi-generator/pull/260 attempts to fix this problem, but after https://github.com/OpenAPITools/openapi-generator/pull/260 was applied a problem still persists: URLs are not correctly URL-encoded. The % characters of the encoded URL get re-encoded. For instance: the query parameter date=2018-07-25T00:00:00+02:00, which should be URL-encoded as date=2018-07-25T00%3A00%3A00%2B02%3A00 is actually encoded as date=2018-07-25T00%253A00%253A00%252B02%253A00.

This way, the server interprets the query parameter as 2018-07-25T00%3A00%3A00%2B02%3A00 instead of 2018-07-25T00:00:00+02:00.

openapi-generator version

3.1.2-SNAPSHOT (build 20180724.111212-30)

OpenAPI declaration file content or url

  /pets:
    get:
      summary: List all pets
      operationId: listPets
      tags:
        - pets
      parameters:
        - name: soldAfter
          in: query
          description: If specified, only pets sold after the given date and time will be returned.
          required: false
          schema:
            type: string
            format: date-time

Command line used for generation

java -jar openapi-generator-cli-3.1.2-20180724.111212-30.jar generate -g java -i .\sample.yml -c .\config.json -o test_output

config.json:

{
	"library": "resttemplate",
	"dateLibrary": "java8"
}

Steps to reproduce

Auto-generate the code from the swagger specification. Perform an HTTP GET request from the auto-generated code including a date-time as query parameter. The URL of the HTTP request will be incorrectly URL-encoded, having a double encoding of the % characters.

Related issues/PRs

The https://github.com/OpenAPITools/openapi-generator/issues/249 issue originally addresses the problem in the URL-encoding of query parameters in the Java RestTemplate client generation. A fix is attempted in https://github.com/OpenAPITools/openapi-generator/pull/260, but without full success, in which this re-encoding of % characters is experienced.

Suggest a fix/enhancement

The problem lies in the invokeAPI of the auto-generated ApiClient class:

        final UriComponentsBuilder builder = UriComponentsBuilder.fromHttpUrl(basePath).path(path);
        if (queryParams != null) {
            //encode the query parameters in case they contain unsafe characters
            for (List<String> values : queryParams.values()) {
                if (values != null) {
                    for (int i = 0; i < values.size(); i++) {
                        try {
                            values.set(i, URLEncoder.encode(values.get(i), "utf8"));
                        } catch (UnsupportedEncodingException e) {

                        }
                    }
                }
            }
            builder.queryParams(queryParams);
        }
        
        final BodyBuilder requestBuilder = RequestEntity.method(method, builder.build().toUri());

The query parameters are explicitly encoded in the for loop, but the builder.build().toUri() piece of code is escaping the % characters in the URL!

Building the URL like this would fix the problem:

        final UriComponentsBuilder builder = UriComponentsBuilder.fromHttpUrl(basePath).path(path);
        if (queryParams != null) {
            //encode the query parameters in case they contain unsafe characters
            for (List<String> values : queryParams.values()) {
                if (values != null) {
                    for (int i = 0; i < values.size(); i++) {
                        try {
                            values.set(i, URLEncoder.encode(values.get(i), "utf8"));
                        } catch (UnsupportedEncodingException e) {

                        }
                    }
                }
            }
            builder.queryParams(queryParams);
        }

        URI uri;
        try {
            uri = new URI(builder.build().toUriString());
        } catch(URISyntaxException ex)  {
            throw new RestClientException("Could not build URL: " + builder.toUriString(), ex);
        }

        final BodyBuilder requestBuilder = RequestEntity.method(method, uri);