[SWIFT4] Dates Are Inconsistently Encoded

Created by: james-rantmedia

Description

The generated code for GET requests that have URL Query Parameters that are dates currently encodes the date to JSON and inserts it as a query parameter.

The problem with this is that it is possible for the encoded date to contain a + character, which is a valid character in a query parameter, but not as an encoded space, as intended.

My problem example:

I have a date with a timezone component, like 2018-11-13T13:20:14.421+01:00. Adding this date to a URL's query results in: https://example.com?date=2018-11-13T13:20:14.421+01:00. The + is not encoded by URLQueryItem because it is a valid character.

However, when the server receives the request and decodes the query parameters, the result is 2018-11-13T13:20:14.421 01:00. The + was decoded to a space. This is unintentional, and the server responds with HTTP 400 Bad Request.

openapi-generator version

3.3.2

Steps to reproduce

• Generate code for Swift4 from an OpenAPI Spec that has a GET request with URL query parameters, one of which is a Date.
• Call the generated request method passing a date that has a positive timezone adjustment, eg 2018-11-13T13:20:14.421+01:00

Related issues/PRs

I will submit a PR to address this issue and update this issue.

Suggest a fix/enhancement

Modify the template for API classes to include a URL encoding step for dates added as query parameters. Eg:

{{#queryParams}}
{{> _param}}{{#isDateTime}}.addingPercentEncoding(withAllowedCharacters: CharacterSet(charactersIn: "1234567890T.-")){{/isDateTime}}{{#hasMore}}, {{/hasMore}}
{{/queryParams}}