[Feature] Ability to handle multiple values for a singular key in .fetch() with APIRequestContext

[szuszik]

I'm working on a project that requires sending POST requests with 'application/x-www-form-urlencoded' encoding, specifically handling multiple values for a singular key (e.g., 'scope'). This is a common pattern in OAuth2 authorization and other API interactions, where you need to, for example, define authorization grant types.

Currently, I can achieve this with Fetch in JavaScript, but I'm unable to find a way to replicate this behavior using Playwright's APIRequestContext class.

let requestHeaders = new Headers();
requestHeaders.append("Content-Type", "application/x-www-form-urlencoded");

let urlEncoded = new URLSearchParams();
urlEncoded.append("scope", "value1");
urlEncoded.append("scope", "value2");
urlencoded.append("scope", "value3");
urlencoded.append("scope", "value4");
// and so on

let requestOptions = {
  method: 'POST',
  headers: requestHeaders,
  body: urlEncoded,
  redirect: 'no-follow'
};

fetch("https://example.com/authorize", requestOptions)
  .then(response => response.text())
  .then(result => console.log(result))
  .catch(error => console.log('error', error));

However, I'm struggling to find a way to replicate this behavior using the APIRequestContext class in Playwright. Here's what I've tried so far:

await apiRequestContext.post('https://example.com/authorize', {
  headers: { "Content-Type": "application/x-www-form-urlencoded" },
  form: {
    "response_type": "auth_code",
    "scope": "value1", // How to handle multiple values for 'scope'?
    // rest of the parameters
  }
});

Since currently there's no way to handle multiple values for a singular key like 'key' using the APIRequestContext, I think it would be beneficial to be able to provide multiple values for one key, in a similar fashion it is achieved by URLSearchParams. It could be, for example, passed in an array of strings.