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kotlinlang

Does ktor come with a mechanism for properly building `application/x-www-form-urlencoded` strings from a map?

Is this for connecting to other services or some other purpose?

I’m trying to output a OAuth 2.0 Authorization Error Response. Something along the lines of ```
call.respond(401, mapOf(
    "error" to "invalid_request",
    "error_description" to "client_id is missing"
).toFormUrlEncoded())```

Hmm, aren’t you using oauth authentication feature?

I’m using Ktor to make an OAuth server. The documentation on the OAuth authentication feature suggests that it is for OAuth clients?

Will you contribute it back as a feature? :smile:

I’ll see what I can figure out haha. This is my first ever ktor app besides “hello world”, so I’m still getting my hands wet as it is haha

That’s fine! Having an OAuth server is a nice demo for a technology. I’m not yet sure how it fits into ktor features, but overall I think it’s a great thing to have

You can use <https://ktor.io/advanced/utilities.html#url-encoded>
But it works with a `List&lt;Pair&lt;String, String&gt;&gt;`, so you have first to convert the map into a list of pairs. Something like:

```
call.respond(401, mapOf(
    "error" to "invalid_request",
    "error_description" to "client_id is missing"
).toList().formUrlEncode())
```

or:

```
Parameters.build {
	append("error", "invalid_request")
	append("error_description", "client_id is missing")
}.formUrlEncode()
```

Edit: updated the documentation to reflect this and make it easier to discover: <https://github.com/ktorio/ktorio.github.io/commit/f5d5039bdfe8387312e7e10633654fe66c334359>

Edit2: just noticed that you solved this already in the next thread :slightly_smiling_face: so just ignore this

Edit3: documented what you commented in the next thread too: <https://github.com/ktorio/ktorio.github.io/commit/4c224a474811778e930862b1c670851e9bd5e8b6>