http post a map object using application/json content-type

[DartBot]

Originally opened as dart-lang/sdk#17636

This issue was originally filed by [email protected]

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I am encountering a problem trying to use the "package:http/http.dart' pub package to post some JSON data to a web service. I have formatted the data correctly (which I confirmed by posting using the Advanced REST Client extension for Chrome) and the only difference is the Content-Type is forced to the wrong type (the web service only accepts "application/json"):

If body is a Map, it's encoded as form fields using encoding. The content-type of the request will be set to "application/x-www-form-urlencoded"; this cannot be overridden.

The documentation suggests:

For more fine-grained control over the request, use Request or StreamedRequest instead.

Why is the post content type limited to only form-urlencoded? Can the pub package be fixed to set the content type dynamically?

[DartBot]

<img src="https://avatars.githubusercontent.com/u/1343914?v=3" align="left" width="48" height="48"hspace="10"> Comment by sgjesse

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Added Area-Pkg, Pkg-Http, Triaged labels.

[DartBot]

<img src="https://avatars.githubusercontent.com/u/188?v=3" align="left" width="48" height="48"hspace="10"> Comment by nex3

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The auto-encoding of Maps for [body] is just utility functionality; it makes it easier to do the common case (sending form parameters) without cutting off other possibilities. You can always post arbitrary data by passing [body] a string or a List<int>. For example:

    http.post(url,
        body: JSON.encode(data),
        headers: {'content-type': 'application/json'}));

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Added NotPlanned label.

[efroim102]

Is there anyway to POST json with a property that has an array value? I've been trying to send a json object to a server which works unless I add a property with the value of array (a dart List) or a property with an int property.

[ghost]

@efroim102, as a general rule please open a new issue instead of reviving long dead threads.

To answer your question though, http.post(..) in itself does not handle JSON.
You can however use something like the example from above to post JSON encoded data.
Please refer to the JSON guide for how to encode and decode JSON in Dart.

[efroim102]

@cskau-g Thanks, I was able to resolve this issue using a HttpClient from the dart:io package and using jsonEncode on a Map<String, dynamic> before writing it to the HttpClientRequest stream.