How to Post Data to URL in Flutter WebView

flutter post webview

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Solution 1

webview_flutter doesn't have a method to send post requests at this moment. However, you can try my flutter_inappwebview plugin. It supports POST requests!

A simple example using the current latest version 5.0.5+3 of the flutter_inappwebview plugin is:

var postData = Uint8List.fromList(utf8.encode("firstname=Foo&lastname=Bar"));
controller.postUrl(url: Uri.parse("https://example.com/my-post-endpoint"), postData: postData);

where the postData is the Body of the request in x-www-form-urlencoded format.

For example, if you have a PHP server, you can access the firstname and lastname values as you normally would do, that is $_POST['firstname'] and $_POST['lastname'].

You can also initialize the InAppWebView widget with an initial POST request like this:

child: InAppWebView(
  initialUrlRequest: URLRequest(
    url: Uri.parse("https://example.com/my-post-endpoint"),
    method: 'POST',
    body: Uint8List.fromList(utf8.encode("firstname=Foo&lastname=Bar")),
    headers: {
      'Content-Type': 'application/x-www-form-urlencoded'
    }
  ),
  onWebViewCreated: (controller) {
    
  },
),

Solution 2

You can run JS functions on official Flutter WebView ::

1-Example of Post request by JS

**
 * sends a request to the specified url from a form. this will change the window location.
 * @param {string} path the path to send the post request to
 * @param {object} params the parameters to add to the url
 * @param {string} [method=post] the method to use on the form
 */

function post(path, params, method='post') {

  // The rest of this code assumes you are not using a library.
  // It can be made less verbose if you use one.
  const form = document.createElement('form');
  form.method = method;
  form.action = path;

  for (const key in params) {
    if (params.hasOwnProperty(key)) {
      const hiddenField = document.createElement('input');
      hiddenField.type = 'hidden';
      hiddenField.name = key;
      hiddenField.value = params[key];

      form.appendChild(hiddenField);
    }
  }

  document.body.appendChild(form);
  form.submit();
}

2-Convert JS function to a String in Flutter and Call that

final String postUrl="'https://jsonplaceholder.typicode.com/posts'";
final String postParam= "{name: 'Johnny Bravo'}";
final String requestMethod= "'post'";

final  String jsFunc="function post(path, params, method='post') {"+
    "const form = document.createElement('form');"+
    "form.method = method;"+
    "form.action = path;"+
    "for (const key in params) {"+
    "if (params.hasOwnProperty(key)) {"+
    "const hiddenField = document.createElement('input');"+
    "hiddenField.type = 'hidden';"+
    "hiddenField.name = key;"+
    "hiddenField.value = params[key];"+
    "form.appendChild(hiddenField);}}document.body.appendChild(form);form.submit();}"+
    "post($postUrl, $postParam, method=$requestMethod)";

3- Run JS code in WebView

return FutureBuilder<WebViewController>(
    future: _controller.future,
    builder: (BuildContext context,
        AsyncSnapshot<WebViewController> controller) {
      if (controller.hasData) {
        return FloatingActionButton(
          onPressed: () async {
            controller.data!.evaluateJavascript(jsFunc);
          },
          child: const Icon(Icons.call_received),
        );
      }
      return Container();
    });

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