How to POST binary files with AngularJS (with upload DEMO)

June 2, 2022 by Tarik Billa

RECOMMENDED: POST Binary Files Directly

Posting binary files with multi-part/form-data is inefficient as the base64 encoding adds an extra 33% overhead. If the server API accepts POSTs with binary data, post the file directly:

function upload(url, file) {
    if (file.constructor.name != "File") {
       throw new Error("Not a file");
    }
    var config = {
        headers: {'Content-Type': undefined},
        transformRequest: []
    };
    return $http.post(url, file, config)
      .then(function (response) {
        console.log("success!");
        return response;
    }).catch(function (errorResponse) {
        console.error("error!");
        throw errorResponse;
    });
}

Normally the $http service encodes JavaScript objects as JSON strings. Use transformRequest: [] to override the default transformation.

DEMO of Direct POST

angular.module("app",[])
.directive("selectNgFiles", function() {
  return {
    require: "ngModel",
    link: postLink
  };
  function postLink(scope, elem, attrs, ngModel) {
    elem.on("change", function(event) {
      ngModel.$setViewValue(elem[0].files);
    });
  }
})
.controller("ctrl", function($scope, $http) {
  var url = "//httpbin.org/post";
  var config = {
    headers: { 'Content-type': undefined }
  };
  $scope.upload = function(files) {
    var promise = $http.post(url,files[0],config);
    promise.then(function(response){
      $scope.result="Success "+response.status;
    }).catch(function(errorResponse) {
      $scope.result="Error "+errorRespone.status;
    });
  };
})

<script src="https://unpkg.com/angular/angular.js"></script>
  <body ng-app="app" ng-controller="ctrl">
    <input type="file" select-ng-files ng-model="files">
    <br>
    <button ng-disabled="!files" ng-click="upload(files)">
      Upload file
    </button>
    <pre>
    Name={{files[0].name}}
    Type={{files[0].type}}
    RESULT={{result}}
    </pre>
  </body>

Posting with `'Content-Type': 'multipart/form-data'`

When posting data using the FormData API, it is important to set the content type to undefined:

function uploadQuestion(file) {

    var form = new FormData();
    form.append("j_id", "4124");
    form.append("q_id", "6");
    form.append("u_id", "159931");
    form.append("file", file); //this returns media object which contain all details of recorded video

    return $http({
        method: 'POST',
        headers: { 'Content-Type': undefined ̶'̶m̶u̶l̶t̶i̶p̶a̶r̶t̶/̶f̶o̶r̶m̶-̶d̶a̶t̶a̶'̶ }, // also tried with application/x-www-form-urlencoded
        url: 'http://services.example.com/upload.php',
        data: form,
        ̶c̶a̶c̶h̶e̶:̶ ̶f̶a̶l̶s̶e̶,̶ 
        timeout: 300000
    ̶}̶)̶.̶s̶u̶c̶c̶e̶s̶s̶(̶f̶u̶n̶c̶t̶i̶o̶n̶ ̶(̶d̶a̶t̶a̶,̶ ̶s̶t̶a̶t̶u̶s̶,̶ ̶h̶e̶a̶d̶e̶r̶s̶,̶ ̶c̶o̶n̶f̶i̶g̶)̶ ̶{̶
    }).then(function(response) {
        var data = response.data;
        var status = response.status;
        if (status == '200') {
           console.log("Success");
        }    
    ̶}̶)̶.̶e̶r̶r̶o̶r̶(̶f̶u̶n̶c̶t̶i̶o̶n̶ ̶(̶d̶a̶t̶a̶,̶ ̶s̶t̶a̶t̶u̶s̶,̶ ̶h̶e̶a̶d̶e̶r̶s̶,̶ ̶c̶o̶n̶f̶i̶g̶)̶ ̶{̶
    }).catch(function(response) {
        console.log("ERROR");
        //IMPORTANT
        throw response;    
    });
}

When the XHR API send method sends a FormData Object, it automatically sets the content type header with the appropriate boundary. When the $http service overrides the content type, the server will get a content type header without the proper boundary.

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