javascript – Append image file to form data – Cordova/Angular-ThrowExceptions

Exception or error:

I am using Anuglar, Ionic and Cordova in my current project, and I’m trying to POST FormData containing an image file to my server. Right now I’m using the cordova camera plugin to return a file path to the image on the device (ex: file://path/to/img). Once I have the file path I want to append the image file to a FormData object using the images file path. Here is my code right now.

var fd = new FormData();

fd.append('attachment', file);
fd.append('uuid', uuid);
fd.append('userRoleId', userRole);

The code above works when appending a file that is taken from an <input type='file'> but doesn’t work when just given the file path on the device.

Basically the FormData is showing like this right now:

------WebKitFormBoundaryasdf
Content-Disposition: form-data; name="attachment"; 

file://path/to/img

and I want it to look like this

------WebKitFormBoundaryasdf
Content-Disposition: form-data; name="attachment"; filename="jesus-quintana.jpg"
Content-Type: image/jpeg

I found many different ways to upload the image using cordova FileTransfer and by converting the image to a base64 and then uploading it. But I couldn’t find any simple ways of just grabbing the file by using the path and posting it within a form. I’m not very familiar with the File Api so any help would be appreciated

How to solve:

After some fiddling around I manage to figure out a pretty simple solution.
First I added the cordova file plugin then I use the code below

var fd = new FormData();
     window.resolveLocalFileSystemURL(attachment.img, function(fileEntry) {
         fileEntry.file(function(file) {
             var reader = new FileReader();
                 reader.onloadend = function(e) {
                      var imgBlob = new Blob([ this.result ], { type: "image/jpeg" } );
                      fd.append('attachment', imgBlob);
                      fd.append('uuid', attachment.uuid);
                      fd.append('userRoleId', 12345);
                      console.log(fd);
                      //post form call here
                 };
                 reader.readAsArrayBuffer(file);

         }, function(e){$scope.errorHandler(e)});
    }, function(e){$scope.errorHandler(e)});

So I’m just creating a form and using FileReader to insert an ArrayBuffer to the Blob object and then append that to the form data. Hopefully this helps someone else looking for an easy way to do this.

###

You do need to send file content. With the HTML5 FileAPI you need to create a FileReader object.

Some time ago, I developed an application with cordova and I had to read some files, and I made a library called CoFS (first, by Cordova FileSystem, but it’s working in some browsers).

It’s on beta state, but I use it and works well. You can try to do some like this:

var errHandler = function (err) {
   console.log("Error getting picture.", err);
};

var sendPicture = function (file) {

    var fs = new CoFS();

    fs.readFile(file, function (err, data) {

        if (err) {
            return errHandler(err);
        }

        var fd = new FormData();

        fd.append('attachment', new Blob(data));
        fd.append('uuid', uuid);
        fd.append('userRoleId', userRole);

        console.log("Data of file:" + data.toString('base64'));
        // Send fd...

    });

};

navigator.camera.getPicture(sendPicture, errHandler);

Sorry my poor english.

###

Your post was extremly helpful to fix my problem. I’m using Ionic 4 and trying to upload an image using standard http and file client. The key code for reference is here:

return this.file.readAsArrayBuffer(path, file).
  then(blob => {
    const imgBlob = new Blob([blob], { type: 'image/jpeg' } );

    formData.append('image[file]', imgBlob);

    return this.http.post(url, formData, headers).subscribe();
});

Hope it helps someone out there as it did for me.

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