Canvas -> Base64 post to Facebook - facebook

Question

I have implemented a pure javascript function for sharing canvas content to an user's facebook wall. The implementation works, but the problem is:
Facebook does not approve the app, stating after review:
"publish_actions on Web - Your app's users must enter all content
in the user message field. Don't auto-populate the message field with
any content, including links and hashtags, even if you allow users to
edit the content before sharing. Watch this informational video for
more information, and see Platform Policy 2.3"
Afaik, there is no way to pass a base64 object through the FB.ui feed share dialogue with client side javascript only.
Question: Any workarounds or other ways go get a client side only canvas -> facebook share implementation that is passed by the Facebook app approval process?
The current implementation is as follows:
document.getElementById('facebook-link').onclick=function(){
FB.login(function (response) {
if (response.authResponse) {
window.authToken = response.authResponse.accessToken;
PostImageToFacebook(window.authToken);
} else {
}
}, {
scope: 'publish_actions'
});
};
function PostImageToFacebook(authToken) {
var imageData = canvas.toDataURL("image/png");
try {
blob = dataURItoBlob(imageData);
}
catch (e)
{
console.log(e);
}
var fd = new FormData();
fd.append("access_token", authToken);
fd.append("source", blob);
try {
$.ajax({
url: "https://graph.facebook.com/me/photos?access_token=" + authToken,
type: "POST",
data: fd,
processData: false,
contentType: false,
cache: false,
success: function (data) {
console.log("success " + data);
},
error: function (shr, status, data) {
alert.log("error " + data + " Status " + shr.status);
},
complete: function () {
console.log("Posted to facebook");
$('#facebook-link').text('Ferdig delt :)').removeClass( "inProgress" );
}
});
} catch (e) {
console.log(e);
}
}
The implementation does not append any text, making me wonder why it does not comply with the Facebook Platform Policy section 2.3.

Answer 1

I had the same problem in an application. Although we have chosen to use the database, I believe it has a solution to your problem.
Really has no way to share a Base64 code by FB.Ui
But as the policies of Facebook, you are not required to use it.
You can create a custom dialog window for the user to view the image that is being posted and enter/confirm the message, and posting after this action.
As the explanatory video from Facebook, the message posted by the user can not be changed, then it should be approved without problems.