Uploading Attachments to SharePoint Lists Using REST

In a previous post, I walked through Uploading Attachments to SharePoint Lists Using SPServices. Well, in the “modern” world, I want to use REST whenever I can, especially with SharePoint Online.

Add an attachmentI ran into a challenge figuring out how to make an attachment upload work in an AngularJS project. There are dozens of blog posts and articles out there about uploading files to SharePoint, and some of them even mention attachments. But I found that not a single one of the worked for me. It was driving me nuts. I could upload a file, but it was corrupt when it got there. Images didn’t look like images, Excel couldn’t open XLSX files, etc.

I reached out to Julie Turner (@jfj1997) and asked for help, but as is often the case, when you’re not as immersed in something it’s tough to get the context right. She gave me some excellent pointers, but I ended up traversing some of the same unfruitful ground with her.

Finally I decided to break things down into the simplest example possible, much like I did in my earlier post with SOAP. I created a test page called UploadTEST with a Content Editor Web Part pointing to UploadText.html, below:

<script type="text/javascript" src="https://cdnjs.cloudflare.com/ajax/libs/jquery/2.2.3/jquery.js"></script>

<input id="my-attachments" type="file" fileread="run.AttachmentData" fileinfo="run.AttachmentInfo" />

<script type="text/javascript" src="/sites/MySiteCollection/_catalogs/masterpage/_MyProject/js/UploadTEST.js"></script>

Like I said, I wanted to keep it simple. Here’s what I’m doing:

  • In line 1, I load a recent version of jQuery from cdnjs. On the theory that Angular just adds another layer of complexity, I wanted to try just jQuery, which is useful for its $.ajax function, among many other things.
  • In line 3, I’ve got an input field with type=”file”. In “modern” browsers, this gives us a familiar file picker.
  • In line 5, I’m loading my script file called UploadTest.js, below:
$(document).ready(function() {

 var ID = 1;
 var listname = "UploadTEST";

 $("#my-attachments").change(function() {

  var file = $(this)[0].files[0];

  var getFileBuffer = function(file) {

   var deferred = $.Deferred();
   var reader = new FileReader();

   reader.onload = function(e) {
    deferred.resolve(e.target.result);
   }

   reader.onerror = function(e) {
    deferred.reject(e.target.error);
   }

   reader.readAsArrayBuffer(file);

   return deferred.promise();
  };

  getFileBuffer(file).then(function(buffer) {

   $.ajax({
    url: _spPageContextInfo.webAbsoluteUrl +
     "/_api/web/lists/getbytitle('" + listname + "')/items(" + ID + ")/AttachmentFiles/add(FileName='" + file.name + "')",
    method: 'POST',
    data: buffer,
    processData: false,
    headers: {
     "Accept": "application/json; odata=verbose",
     "content-type": "application/json; odata=verbose",
     "X-RequestDigest": document.getElementById("__REQUESTDIGEST").value,
     "content-length": buffer.byteLength
    }
   });

  });

 });
});

Here’s how this works – and yes, it does work!

  • I’ve got everything wrapped in a $(document).ready() to ensure the page is fully loaded before my script runs.
  • Lines 3-4 just set up some variables I could use for testing to keep things simple.
  • In line 6, I bind to the change event for the input field. Whenever the user chooses a file in the dialog, this event will fire.
  • In line 8, I’m getting the information about the file selected from the input element.
  • Lines 10-26 is the same getFileBuffer function I used with SOAP; it’s where we use a FileReader to get the contents of the selected file into a buffer.
  • The function in lines 28-42 runs when the file contents have been fully read. The getFileBuffer function returns a promise, and that promise is resolved when the function has gotten all of the file contents. With a large file, this could take a little while, and by using a promise we avoid getting ahead of ourselves. Here we make the REST call that uploads the attachment.
    • The URL ends up looking something like: “/my/site/path/_api/web/lists/getbytitle(‘UploadTEST’)/items(1)/AttachmentFiles/add(FileName=’boo.txt’)”
    • The method is a POST because we’re writing data to SharePoint
    • The data parameter contains the “payload”, which is the buffer returned from the getFileBuffer function.
    • The headers basically tell the server what we’re up to:
      • Accept doesn’t really come into play here unless we get a result back, but it says “send me back json and be verbose”
      • content-type is similar, but tells the server what it is getting from us
      • X-RequestDigest is the magic string from the page that tells the server we are who it thinks we are
      • content-length tells the server how many bytes it should expect

This worked for me on a basic Custom List (UploadTEST). So now I knew it was possible to upload an attachment using REST.

I took my logic and shoved it back into my AngularJS page, and it still worked! However, when I switched from $.ajax to AngularJS’s $http, I was back to corrupt files again. I’m still not sure why that is the case, but since I’m loading jQuery for some other things, anyway, I’ve decided to stick with $.ajax for now instead. If anyone reading this has an idea why $http would cause a problem, I’d love to hear about it.

Once again, I’m hoping my beating my head against this saves some folks some time. Ideally there would be actual documentation for the REST endpoints that would explain how to do things. Unfortunately, if there is for this, I can’t find it. I’d also love to know if /add allows any other parameters, particularly whether I can overwrite the attachment if one of the same name is already there. Maybe another day.

Advertisements

Uploading Attachments to SharePoint Lists Using SPServices

Easy!For years people have been asking me how they could upload files using SPServices. I’ve dodged the questions every time because I simply didn’t know how.

On a current client project,  I’m building a slick Single Page Application (SPA) to manage tasks in SharePoint 2010. It’s basically a veneer over the clunky out-of-the-box task list experience. Rather than hopping from page to page, the team using the application can accomplish everything they need to do on a single page.

Every project has specific needs, and for this one I’m using KnockoutJS. But the code snippets I give below are generic enough that you should be able to use them in any context with a little thinking.

It’s been going well, but I had been putting off implementing adding attachments because…well, as I said, I didn’t know how.

One of the benefits of the shift from all server side development to a much more significant focus on client side techniques is that some of the bright minds in the SharePoint development community have turned their eyes toward solving these things, too. Usually it’s on SharePoint 2013 or SharePoint Online at Office 365. However, at least now when I search for “SharePoint JavaScript xxx”, there are likely to be some great hits I can learn from.

In this case, there were two excellent posts, one from James Glading and one from Scot Hillier. (See the Resources section below for links.)

The first step is to enable HTML5 capabilities in IE10. This requires two small changes to the master page. This seems simple, but it can have effects that you don’t expect. In other words, don’t consider this just a “no brainer”. You need to plan for the change across your Site Collection and any impacts it may have.

The first change is to switch from using “XHTML 1.0” to “HTML” as the DOCTYPE. This is what “turns on” HTML5.

<!DOCTYPE html>

Then, in this project we set the content meta tag to IE=10 because we want to aim for IE10.

<meta http-equiv="X-UA-Compatible" content="IE=10"/>

If your browser base is different, you can, of course, set this differently. In this project, we will require all users of the application to be running IE10 or greater. Firefox and Chrome have supported the bits of HTML5 we need for so long, that there’s little concern about people who choose to use those browsers.

Once we have those two small changes in the master page (we are using a copy of v4.master with no other customizations at the moment), we “have HTML5”. It’s most obvious because some of the branding flourishes I’ve put in like rounded corners show up in IE10 now, rather than just square boxes.

Once we have HTML5 enabled, we can start to use the File API, a.k.a. the FileReader. This is such a simple little thing, that it’s hard to believe it gives us the capability it does.

<input type="file" id="attachment-file-name"/>

That’s it. That simple HTML gives us a file picker on the page. Depending on your browser, it will look something like this:

File Picker

When you make a file selection with this very familiar widget, you can query the element using jQuery.

var file = $("#attachment-file-name").files[0];

Note that we’re after a single file, so we grab the first object in the file list array. We get an object that looks something like this screen shot from Firebug:

File object from the File Picker

Once we have the file object, we can look at what the Lists SOAP Web Service needs to get in order to upload the file. Again, it’s pretty simple. Here is the list of inputs and output from the MSDN documentation page for the Lists.AddAttachment Method.

Parameters

listName
A string that contains either the title or the GUID for the list.
listItemID
A string that contains the ID of the item to which attachments are added. This value does not correspond to the index of the item within the collection of list items.
fileName
A string that contains the name of the file to add as an attachment.
attachment
A byte array that contains the file to attach by using base-64 encoding.

Return Value

A string that contains the URL for the attachment, which can subsequently be used to reference the attachment.

The first three inputs are straightforward. We pass in the name of the SharePoint list, the ID of the list item, and the name of the file we want to attach. It’s that last input parameter called “attachment” that’s a bit tricky.

When we upload a file via an HTTP POST operation – which is what all of the SOAP Web Services use – we have to pass text. But the files we want to upload are as likely as not to be binary files. That’s where the Base64 format comes in. Believe me, you don’t need to know exactly what the format actually is, but you should probably understand that it enables us to send binary files as text bytes. Those bytes are then decoded on the server end so that the file can be stored in all of its original, pristine glory.

Here’s the code I ended up with, skinnied down as much as possible to make it a little clearer to follow. I draw heavily from Scot and James’ posts for this, but nuanced for SPServices. I’ve also stripped out all of the error handling, etc.

  • First, the getFileBuffer function reads the contents of the file into the FileReader buffer. readAsArrayBuffer is an asynchronous method, so we use a jQuery Deferred (promise) to inform the calling function that the processing is done.
  • The contents of the buffer are then converted from an ArrayBuffer – which is what the FileReader gives us – into a Base64EncodedByteArray. This works by passing the buffer through a Uint8Array along the way.
  • Finally, we use the toBase64String method to convert the SP.Base64EncodedByteArray to a Base64String.

Yeah, that’s a lot to swallow, but again, you don’t really need to understand how it works. You just need to know that it does work.

Finally, we call Lists.AddAttachment using SPServices to do the actual upload.

/* From Scot Hillier's post:
http://www.shillier.com/archive/2013/03/26/uploading-files-in-sharepoint-2013-using-csom-and-rest.aspx */
var getFileBuffer = function(file) {

  var deferred = $.Deferred();
  var reader = new FileReader();

  reader.onload = function(e) {
    deferred.resolve(e.target.result);
  }

  reader.onerror = function(e) {
    deferred.reject(e.target.error);
  }

  reader.readAsArrayBuffer(file);

  return deferred.promise();
};

getFileBuffer(file).then(function(buffer) {
  var bytes = new Uint8Array(buffer);
  var content = new SP.Base64EncodedByteArray(); //base64 encoding
  for (var b = 0; b < bytes.length; b++) {
    content.append(bytes[b]);
  }

  $().SPServices({
    operation: "AddAttachment",
    listName: "Tasks",
    listItemID: taskID,
    fileName: file.name,
    attachment: content.toBase64String()
  });

});

Very cool! And as I tweeted yesterday, far easier than I ever would have expected. Yes, it took me a good chunk of a day to figure out, but it definitely works, and pretty fast, too.

If you use this example as a base, you could fairly easily build out some other file uploading functions. Combined with the other attachment-oriented methods in the Lists Web Services, you can also build the other bits of the attachment experience:

  • GetAttachmentCollection – Returns a list of the lit item’s attachments, providing the full path to each that you can use in a list of links.
  • DeleteAttachment – Once you’ve uploaded an attachment and realized it was the wrong one, this method will allow you to delete it.

Moral of the story: Fear not what you do not know. Figure it out.

Resources

What’s the Story for HTML5 with SharePoint 2010? by Joe Li

Uploading Files Using the REST API and Client Side Techniques by James Glading

Uploading Files in SharePoint 2013 using CSOM and REST by Scot Hillier

Lists.AddAttachment Method

This article was also published on IT Unity on Jun 02, 2014. Visit the post there to read additional comments.

Update 2014-05-28 11:55 GMT-5

Hugh Wood (@HughAJWood) took one look at my code above and gave me some optimizations. Hugh could optimize just about anything; he is *very* good at it. I *think* I can even see the difference with larger files.

getFileBuffer(file).then(function(buffer) {
  var binary = "";
  var bytes = new Uint8Array(buffer);
  var i = bytes.byteLength;
  while (i--) {
    binary = String.fromCharCode(bytes[i]) + binary;
  }
  $().SPServices({
    operation: "AddAttachment",
    listName: "Tasks",
    listItemID: taskID,
    fileName: file.name,
    attachment: btoa(binary)
  });
});