Reliably get attachments for list item

Question

I'm working with SP2010's SP.js and I need to get all the attachments of a list item. As it's SP2010, I don't have access to SP.ListItem's attachmentFiles property. :(

The following code works for this purpose:

var attachmentFolder = clientContext.get_web().getFolderByServerRelativeUrl('/sites/MySite/Lists/MyList/Attachments/' + itemID);
var attachmentFiles = attachmentFolder.get_files();

clientContext.load(attachmentFiles);
clientContext.executeQueryAsync(
    function () {

        var myAttachments = [];
        for (var i = 0; currentItem = attachmentFiles.get_item(i) ; i++)
        {
            myAttachments.push({
                url: currentItem.get_serverRelativeUrl(),
                name: currentItem.get_name()
            });
        }
    },
    function(error) {
        alert("Something has failed magnificently! " + error);
    }
);

The issue is that if the list item has no attachments, sp.js throws a "File Not Found" exception into my error callback. Not pictured in the code sample I included, I'm requesting a few other things in this JSOM query, so my solution is unfortunately not as simple as assuming that an error being returned means that no attachments were found. I don't want my lack of attachments to screw up my other logic.

I tried using a method similar to the following:

var query = SP.CamlQuery.createAllItemsQuery();
query.set_folderServerRelativeUrl(folderServerRelativeUrl);
allItems = list.getItems(query);

but it always returns 0 results, even when attachments are present, so I'm assuming that this CAML query only works on folders that are part of a proper library, not backend folders.

I really don't want to have to make an extra request.

Any ideas?

Answer 1

Using SharePoint 2010 JSOM i would suggest the following approach to retrieve list item attachments:

• determine whether List Item contains attachments or not via ListItem.Attachments property
• in case if list List Item contains attachments, submit a second request to retrieve attachment files

Example

function getListItemAttachments(listTitle,itemId,success,error)
{
   var ctx = SP.ClientContext.get_current();
   var list = ctx.get_web().get_lists().getByTitle(listTitle);
   var item = list.getItemById(itemId);
   ctx.load(item);
   ctx.executeQueryAsync(
      function() {
          var hasAttachments = item.get_fieldValues()['Attachments'];
          if(hasAttachments){
              getAttachmentFiles(item,success,error);
          }
          else
            success([]);
      },
      error);
}



function getAttachmentFiles(listItem,success,error) {
    var ctx = listItem.get_context();
    var attachmentFolderUrl = String.format('{0}/Attachments/{1}',listItem.get_fieldValues()['FileDirRef'],listItem.get_fieldValues()['ID']);
    var folder = ctx.get_web().getFolderByServerRelativeUrl(attachmentFolderUrl);
    var files = folder.get_files();
    ctx.load(files);
    ctx.executeQueryAsync(
       function () {
          var attachments = [];
          for (var i = 0; file = files.get_item(i) ; i++)
          {
              attachments.push({url: file.get_serverRelativeUrl(), name: file.get_name()});
          } 
          success(attachments);      
    },
    error);
}

Usage

getListItemAttachments('Requests',1, 
    function(attachmentFiles){
       console.log(attachmentFiles);
    },
    function(sendera,args){
       console.log(args.get_message());
    });

Answer 2

Check if your list does have attachments enabled?

This can be done using Rest API

/getByTitle('<ListName>')/items?$filter=substringof('Item', Title)
&$select=AttachmentFiles,Title&$expand=AttachmentFiles&$top=4&$orderby=Title"