Fetch list item attachment by name

Question

I am trying to write custom code for list item attachments. As it is not allowed to overwrite them, I will check if file already exists. If yes, will delete and then upload again.

I found a method SP.AttachmentCollection.getByFileName Method (sp.js) which can fetch list item by file name. Does anyone has sample code for this?

I am not able to find any documentation on this.

Answer 1

You can simply invoke a REST call to following URL

/_api/lists/getByTitle('ListTitle')/getItemById(1)/AttachmentFiles/getByFileName('filename')

Then check the response to see if file exists or not.

JSOM

function onSuccess(sender, args) {
    var item = listItem;
    var total = item.get_attachmentFiles().get_count();
    if (total > 0) {
        console.log(total + " file attachments");

        //Attachment exists and no need to re attach
    }       
}

function onFailure(sender, args) {
    //failed
}

var clientContext = SP.ClientContext.get_current();
var list = clientContext.get_web().get_lists().getByTitle("ListTitle");
var listItem = list.getItemById(1);
clientContext.load(listItem);
clientContext.load(listItem.get_attachmentFiles().getByFileName("FileName"));
clientContext.executeQueryAsync(Function.createDelegate(this, onSuccess), Function.createDelegate(this, onFailure));