Return a list of attachments for a custom object

Question

I'm looking at the following example to upload some attachments to a custom object,

http://blog.jeffdouglas.com/2010/04/28/uploading-an-attachment-using-visualforce-and-a-custom-controller/

It works perfectly, but I'm now looking to reverse the process and return all these attachments and display them in a list or a table or anything.

I'm not really sure where to begin. I'm assuming I need to add anew method in the controller which will run when the page loads, but again I'm a little unsure how to approach this.

Any advice or suggestions would be greatly appreciated.

Answer 1

You can add a property to the controller that returns the collection of attachments using the "lazy load" pattern like this:

public Attachment[] attachments {
    get {
        if (attachments == null) {
            attachments = [
                    select Id, Name, Description, LastModifiedDate
                    from Attachment
                    where ParentId = :customObjectId
                    order by Name
                    ];
        }
        return attachments;
    }
    private set;
}

and use e.g. an apex:pageBlockTable to display the attachment fields as apex:columns.

If you want to have a "View" link in your table that opens the attachment in another tab/window, and don't mind relying on a URL that Salesforce may change in the future, this will work (assuming item is an Attachment):

<apex:outputLink
        styleClass="actionLink"
        target="_BLANK"
        value="/servlet/servlet.FileDownload?file={!item.Id}"
        >View</apex:outputLink>

Do not query the Body of the attachments as you cannot display that (in general) and you will run the risk of exceeding the allowed heap space in your controller.