How can I display a document image in a VisualForce page so it works in a managed package?

Question

I am making a managed package that contains an app that uses a document type image as a logo. I use the same logo on a VisualForce page in the same package, but that file is actually stored as a static resource.

I would like to only include the file once in the package, so I want to delete the static resource image, and simply reference the document image in the VF page.

I read that I can use the tag, and the url should be in the form : " /servlet/servlet.FileDownload?file=xxxxxxxxxxx" where xxxxxxxxxxx is the the unique id of theDocument/Attachment record containing the image.

Would that ID stay the same if I add the image to a managed package and it gets installed on a different org, or would the new org have a copy of the file with a different ID?

Answer 1

No, the ID will not remain the same. You'll need to find the document by using a query, either embedded in a controller, custom label, or custom setting, or by using JavaScript. There's no good way to statically reference a document.

You should prefer the use static resources, not documents, as they are referenced by name, and are available using {!$Resource.resourceName}. Static resources are portable, are namespaced in the case of managed packages, and can be statically referenced.