Lesson: adding content datastreams

This lesson is known to work with hydra-head version 6.0.0.
Please update this wiki to reflect any other versions that have been tested.

Goals

• Add "file-bearing" Datastreams to models and objects
• See where files are stored in Fedora objects and how to retrieve them

Explanation

So far, we've only added datastreams that bear metadata. Let's add a datastream that has some content to it. For example, this could be a content datastream in our book model that is an image of the book's cover, or a datastream added to the page model that is an image or pdf of that actual page.

In this case, we'll add a file datastream where we can store a pdf of a page.

Steps

Step 1: Add a "pageContent" file datastream to the Page model

In our Page model app/models/page.rb, we'll add the following line underneath our descMetadata datastream:

has_file_datastream "pageContent"

Now we have a datastream called "pageContent" that can hold any kind of file we wish to add to it.

Step 2: In the console, add a file to a Page object and save it

To add the file to one of our page objects, open up the console again:

 > p = Page.find("changeme:2")
 => #<Page pid:"changeme:2", number:[1], text:["Happy families are all alike; every unhappy family is unhappy in its own way."]> 
 > p.datastreams.keys
 => ["DC", "RELS-EXT", "descMetadata", "pageContent"] 

Now you're ready to add the file. Choose a file on your computer that you want to add as the "pageContent". In the lines below we're pretending that the path to the file is "/Users/adamw/Desktop/page1.pdf". Replace that with the correct local path for the file you want to use.

 > p.pageContent.content = File.open("/Users/adamw/Desktop/page1.pdf")
 => #<File:/Users/adamw/Desktop/page1.pdf> 
 > p.save
 => true

Step 3: See where the file Datastream was saved in Fedora

Now if you go to http://localhost:8983/fedora/objects/changeme:2/datastreams, you'll see the pageContent datastream in Fedora. Following the links to it will allow us to view or download the file we've added.

Next Step

Go on to Lesson: Generate Rails Scaffolding for Creating and Editing Books or return to the Dive into Hydra page.