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In certain cases, you may wish to change the nature or behaviour of Collection Objects in Islandora. By creating a custom collection object, you can override the default behaviour of Islandora. A simplified overview of Collection Objects is provided in the introduction of this guide. For example, you can return objects that have a different relationship to the collection object, you can present objects in your collection in a custom way to your viewer, and you can create security policies that will restrict access to the items in your collection (overriding Fedora's Fedora’s default behaviour). The following chapter provides more information about the default behavior of Islandora, how Collection Objects can be constructed, and how they can be extended and customized.

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A Collection Object can have four Datastreams, although the COLLECTION_POLICY is the only mandatory stream. If you do not have a COLLECTION_POLICY Datastream, additional objects cannot be ingested as members of that collection object. In other words, in order to add items to a collection or sub-collection, the collection object (or "parent“parent-type" type” object) must have a COLLECTION_POLICY stream. Here is an example of a COLLECTION_POLICY Datastream (as viewed using the Islandora interface to view in a browser)

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If you wish to create a new COLLECTION_POLICY stream, you will be writing XML. One way to do this is to start with an example collection policy (there is one available in....) and edit it. The DSID of this datastream must be COLLECTION_POLICY.

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A QUERY Datastream is an ITQL query that overrides the Islandora's Islandora’s default ITQL query. If you have declared different relationships (not a hasModel relationship) in your COLLECTION_POLICY Datastream, you will have to write a custom QUERY stream to return these relationships. In order to do this, you will have to have an understanding of ITQL. Resources for learning ITQL are offered in the Bibliography for this guide. Your ITQL query must return SPARQL XML to be parsed by the default collection view xslt file, or by a custom COLLECTION_VIEW xslt that you have written yourself.

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When you write a CHILD_SECURITY stream you are writing a XACML policy. That XACML policy must be parseable (usable) by Islandora's Islandora’s simple parser. Islandora's Islandora’s simple parser expects the CHILD_SECURITY Datastream to contain a XACML policy that denies access to all users, and then provides exceptions for users with certain Drupal Roles, or User IDs. If users have IDs or roles that are permitted access in the XACML policy, they will be allowed to ingest, view, or modify elements in that collection. You can visit an annotated sample XACML policy in the Resources section of this document. This document can act as a starting point for a collection-object CHILD_SECURITY Datastream.

Creating Custom Islandora Content Models

Islandora makes available a number of Content Model Objects in Islandora Solution Packs. However, you may wish to modify these Content Models, or create your own in order to address particular types of content, or to create custom transformations of your data on ingest. Most of the time, you will customize or write a content model to modify behaviour when users view content, or to mofiy what happens to an object when it is ingested into the repository. Islandora Content Models extend Fedora's Fedora’s Content Model Architecture (CMA), by adding an ISLANDORACM stream.

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Here, we have given it a type = "text"“text”, which in the default schema is analyzed. 

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Once we have created a field named language to store the unanalyzed data in, we'll we’ll use copyField to copy the dwc.language field into the language field which will happen during indexing before it is analyzed. Notice the type is now defined as a string. We can now use these fields in solr request handlers.  Request handlers determine what fields to search and what to return, and you can assign certain fields more weight than others.

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In the qf , we are searching fields like dwc.type and dwc.language and they are all weighted the same. We can tweak the weights later if we wish to customize the results. Solr returns are the fields in <str name="fl"> ”fl”> element.  This gives us nice values to use when displaying the results and when listing facets.

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The XML Forms Builder allows you to create and manipulate xml form templates and affiliate them with content models. This means you can create custom forms for users to ingest items into collection by affiliating the content model with a form. You may want to create a custom metadata form to address the needs of your particular collection, or to pre-populate repeating fields. For example, if a collection of PDFs was all written by the same author, you may wish to create a custom form for this collection that has the author's author’s name pre-populated, so that users ingesting into this collection will not need to re-enter this information. Using custom forms you can also specify which metadata elements you wish to use to describe your object, and create validation rules for particular fields, among other features.

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When developing an XML form in the XML Form Builder you'll you’ll need to reference the schema of the metadata format you are working with. Throughout this document we'll we’ll be using the OAI DC metadata schema as an example. The OAI DC XML format is the serialization of Simple Dublin Core metadata descriptions and we'll we’ll be using Dublin Core elements in this example . You can view/retrieve the schema from here

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In the Create Form dialogue enter a form name - for example we are creating a basic OAI DC form so a name like oai_dc_basic would be appropriate. If you have an existing XML Form Builder form you could upload the form definition. We'll We’ll be creating this OAI DC XML form from scratch, so we can click on Create.

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When creating an XML form the first thing you need to set in the Form Editor is the Form Properties. This is where having an example of an OAI DC record would come in handy and would provide the information you need to fill in the Form Properties. Here is the part of the record that you'll you’ll use:

<oai_dc:dc xmlns:oai_dc="http://www.openarchives.org/OAI/2.0/oai_dc/" xmlns:dc="http://purl.org/dc/elements/1.1/"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://www.openarchives.org/OAI/2.0/oai_dc/
http://www.openarchives.org/OAI/2.0/oai_dc.xsd">

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Some schema require elements appear in a certain order (an order based schema), that certain elements be required or not, that some elements are repeatable and others not, or that elements can be nested. Refer to your schema documentation and to the guidance in creation of records based on the schema. For the schema we are using in this tutorial, Simple Dublin Core, each of the fifteen elements is optional and may be repeated. We will create a simple form for this exercise that utilizes several Dublin Core elements. Let's Let’s create a table listing the elements, the element labels, the type of element, the content of the element, and whether they are repeatable. We'll We’ll use this information when adding elements to our form.

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where /oai_dc:dc is the parent element and dc:title is the child element. The Create dialogue is where we enter the information needed for creating an element in our form. We'll We’ll be entering information into the Path Context, Path, Type, and Value properties in our example. If you had an order based schema, you would also fill in the Schema field. Here are some definitions for each of those properties:

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parent - xpath query is run from the node created/read by its parent's parent’s form field

self - only applies Delete and Update actions and applies to the node selected by the Read action.

Path: An XPATH to this element's element’s parent object. This is used to determine whether this element is inserted.

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Note: you can Update or Delete nodes other than the node which is Read. (for example with mods:name ... … where sub-elements are created with a form field and additional nodes are automatically created with XML code. We may want to delete/update the entire mods:name and its sub-elements.)

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In many cases you will want to provide the user with a list of controlled terms and the select form field type is used. For the type element our controlled list of terms is based on the DCMI Type Vocabulary. The Vocabulary "provides “provides a general, cross-domain list of approved terms that may be used as values for the Resource Type element to identify the genre of a resource"resource”.#

DCMI Type Vocabulary

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Connecting the Form to a Content Model

Once you've you’ve completed and tested the form you've you’ve created in the XML Form Builder module, you can connect that form to an existing content model using the Form Associations module. You can navigate to the module using this path:

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You will be presented with the form that we created during this tutorial. You'll You’ll need to fill it in. Once you've you’ve completed your data entry, submit the form.

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Here is a table of Datastreams, including the Datastream IDs that we've assigned, and the expected mimetype of the Datastreams.

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