Valkyrie is a gem for enabling multiple backends for storage of files and metadata in Samvera.
The Samvera community is here to help. Please see our support guide.
Add this line to your application's Gemfile:
And then execute:
Valkyrie is configured in two places: an initializer that registers the persistence options and a YAML configuration file that sets which options are used by default in which environments.
Here is a sample initializer that registers a couple adapters and storage adapters, in each case linking an instance with a short name that can be used to refer to it in your application:
# frozen_string_literal: true require 'valkyrie' Rails.application.config.to_prepare do # To use the postgres adapter you must add `gem 'pg'` to your Gemfile ::.( ::::::.new, :postgres ) # To use the solr adapter you must add gem 'rsolr' to your Gemfile ::.( ::::::.( connection: Blacklight.default_index.connection ), :solr ) # To use the fedora adapter you must add `gem 'ldp'` to your Gemfile ::.( ::::::.( connection: ::Ldp::Client.new("http://localhost:8988/rest"), base_path: "test_fed", schema: ::::::.(title: ::("http://bad.com/title")) ), :fedora ) ::.( ::::::.new, :memory ) ::.( ::::.(base_path: Rails.root.join("tmp", "files")), :disk ) ::.( ::::.(connection: Ldp::Client.new("http://localhost:8988/rest")), :fedora ) ::.( ::::., :memory ) end
The initializer registers four
Valkyrie::MetadataAdapter instances for storing metadata:
:fedorawhich stores metadata in a Fedora server.
:memorywhich stores metadata in an in-memory cache (this cache is not persistent, so it is only appropriate for testing).
:postgreswhich stores metadata in a PostgreSQL database.
:solrwhich stores metadata in a Solr Index (Solr Persister issues a warning if it has to generate an ID for a new resource because it is intended to be used as a secondary persister).
Other adapter options include
Valkyrie::Persistence::BufferedPersister for buffering in memory before bulk
updating another persister,
Valkyrie::Persistence::CompositePersister for storing in more than one adapter
Valkyrie::Persistence::Solr for storing in Solr, and
Valkyrie::Persistence::Fedora for storing
The initializer also registers three
Valkyrie::StorageAdapter instances for storing files:
:diskwhich stores files on disk
:fedorawhich stores files in Fedora
:memorywhich stores files in an in-memory cache (again, not persistent, so this is only appropriate for testing)
Sample configuration with custom
require 'valkyrie' Rails.application.config.to_prepare do ..resource_class_resolver = lambda do |resource_klass_name| # Do complicated lookup based on the string end end
A sample configuration file that configures your application to use different adapters:
development: metadata_adapter: postgres storage_adapter: disk test: metadata_adapter: memory storage_adapter: memory production: metadata_adapter: postgres storage_adapter: fedora
For each environment, you must set two values:
metadata_adapteris the store where Valkyrie will put the metadata
storage_adapteris the store where Valkyrie will put the files
The values are the short names used in your initializer.
Further details can be found on the Persistence Wiki page.
Define a Custom Work
Define a custom work class:
# frozen_string_literal: true class MyModel < :: include :::: attribute :title, :::: # Sets deduplicate values attribute :date, :::: # Arrays can contain duplicate values end
Attributes are unordered by default. Adding
ordered: true to an attribute definition will preserve the
order of multiple values.
attribute :authors, ::::.(ordered: true)
Defining resource attributes is explained in greater detail on the Using Types Wiki page.
Work Types Generator
To create a custom Valkyrie model in your application, you can use the Rails generator. For example, to
generate a model named
FooBar with an unordered
title field and an ordered
rails generate valkyrie:resource FooBar title member_ids:array
You can namespace your model class by including a slash in the model name:
rails generate valkyrie:resource Foo/Bar title member_ids:array
Read and Write Data
# initialize a metadata adapter adapter = ::.(:postgres) # create an object object1 = MyModel.new title: 'My Cool Object', authors: ['Jones, Alice', 'Smith, Bob'] object1 = adapter.persister.save(resource: object1) # load an object from the database object2 = adapter.query_service.find_by(id: object1.id) # load all objects objects = adapter.query_service.find_all # load all MyModel objects ...query_service.find_all_of_model(model: MyModel)
A Valkyrie repository may have concurrent updates, for example, from a load-balanced Rails application, or from multiple Sidekiq background workers). In order to prevent multiple simultaneous updates applied to the same resource from losing or corrupting data, Valkyrie supports optimistic locking. How to use optimistic locking with Valkyrie is documented on the Optimistic Locking Wiki page.
The Public API
Valkyrie's public API is defined by the shared specs that are used to test each of its core classes. This include change sets, resources, persisters, adapters, and queries. When creating your own kinds of these kinds of classes, you should use these shared specs to test your classes for conformance to Valkyrie's API.
When breaking changes are introduced, necessitating a major version change, the shared specs will reflect this. When new features are added and a minor version is released there will be no change to the existing shared specs, but there may be new ones. These new shared specs will fail in your application if you have custom adapters, but your application will still work.
Using the shared specs in your own models is described in more detail on the Shared Specs Wiki page.
Fedora 5 Compatibility
When configuring your adapter, include the
fedora_version parameter in your metadata or storage adapter
config. If Fedora requires auth, you can also include that in the URL, e.g.:
::::.( connection: Ldp::Client.new("http://fedoraAdmin:[email protected]:8988/rest"), fedora_version: 5 )
Installing a Development environment
For ease of development we use Lando to abstract away some complications of using Docker containers for development.
- Install the latest released > 3.0 version of Lando from here.
bundle exec rake server:start
bundle exec rspec spec
bundle exec rake server:clean
bundle exec rake server:stop
You can also run
lando poweroff from anywhere.
This software has been developed by and is brought to you by the Samvera community. Learn more at the Samvera website.
Bug reports and pull requests are welcome on GitHub at https://github.com/samvera/valkyrie/.