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:
gem 'valkyrie'
And then execute:
$ bundle
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
Valkyrie::MetadataAdapter.register(
Valkyrie::Persistence::Postgres::MetadataAdapter.new,
:postgres
)
# To use the solr adapter you must add gem 'rsolr' to your Gemfile
Valkyrie::MetadataAdapter.register(
Valkyrie::Persistence::Solr::MetadataAdapter.new(
connection: Blacklight.default_index.connection
),
:solr
)
# To use the fedora adapter you must add `gem 'ldp'` to your Gemfile
Valkyrie::MetadataAdapter.register(
Valkyrie::Persistence::Fedora::MetadataAdapter.new(
connection: ::Ldp::Client.new("http://localhost:8988/rest"),
base_path: "test_fed",
schema: Valkyrie::Persistence::Fedora::PermissiveSchema.new(title: RDF::URI("http://bad.com/title"))
),
:fedora
)
Valkyrie::MetadataAdapter.register(
Valkyrie::Persistence::Memory::MetadataAdapter.new,
:memory
)
Valkyrie::StorageAdapter.register(
Valkyrie::Storage::Disk.new(base_path: Rails.root.join("tmp", "files")),
:disk
)
Valkyrie::StorageAdapter.register(
Valkyrie::Storage::Fedora.new(connection: Ldp::Client.new("http://localhost:8988/rest")),
:fedora
)
Valkyrie::StorageAdapter.register(
Valkyrie::Storage::Memory.new,
:memory
)
end
The initializer registers four Valkyrie::MetadataAdapter
instances for storing metadata:
:fedora
which stores metadata in a Fedora server.:memory
which stores metadata in an in-memory cache (this cache is not persistent, so it is only appropriate for testing).:postgres
which stores metadata in a PostgreSQL database.:solr
which 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
at once, Valkyrie::Persistence::Solr
for storing in Solr, and Valkyrie::Persistence::Fedora
for storing
in Fedora.
The initializer also registers three Valkyrie::StorageAdapter
instances for storing files:
:disk
which stores files on disk:fedora
which stores files in Fedora:memory
which stores files in an in-memory cache (again, not persistent, so this is only appropriate for testing)
require 'valkyrie'
Rails.application.config.to_prepare do
Valkyrie.config.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_adapter
is the store where Valkyrie will put the metadatastorage_adapter
is 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 class:
# frozen_string_literal: true
class MyModel < Valkyrie::Resource
include Valkyrie::Resource::AccessControls
attribute :title, Valkyrie::Types::Set # Sets deduplicate values
attribute :date, Valkyrie::Types::Array # 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, Valkyrie::Types::Array.meta(ordered: true)
Defining resource attributes is explained in greater detail on the Using Types Wiki page.
# initialize a metadata adapter
adapter = Valkyrie::MetadataAdapter.find(: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
Valkyrie.config.metadata_adapter.query_service.find_all_of_model(model: MyModel)
The Wiki documents the usage of Queries, Persistence, and ChangeSets and Dirty Tracking.
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.
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.
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.:
Valkyrie::Storage::Fedora.new(
connection: Ldp::Client.new("http://fedoraAdmin:fedoraAdmin@localhost:8988/rest"),
fedora_version: 5
)
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 install
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/.
If you're working on PR for this project, create a feature branch off of main
.
This repository follows the Samvera Community Code of Conduct and language recommendations. Please do not create a branch called master
for this repository or as part of your pull request; the branch will either need to be removed or renamed before it can be considered for inclusion in the code base and history of this repository.