Class: Gcloud::Datastore::Dataset

Inherits:
Object
  • Object
show all
Defined in:
lib/gcloud/datastore/dataset.rb,
lib/gcloud/datastore/dataset/query_results.rb,
lib/gcloud/datastore/dataset/lookup_results.rb

Overview

Dataset

Dataset is the data saved in a project’s Datastore. Dataset is analogous to a database in relational database world.

Gcloud::Datastore::Dataset is the main object for interacting with Google Datastore. Gcloud::Datastore::Entity objects are created, read, updated, and deleted by Gcloud::Datastore::Dataset.

require "gcloud"

gcloud = Gcloud.new
dataset = gcloud.datastore

query = dataset.query("Task").
  where("completed", "=", true)

tasks = dataset.run query

See Gcloud#datastore

Direct Known Subclasses

Transaction

Defined Under Namespace

Classes: LookupResults, QueryResults

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(project, credentials) ⇒ Dataset

Creates a new Dataset instance.

See Gcloud#datastore



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# File 'lib/gcloud/datastore/dataset.rb', line 55

def initialize project, credentials #:nodoc:
  project = project.to_s # Always cast to a string
  fail ArgumentError, "project is missing" if project.empty?
  @connection = Connection.new project, credentials
end

Instance Attribute Details

#connection ⇒ Object

:nodoc:



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# File 'lib/gcloud/datastore/dataset.rb', line 49

def connection
  @connection
end

Class Method Details

.default_project ⇒ Object

Default project.



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# File 'lib/gcloud/datastore/dataset.rb', line 80

def self.default_project #:nodoc:
  ENV["DATASTORE_DATASET"] ||
    ENV["DATASTORE_PROJECT"] ||
    ENV["GCLOUD_PROJECT"] ||
    ENV["GOOGLE_CLOUD_PROJECT"] ||
    Gcloud::GCE.project_id
end

Instance Method Details

#allocate_ids(incomplete_key, count = 1) ⇒ Object

Generate IDs for a Key before creating an entity.

Parameters

incomplete_key

A Key without id or name set. (Key)

count

The number of new key IDs to create. (Integer)

Returns

Array of Gcloud::Datastore::Key

Example

empty_key = dataset.key "Task"
task_keys = dataset.allocate_ids empty_key, 5



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# File 'lib/gcloud/datastore/dataset.rb', line 107

def allocate_ids incomplete_key, count = 1
  if incomplete_key.complete?
    fail Gcloud::Datastore::Error, "An incomplete key must be provided."
  end

  incomplete_keys = count.times.map { incomplete_key.to_proto }
  response = connection.allocate_ids(*incomplete_keys)
  Array(response.key).map do |key|
    Key.from_proto key
  end
end

#delete(*entities_or_keys) ⇒ Object

Remove entities from the Datastore.

Parameters

entities_or_keys

One or more Entity or Key objects to remove. (Entity or Key)

Returns

true if successful

Example

gcloud = Gcloud.new
dataset = gcloud.datastore
dataset.delete entity1, entity2



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# File 'lib/gcloud/datastore/dataset.rb', line 226

def delete *entities_or_keys
  keys = entities_or_keys.map do |e_or_k|
    e_or_k.respond_to?(:key) ? e_or_k.key.to_proto : e_or_k.to_proto
  end
  mutation = Proto.new_mutation.tap do |m|
    m.delete = keys
  end
  connection.commit mutation
  true
end

#entity(key_or_kind = nil, id_or_name = nil) {|entity| ... } ⇒ Object

Create a new empty Entity instance. This is a convenience method to make the creation of Entity objects easier.

Parameters

key_or_kind

A Key object or kind string value. This is optional. (Key or String or nil)

id_or_name

The Key’s id or name value if a kind was provided in the first parameter. (Integer or String or nil)

Returns

Gcloud::Datastore::Entity

Examples

entity = dataset.entity

This code is equivalent to the following:

entity = Gcloud::Datastore::Entity.new

The key can also be passed in as an object:

key = dataset.key "User", "[email protected]"
entity = dataset.entity key

Or the key values can be passed in as parameters:

entity = dataset.entity "User", "[email protected]"

This code is equivalent to the following:

key = Gcloud::Datastore::Key.new "User", "[email protected]"
entity = Gcloud::Datastore::Entity.new
entity.key = key

The newly created entity object can also be configured using a block:

 user = dataset.entity "User", "[email protected]" do |u|
   u["name"] = "Heidi Henderson"
end

This code is equivalent to the following:

key = Gcloud::Datastore::Key.new "User", "[email protected]"
entity = Gcloud::Datastore::Entity.new
entity.key = key
entity["name"] = "Heidi Henderson"

Yields:



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# File 'lib/gcloud/datastore/dataset.rb', line 444

def entity key_or_kind = nil, id_or_name = nil
  entity = Entity.new

  # Set the key
  key = key_or_kind
  unless key.is_a? Gcloud::Datastore::Key
    key = Key.new key_or_kind, id_or_name
  end
  entity.key = key

  yield entity if block_given?

  entity
end

#find(key_or_kind, id_or_name = nil) ⇒ Object Also known as: get

Retrieve an entity by providing key information.

Parameters

key_or_kind

A Key object or kind string value. (Key or String)

id_or_name

The Key’s id or name value if a kind was provided in the first parameter. (Integer or String or nil)

Returns

Gcloud::Datastore::Entity or nil

Example

Finding an entity with a key:

key = dataset.key "Task", 123456
task = dataset.find key

Finding an entity with a kind and id/name:

task = dataset.find "Task", 123456



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# File 'lib/gcloud/datastore/dataset.rb', line 170

def find key_or_kind, id_or_name = nil
  key = key_or_kind
  unless key.is_a? Gcloud::Datastore::Key
    key = Key.new key_or_kind, id_or_name
  end
  find_all(key).first
end

#find_all(*keys) ⇒ Object Also known as: lookup

Retrieve the entities for the provided keys.

Parameters

keys

One or more Key objects to find records for. (Key)

Returns

Gcloud::Datastore::Dataset::LookupResults

Example

gcloud = Gcloud.new
dataset = gcloud.datastore
key1 = dataset.key "Task", 123456
key2 = dataset.key "Task", 987654
tasks = dataset.find_all key1, key2



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# File 'lib/gcloud/datastore/dataset.rb', line 199

def find_all *keys
  response = connection.lookup(*keys.map(&:to_proto))
  entities = to_gcloud_entities response.found
  deferred = to_gcloud_keys response.deferred
  missing  = to_gcloud_entities response.missing
  LookupResults.new entities, deferred, missing
end

#key(kind = nil, id_or_name = nil) ⇒ Object

Create a new Key instance. This is a convenience method to make the creation of Key objects easier.

Parameters

kind

The kind of the Key. This is optional. (String)

id_or_name

The id or name of the Key. This is optional. (Integer or String)

Returns

Gcloud::Datastore::Key

Example

key = dataset.key "User", "[email protected]"

This code is equivalent to the following:

key = Gcloud::Datastore::Key.new "User", "[email protected]"



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# File 'lib/gcloud/datastore/dataset.rb', line 387

def key kind = nil, id_or_name = nil
  Key.new kind, id_or_name
end

#project ⇒ Object

The Datastore project connected to.

Example

require "gcloud"

gcloud = Gcloud.new "my-todo-project",
                    "/path/to/keyfile.json"

dataset = gcloud.datastore
dataset.project #=> "my-todo-project"



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# File 'lib/gcloud/datastore/dataset.rb', line 74

def project
  connection.dataset_id
end

#query(*kinds) ⇒ Object

Create a new Query instance. This is a convenience method to make the creation of Query objects easier.

Parameters

kinds

The kind of entities to query. This is optional. (String)

Returns

Gcloud::Datastore::Query

Example

query = dataset.query("Task").
  where("completed", "=", true)
tasks = dataset.run query

This code is equivalent to the following:

query = Gcloud::Datastore::Query.new.
  kind("Task").
  where("completed", "=", true)
tasks = dataset.run query



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# File 'lib/gcloud/datastore/dataset.rb', line 358

def query *kinds
  query = Query.new
  query.kind(*kinds) unless kinds.empty?
  query
end

#run(query, namespace: nil) ⇒ Object Also known as: run_query

Retrieve entities specified by a Query.

Parameters

query

The Query object with the search criteria. (Query)

namespace

The namespace the query is to run within. (String)

Returns

Gcloud::Datastore::Dataset::QueryResults

Examples

query = dataset.query("Task").
  where("completed", "=", true)
tasks = dataset.run query

The query can optionally run within namespace when the namespace option is provided:

query = Gcloud::Datastore::Query.new.kind("Task").
  where("completed", "=", true)
tasks = dataset.run query, namespace: "ns~todo-project"



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# File 'lib/gcloud/datastore/dataset.rb', line 264

def run query, namespace: nil
  partition = optional_partition_id namespace
  response = connection.run_query query.to_proto, partition
  entities = to_gcloud_entities response.batch.entity_result
  cursor = Proto.encode_cursor response.batch.end_cursor
  more_results = Proto.to_more_results_string response.batch.more_results
  QueryResults.new entities, cursor, more_results
end

#save(*entities) ⇒ Object

Persist one or more entities to the Datastore.

Parameters

entities

One or more entity objects to be saved without id or name set. (Entity)

Returns

Array of Gcloud::Datastore::Entity

Example

dataset.save task1, task2



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# File 'lib/gcloud/datastore/dataset.rb', line 136

def save *entities
  mutation = Proto.new_mutation
  save_entities_to_mutation entities, mutation
  response = connection.commit mutation
  auto_id_assign_ids response.mutation_result.insert_auto_id_key
  entities
end

#transaction ⇒ Object

Creates a Datastore Transaction.

Example

Runs the given block in a database transaction:

require "gcloud"

gcloud = Gcloud.new
dataset = gcloud.datastore

user = dataset.entity "User", "heidi" do |u|
  u["name"] = "Heidi Henderson"
  u["email"] = "[email protected]"
end

dataset.transaction do |tx|
  if tx.find(user.key).nil?
    tx.save user
  end
end

Alternatively, if no block is given a Transaction object is returned:

require "gcloud"

gcloud = Gcloud.new
dataset = gcloud.datastore

user = dataset.entity "User", "heidi" do |u|
  u["name"] = "Heidi Henderson"
  u["email"] = "[email protected]"
end

tx = dataset.transaction
begin
  if tx.find(user.key).nil?
    tx.save user
  end
  tx.commit
rescue
  tx.rollback
end



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# File 'lib/gcloud/datastore/dataset.rb', line 319

def transaction
  tx = Transaction.new connection
  return tx unless block_given?

  begin
    yield tx
    tx.commit
  rescue => e
    tx.rollback
    raise TransactionError.new("Transaction failed to commit.", e)
  end
end