class ActiveGraph::Node::Query::QueryProxy

rubocop:disable Metrics/ClassLength

Constants

METHODS

Attributes

association[R]

The most recent node to start a QueryProxy chain. Will be nil when using QueryProxy chains on class methods.

context[RW]
model[R]

The most recent node to start a QueryProxy chain. Will be nil when using QueryProxy chains on class methods.

node_var[R]

The current node identifier on deck, so to speak. It is the object that will be returned by calling `each` and the last node link in the QueryProxy chain.

query_proxy[R]
rel_var[R]

The relationship identifier most recently used by the QueryProxy chain.

source_object[R]

The most recent node to start a QueryProxy chain. Will be nil when using QueryProxy chains on class methods.

start_object[R]
starting_query[R]

The most recent node to start a QueryProxy chain. Will be nil when using QueryProxy chains on class methods.

Public Class Methods

new(model, association = nil, options = {}) click to toggle source

QueryProxy is Node's Cypher DSL. While the name might imply that it creates queries in a general sense, it is actually referring to ActiveGraph::Core::Query, which is a pure Ruby Cypher DSL provided by the activegraph gem. QueryProxy provides ActiveRecord-like methods for common patterns. When it's not handling CRUD for relationships and queries, it provides Node's association chaining (`student.lessons.teachers.where(age: 30).hobbies`) and enjoys long walks on the beach.

It should not ever be necessary to instantiate a new QueryProxy object directly, it always happens as a result of calling a method that makes use of it.

@param [Constant] model The class which included Node (typically a model, hence the name) from which the query originated. @param [ActiveGraph::Node::HasN::Association] association The Node association (an object created by a has_one or has_many) that created this object. @param [Hash] options Additional options pertaining to the QueryProxy object. These may include: @option options [String, Symbol] :node_var A string or symbol to be used by Cypher within its query string as an identifier @option options [String, Symbol] :rel_var Same as above but pertaining to a relationship identifier @option options [Range, Integer, Symbol, Hash] :rel_length A Range, a Integer, a Hash or a Symbol to indicate the variable-length/fixed-length

qualifier of the relationship. See http://neo4jrb.readthedocs.org/en/latest/Querying.html#variable-length-relationships.

@option options [ActiveGraph::Node] :source_object The node instance at the start of the QueryProxy chain @option options [QueryProxy] :query_proxy An existing QueryProxy chain upon which this new object should be built

QueryProxy objects are evaluated lazily.

   # File lib/active_graph/node/query/query_proxy.rb
40 def initialize(model, association = nil, options = {})
41   @model = model
42   @association = association
43   @context = options.delete(:context)
44   @options = options
45   @associations_spec = []
46 
47   instance_vars_from_options!(options)
48 
49   @match_type = @optional ? :optional_match : :match
50 
51   @rel_var = options[:rel] || _rel_chain_var
52 
53   @chain = []
54   @params = @query_proxy ? @query_proxy.instance_variable_get('@params') : {}
55 end

Public Instance Methods

<<(other_node) click to toggle source

To add a relationship for the node for the association on this QueryProxy

    # File lib/active_graph/node/query/query_proxy.rb
171 def <<(other_node)
172   _create_relation_or_defer(other_node)
173   self
174 end
[](index) click to toggle source
    # File lib/active_graph/node/query/query_proxy.rb
197 def [](index)
198   # TODO: Maybe for this and other methods, use array if already loaded, otherwise
199   # use OFFSET and LIMIT 1?
200   self.to_a[index]
201 end
_create_relationship(other_node_or_nodes, properties) click to toggle source
    # File lib/active_graph/node/query/query_proxy.rb
234 def _create_relationship(other_node_or_nodes, properties)
235   association._create_relationship(@start_object, other_node_or_nodes, properties)
236 end
_model_label_string(with_labels = true) click to toggle source

param [TrueClass, FalseClass] with_labels This param is used by certain QueryProxy methods that already have the neo_id and therefore do not need labels. The @association_labels instance var is set during init and used during association chaining to keep labels out of Cypher queries.

    # File lib/active_graph/node/query/query_proxy.rb
122 def _model_label_string(with_labels = true)
123   return if !@model || (!with_labels || @association_labels == false)
124   @model.mapped_label_names.map { |label_name| ":`#{label_name}`" }.join
125 end
_nodeify!(*args) click to toggle source
    # File lib/active_graph/node/query/query_proxy.rb
222 def _nodeify!(*args)
223   other_nodes = [args].flatten!.map! do |arg|
224     (arg.is_a?(Integer) || arg.is_a?(String)) ? @model.find_by(id: arg) : arg
225   end.compact
226 
227   if @model && other_nodes.any? { |other_node| !other_node.class.mapped_label_names.include?(@model.mapped_label_name) }
228     fail ArgumentError, "Node must be of the association's class when model is specified"
229   end
230 
231   other_nodes
232 end
base_query(var, with_labels = true) click to toggle source
    # File lib/active_graph/node/query/query_proxy.rb
109 def base_query(var, with_labels = true)
110   if @association
111     chain_var = _association_chain_var
112     (_association_query_start(chain_var) & _query).break.send(@match_type,
113                                                               "(#{chain_var})#{_association_arrow}(#{var}#{_model_label_string})")
114   else
115     starting_query ? starting_query : _query_model_as(var, with_labels)
116   end
117 end
branch(&block) click to toggle source

Executes the relation chain specified in the block, while keeping the current scope

@example Load all people that have friends

Person.all.branch { friends }.to_a # => Returns a list of `Person`

@example Load all people that has old friends

Person.all.branch { friends.where('age > 70') }.to_a # => Returns a list of `Person`

@yield the block that will be evaluated starting from the current scope

@return [QueryProxy] A new QueryProxy

    # File lib/active_graph/node/query/query_proxy.rb
187 def branch(&block)
188   fail LocalJumpError, 'no block given' if block.nil?
189   # `as(identity)` is here to make sure we get the right variable
190   # There might be a deeper problem of the variable changing when we
191   # traverse an association
192   as(identity).instance_eval(&block).query.proxy_as(self.model, identity).tap do |new_query_proxy|
193     propagate_context(new_query_proxy)
194   end
195 end
create(other_nodes, properties = {}) click to toggle source
    # File lib/active_graph/node/query/query_proxy.rb
203 def create(other_nodes, properties = {})
204   fail 'Can only create relationships on associations' if !@association
205   other_nodes = _nodeify!(*other_nodes)
206 
207   ActiveGraph::Base.transaction do
208     other_nodes.each do |other_node|
209       if other_node.neo_id
210         other_node.try(:delete_reverse_has_one_core_rel, association)
211       else
212         other_node.save
213       end
214 
215       @start_object.association_proxy_cache.clear
216 
217       _create_relationship(other_node, properties)
218     end
219   end
220 end
identity() click to toggle source
   # File lib/active_graph/node/query/query_proxy.rb
67 def identity
68   @node_var || _result_string(_chain_level + 1)
69 end
Also aliased as: node_identity
inspect() click to toggle source
   # File lib/active_graph/node/query/query_proxy.rb
57 def inspect
58   formatted_nodes = ActiveGraph::Node::NodeListFormatter.new(to_a)
59   "#<QueryProxy #{@context} #{formatted_nodes.inspect}>"
60 end
method_missing(method_name, *args, &block) click to toggle source

QueryProxy objects act as a representation of a model at the class level so we pass through calls This allows us to define class functions for reusable query chaining or for end-of-query aggregation/summarizing

Calls superclass method
    # File lib/active_graph/node/query/query_proxy.rb
246 def method_missing(method_name, *args, &block)
247   if @model && @model.respond_to?(method_name)
248     scoping { @model.public_send(method_name, *args, &block) }
249   else
250     super
251   end
252 end
node_identity()
Alias for: identity
optional?() click to toggle source
    # File lib/active_graph/node/query/query_proxy.rb
258 def optional?
259   @optional == true
260 end
params(params) click to toggle source
   # File lib/active_graph/node/query/query_proxy.rb
80 def params(params)
81   new_link.tap { |new_query| new_query._add_params(params) }
82 end
query() click to toggle source

Like calling query_as, but for when you don't care about the variable name

   # File lib/active_graph/node/query/query_proxy.rb
85 def query
86   query_as(identity)
87 end
query_as(var, with_labels = true) click to toggle source

Build a ActiveGraph::Core::Query object for the QueryProxy. This is necessary when you want to take an existing QueryProxy chain and work with it from the more powerful (but less friendly) ActiveGraph::Core::Query. @param [String,Symbol] var The identifier to use for node at this link of the QueryProxy chain.

.. code-block

ruby

student.lessons.query_as(:l).with('your cypher here...')
   # File lib/active_graph/node/query/query_proxy.rb
96 def query_as(var, with_labels = true)
97   query_from_chain(chain, base_query(var, with_labels).params(@params), var)
98     .tap { |query| query.proxy_chain_level = _chain_level }
99 end
query_from_chain(chain, base_query, var) click to toggle source
    # File lib/active_graph/node/query/query_proxy.rb
101 def query_from_chain(chain, base_query, var)
102   chain.inject(base_query) do |query, link|
103     args = link.args(var, rel_var)
104 
105     args.is_a?(Array) ? query.send(link.clause, *args) : query.send(link.clause, args)
106   end
107 end
read_attribute_for_serialization(*args) click to toggle source
    # File lib/active_graph/node/query/query_proxy.rb
238 def read_attribute_for_serialization(*args)
239   to_a.map { |o| o.read_attribute_for_serialization(*args) }
240 end
rel_identity() click to toggle source
   # File lib/active_graph/node/query/query_proxy.rb
74 def rel_identity
75   ActiveSupport::Deprecation.warn 'rel_identity is deprecated and may be removed from future releases, use rel_var instead.', caller
76 
77   @rel_var
78 end
respond_to_missing?(method_name, include_all = false) click to toggle source
Calls superclass method
    # File lib/active_graph/node/query/query_proxy.rb
254 def respond_to_missing?(method_name, include_all = false)
255   (@model && @model.respond_to?(method_name, include_all)) || super
256 end
scoping() { || ... } click to toggle source

Scope all queries to the current scope.

.. code-block

ruby

Comment.where(post_id: 1).scoping do
  Comment.first
end

TODO: unscoped Please check unscoped if you want to remove all previous scopes (including the default_scope) during the execution of a block.

    # File lib/active_graph/node/query/query_proxy.rb
138 def scoping
139   previous = @model.current_scope
140   @model.current_scope = self
141   yield
142 ensure
143   @model.current_scope = previous
144 end
to_cypher_with_params(columns = [self.identity]) click to toggle source

Returns a string of the cypher query with return objects and params @param [Array] columns array containing symbols of identifiers used in the query @return [String]

    # File lib/active_graph/node/query/query_proxy.rb
165 def to_cypher_with_params(columns = [self.identity])
166   final_query = query.return_query(columns)
167   "#{final_query.to_cypher} | params: #{final_query.send(:merge_params)}"
168 end
unpersisted_start_object?() click to toggle source
    # File lib/active_graph/node/query/query_proxy.rb
271 def unpersisted_start_object?
272   @start_object && @start_object.new_record?
273 end

Protected Instance Methods

_add_params(params) click to toggle source

Methods are underscored to prevent conflict with user class methods

    # File lib/active_graph/node/query/query_proxy.rb
288 def _add_params(params)
289   @params = @params.merge(params)
290 end
_association_arrow(properties = {}, create = false) click to toggle source
    # File lib/active_graph/node/query/query_proxy.rb
319 def _association_arrow(properties = {}, create = false)
320   @association && @association.arrow_cypher(@rel_var, properties, create, false, @rel_length)
321 end
_association_chain_var() click to toggle source
    # File lib/active_graph/node/query/query_proxy.rb
327 def _association_chain_var
328   fail 'Crazy error' if !(start_object || @query_proxy)
329 
330   if start_object
331     :"#{start_object.class.name.gsub('::', '_').downcase}#{start_object.neo_id}"
332   else
333     @query_proxy.node_var || :"node#{_chain_level}"
334   end
335 end
_association_query_start(var) click to toggle source
    # File lib/active_graph/node/query/query_proxy.rb
337 def _association_query_start(var)
338   # TODO: Better error
339   fail 'Crazy error' if !(object = (start_object || @query_proxy))
340 
341   object.query_as(var)
342 end
_chain_level() click to toggle source
    # File lib/active_graph/node/query/query_proxy.rb
323 def _chain_level
324   (@query_proxy ? @query_proxy._chain_level : (@chain_level || 0)) + 1
325 end
_create_relation_or_defer(other_node) click to toggle source
    # File lib/active_graph/node/query/query_proxy.rb
277 def _create_relation_or_defer(other_node)
278   if @start_object._persisted_obj
279     create(other_node, {})
280   elsif @association
281     @start_object.defer_create(@association.name, other_node)
282   else
283     fail 'Another crazy error!'
284   end
285 end
_match_arg(var, with_labels) click to toggle source

@param [String, Symbol] var The Cypher identifier to use within the match string @param [Boolean] with_labels Send “true” to include model labels where possible.

    # File lib/active_graph/node/query/query_proxy.rb
302 def _match_arg(var, with_labels)
303   if @model && with_labels != false
304     labels = @model.respond_to?(:mapped_label_names) ? _model_label_string : @model
305     {var.to_sym => labels}
306   else
307     var.to_sym
308   end
309 end
_query() click to toggle source
    # File lib/active_graph/node/query/query_proxy.rb
311 def _query
312   ActiveGraph::Base.new_query(context: @context)
313 end
_query_model_as(var, with_labels = true) click to toggle source
    # File lib/active_graph/node/query/query_proxy.rb
296 def _query_model_as(var, with_labels = true)
297   _query.break.send(@match_type, _match_arg(var, with_labels))
298 end
_rel_chain_var() click to toggle source
    # File lib/active_graph/node/query/query_proxy.rb
344 def _rel_chain_var
345   :"rel#{_chain_level - 1}"
346 end
_result_string(index = nil) click to toggle source
    # File lib/active_graph/node/query/query_proxy.rb
315 def _result_string(index = nil)
316   "result_#{(association || model).try(:name)}#{index}".downcase.tr(':', '').to_sym
317 end

Private Instance Methods

build_deeper_query_proxy(method, args) click to toggle source
    # File lib/active_graph/node/query/query_proxy.rb
359 def build_deeper_query_proxy(method, args)
360   new_link.tap do |new_query_proxy|
361     Link.for_args(@model, method, args, association).each { |link| new_query_proxy._add_links(link) }
362   end
363 end
instance_vars_from_options!(options) click to toggle source
    # File lib/active_graph/node/query/query_proxy.rb
352 def instance_vars_from_options!(options)
353   @node_var, @source_object, @starting_query, @optional,
354       @start_object, @query_proxy, @chain_level, @association_labels,
355       @rel_length = options.values_at(:node, :source_object, :starting_query, :optional,
356                                       :start_object, :query_proxy, :chain_level, :association_labels, :rel_length)
357 end