Class: Neo4j::Wrapper::HasN::DeclRel

Inherits:
Object
  • Object
show all
Defined in:
lib/neo4j-wrapper/has_n/decl_rel.rb

Overview

A DSL for declared relationships has_n and has_one This DSL will be used to create accessor methods for relationships. Instead of using the ‘raw’ Neo4j::NodeMixin#rels method where one needs to know the name of relationship and direction one can use the generated accessor methods.

The DSL can also be used to specify a mapping to a Ruby class for a relationship, see Neo4j::HasN::DeclRelationshipDsl#relationship

The following methods will be generated:

Folder#files

returns an Enumerable of outgoing nodes for relationship ‘files’

Folder#files_rels

returns an Enumerable of outgoing relationships for relationship ‘files’

File#folder

for adding one node for the relationship ‘files’ from the outgoing Folder node

File#folder_rel

for accessing relationship ‘files’ from the outgoing Folder node

File#folder

for accessing nodes from relationship ‘files’ from the outgoing Folder node

Examples:


class Folder
   include Neo4j::NodeMixin
   property :name
   # Declaring a Many relationship to any other node
   has_n(:files)
 end

class File
  include Neo4j::NodeMixin
  # declaring a incoming relationship from Folder's relationship files
  has_one(:folder).from(Folder, :files)
end

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(method_id, has_one, source_class) ⇒ DeclRel

Returns a new instance of DeclRel.



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# File 'lib/neo4j-wrapper/has_n/decl_rel.rb', line 38

def initialize(method_id, has_one, source_class)
  @method_id = method_id
  @has_one = has_one
  @dir = :outgoing
  @rel_type = method_id.to_sym
  @source_class = source_class
end

Instance Attribute Details

#dir ⇒ Object (readonly)

Returns the value of attribute dir.



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# File 'lib/neo4j-wrapper/has_n/decl_rel.rb', line 36

def dir
  @dir
end

#rel_type ⇒ Object (readonly)

Returns the value of attribute rel_type.



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# File 'lib/neo4j-wrapper/has_n/decl_rel.rb', line 36

def rel_type
  @rel_type
end

#source_class ⇒ Object (readonly)

Returns the value of attribute source_class.



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# File 'lib/neo4j-wrapper/has_n/decl_rel.rb', line 36

def source_class
  @source_class
end

Instance Method Details

#_all_relationships(node) ⇒ Object 



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# File 'lib/neo4j-wrapper/has_n/decl_rel.rb', line 255

def _all_relationships(node) #:nodoc:
  node._rels(dir, rel_type)
end

#_each_node(node, &block) ⇒ Object 



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# File 'lib/neo4j-wrapper/has_n/decl_rel.rb', line 237

def _each_node(node, &block) #:nodoc:
  node._rels(dir, rel_type).each do |rel|
    block.call rel._other_node(node)
  end
end

#all_relationships(node) ⇒ Object 



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# File 'lib/neo4j-wrapper/has_n/decl_rel.rb', line 260

def all_relationships(node)
  node.rels(dir, rel_type)
end

#create_relationship_to(node, other) ⇒ Object 



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# File 'lib/neo4j-wrapper/has_n/decl_rel.rb', line 265

def create_relationship_to(node, other) # :nodoc:
  from, to = incoming? ? [other, node] : [node, other]

  if relationship_class
    relationship_class.new(@rel_type, from._java_node, to._java_node)
  else
    Neo4j::Relationship.new(@rel_type, from, to)
  end
end

#each_node(node, &block) ⇒ Object 



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# File 'lib/neo4j-wrapper/has_n/decl_rel.rb', line 230

def each_node(node, &block)
  node.rels(dir, rel_type).each do |rel|
    block.call(rel.other_node(node))
  end
end

#from(*args) ⇒ Object

Specifies an incoming relationship. Will use the outgoing relationship given by the from class.

Examples:

with prefix FileNode

class FolderNode
  include Neo4j::NodeMixin
  has_n(:files).to(FileNode)
end

class FileNode
  include Neo4j::NodeMixin
  # will only traverse any incoming relationship of type files from node FileNode
  has_one(:folder).from(FolderNode.files)
  # alternative: has_one(:folder).from(FolderNode, :files) 
end

file = FileNode.new
# create an outgoing relationship of type 'FileNode#files' from folder node to file (FileNode is the prefix).
file.folder = FolderNode.new

without prefix


class FolderNode
  include Neo4j::NodeMixin
  has_n(:files)
end

class FileNode
  include Neo4j::NodeMixin
  has_one(:folder).from(:files)  # will traverse any incoming relationship of type files
end

file = FileNode.new
# create an outgoing relationship of type 'files' from folder node to file
file.folder = FolderNode.new


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# File 'lib/neo4j-wrapper/has_n/decl_rel.rb', line 161

def from(*args)
  @dir = :incoming

  if args.size > 1
    # handle specified (prefixed) relationship, e.g. has_n(:known_by).from(clazz, :type)
    @target_name = args[0]
    @relationship_name = args[1].to_sym
    @rel_type = "#{@target_name}##{args[1]}".to_sym
  elsif Symbol === args[0]
    # handle unspecified (unprefixed) relationship, e.g. has_n(:known_by).from(:type)
    name = args[0].to_s
    if name.include?("#")
      @target_name, @relationship_name = name.split("#").map(&:to_sym)
    end
    @rel_type = args[0]
  else
    raise "Expected a symbol for, got #{args[0].inspect}"
  end
  self
end

#has_n? ⇒ true, false

Returns:

  • (true, false) 


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# File 'lib/neo4j-wrapper/has_n/decl_rel.rb', line 68

def has_n?
  !@has_one
end

#has_one? ⇒ true, false

Returns:

  • (true, false) 


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# File 'lib/neo4j-wrapper/has_n/decl_rel.rb', line 63

def has_one?
  @has_one
end

#incoming? ⇒ true, false

Returns:

  • (true, false) 


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# File 'lib/neo4j-wrapper/has_n/decl_rel.rb', line 73

def incoming? #:nodoc:
  @dir == :incoming
end

#inherit_new ⇒ Object 



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# File 'lib/neo4j-wrapper/has_n/decl_rel.rb', line 46

def inherit_new
  base = self
  dr = DeclRel.new(@method_id, @has_one, @source_class)
  dr.instance_eval do
    @dir = base.dir
    @rel_type = base.rel_type
    @target_name = base.target_name if base.target_name
    @source_class = base.source_class
  end
  dr
end

#relationship(rel_class) ⇒ Object

Specifies which relationship ruby class to use for the relationship

order = Order.new
order.products << Product.new
order.products_rels.first # => OrderLine

Examples:


class OrderLine
  include Neo4j::RelationshipMixin
  property :units
  property :unit_price
end

class Order
  property :total_cost
  property :dispatched
  has_n(:products).to(Product).relationship(OrderLine)                
  # strings can also be passed in, for cases where the class may not be initialized yet:
  # has_n(:products).to(Product).relationship('Order::Line')
end


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# File 'lib/neo4j-wrapper/has_n/decl_rel.rb', line 204

def relationship(rel_class)
  @relationship = rel_class
  self
end

#relationship_class ⇒ Object 



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# File 'lib/neo4j-wrapper/has_n/decl_rel.rb', line 215

def relationship_class # :nodoc:
  if @dir == :incoming
    other_class_dsl = target_class && target_class._decl_rels[@relationship_name]
    @relationship = other_class_dsl.relationship_class if other_class_dsl
  end
  @relationship = Neo4j::Wrapper.method(:to_class).call(@relationship) if @relationship.is_a? String
  @relationship
end

#single_node(node) ⇒ Object 



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# File 'lib/neo4j-wrapper/has_n/decl_rel.rb', line 244

def single_node(node)
  rel = single_relationship(node)
  rel && rel.other_node(node)
end

#single_relationship(node) ⇒ Object 



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# File 'lib/neo4j-wrapper/has_n/decl_rel.rb', line 250

def single_relationship(node) #:nodoc:
  node.rel(dir, rel_type)
end

#target_class ⇒ Object 



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# File 'lib/neo4j-wrapper/has_n/decl_rel.rb', line 224

def target_class
  @target_name && (@target_name.is_a?(Class) ? @target_name : Neo4j::Wrapper.to_class(@target_name.to_s))
end

#target_name ⇒ Object 



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# File 'lib/neo4j-wrapper/has_n/decl_rel.rb', line 210

def target_name
  @target_name
end

#to(target, rel_type = @method_id) ⇒ Object

Declares an outgoing relationship type. It is possible to prefix relationship types so that it’s possible to distinguish different incoming relationships. There is no validation that the added node is of the specified class.

folder = FolderNode.new
# generate a relationship between folder and file of type 'FileNode#files'
folder.files << FileNode.new

Examples:

Example

class FolderNode
  include Neo4j::NodeMixin
  has_n(:files).to(FileNode)
  has_one(:root).to("FileSystem") # also possible, if the class is not defined yet
end

without prefix


class FolderNode
  include Neo4j::NodeMixin
  has_n(:files).to(:contains)
end

file = FileNode.new
# create an outgoing relationship of type 'contains' from folder node to file
folder.files << FolderNode.new

Parameters:

  • target (Class, String, Symbol) —

    the other class to which this relationship goes (if String or Class) or the relationship (if Symbol)

  • rel_type (Class, String, Symbol) (defaults to: @method_id) —

    the rel_type postfix for the relationships, which defaults to the same as the has_n/one method id

Returns:

  • self



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# File 'lib/neo4j-wrapper/has_n/decl_rel.rb', line 107

def to(target, rel_type = @method_id)
  @dir = :outgoing

  if Class === target || String === target
    # handle e.g. has_n(:friends).to(class)
    @target_name = target
    @rel_type = "#{@source_class}##{rel_type}".to_sym
  elsif Symbol === target
    # handle e.g. has_n(:friends).to(:knows) or to("Person#friends")
    @target_name = target.to_s.split("#")[0] if target.to_s.include?("#")
    @rel_type = target.to_sym
  else
    raise "Expected a class or a symbol for, got #{target}/#{target.class}"
  end
  self
end

#to_s ⇒ Object 



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# File 'lib/neo4j-wrapper/has_n/decl_rel.rb', line 58

def to_s
  "DeclRel #{object_id} dir: #{@dir} rel_id: #{@method_id}, rel_type: #{@rel_type}, target_class:#{@target_name} rel_class:#{@relationship}"
end