This is the output of calling inspect on a datamapper many_to_many relationship object for the following scenario:
Person.has(n, :projects, :through => :project_memberships)
Below is inspect's output for the :projects relationship
#<DataMapper::Associations::ManyToMany::Relationship:0x1625330
@name=:projects,
@instance_variable_name="@projects",
@min=0
@max=Infinity,
@parent_repository_name=:default,
@parent_model=Person,
@parent_properties=nil,
@child_repository_name=:default,
@child_model=Project,
@child_model_name="Project",
@child_key=[#<DataMapper::Property @model=Project @name=:id>],
@child_properties=nil,
@constraint=:protect,
@query={},
@links=[
#<DataMapper::Associations::OneToMany::Relationship:0x16270f4
@name=:project_memberships,
@instance_variable_name="@project_memberships",
@min=0
@max=Infinity,
@parent_repository_name=:default,
@parent_model=Person,
@parent_key=[#<DataMapper::Property @model=Person @name=:id>],
@parent_properties=nil,
@child_repository_name=:default,
@child_model=ProjectMembership,
@child_model_name="ProjectMembership",
@child_properties=nil,
@child_key=[#<DataMapper::Property @model=ProjectMembership @name=:person_id>],
@query={},
@constraint=:destroy,
@options={ :parent_repository_name=>:default, :constraint=>:destroy, :min=>0, :max=>Infinity, :child_repository_name=>nil },
@inverse=#<DataMapper::Associations::ManyToOne::Relationship:0x15ef654
@name=:person,
@instance_variable_name="@person",
@min=1,
@max=1,
@parent_repository_name=:default,
@parent_model=Person,
@parent_model_name="Person"
@parent_properties=nil,
@parent_key=[#<DataMapper::Property @model=Person @name=:id>],
@child_repository_name=:default,
@child_model=ProjectMembership,
@child_properties=nil,
@child_key=[#<DataMapper::Property @model=ProjectMembership @name=:person_id>],
@query={},
@nullable=false,
@options={:parent_repository_name=>nil, :min=>1, :max=>1, :child_repository_name=>:default},
@inverse=#<DataMapper::Associations::OneToMany::Relationship:0x16270f4 ...>,
>
>,
#<DataMapper::Associations::ManyToOne::Relationship:0x15edae8
@name=:project,
@instance_variable_name="@project",
@min=1,
@max=1,
@parent_repository_name=:default,
@parent_model=Project,
@parent_model_name="Project"
@parent_properties=nil,
@parent_key=[#<DataMapper::Property @model=Project @name=:id>],
@child_repository_name=:default,
@child_model=ProjectMembership,
@child_properties=nil,
@child_key=[#<DataMapper::Property @model=ProjectMembership @name=:project_id>],
@query={},
@nullable=false,
@options={:parent_repository_name=>nil, :min=>1, :max=>1, :child_repository_name=>:default},
@inverse=#<DataMapper::Associations::OneToMany::Relationship:0x16027cc
@name=:project_memberships,
@instance_variable_name="@project_memberships",
@min=0
@max=Infinity,
@parent_repository_name=:default,
@parent_model=Project,
@parent_properties=nil,
@parent_key=[#<DataMapper::Property @model=Project @name=:id>],
@child_repository_name=:default,
@child_model=ProjectMembership,
@child_model_name="ProjectMembership",
@child_properties=nil,
@child_key=[#<DataMapper::Property @model=ProjectMembership @name=:project_id>],
@query={},
@constraint=:destroy,
@options={:parent_repository_name=>:default, :constraint=>:destroy, :min=>0, :max=>Infinity, :child_repository_name=>nil},
>
>
],
@options={
:min=>0,
:max=>Infinity,
:parent_repository_name=>:default,
:child_repository_name=>nil,
:through=>#<DataMapper::Associations::OneToMany::Relationship:0x16270f4
@name=:project_memberships,
@instance_variable_name="@project_memberships",
@min=0
@max=Infinity,
@parent_repository_name=:default,
@parent_model=Person,
@parent_properties=nil,
@parent_key=[#<DataMapper::Property @model=Person @name=:id>],
@child_repository_name=:default,
@child_model=ProjectMembership,
@child_model_name="ProjectMembership",
@child_properties=nil,
@child_key=[#<DataMapper::Property @model=ProjectMembership @name=:person_id>],
@constraint=:destroy,
@query={},
@options={:parent_repository_name=>:default, :constraint=>:destroy, :min=>0, :max=>Infinity, :child_repository_name=>nil},
@inverse=#<DataMapper::Associations::ManyToOne::Relationship:0x15ef654
@name=:person,
@instance_variable_name="@person",
@min=1,
@max=1,
@parent_repository_name=:default,
@parent_model=Person,
@parent_model_name="Person"
@parent_properties=nil,
@parent_key=[#<DataMapper::Property @model=Person @name=:id>],
@child_repository_name=:default,
@child_model=ProjectMembership,
@child_properties=nil,
@child_key=[#<DataMapper::Property @model=ProjectMembership @name=:person_id>],
@nullable=false,
@query={},
@options={:parent_repository_name=>nil, :min=>1, :max=>1, :child_repository_name=>:default},
@inverse=#<DataMapper::Associations::OneToMany::Relationship:0x16270f4 ...>,
>
>
},
@through=#<DataMapper::Associations::OneToMany::Relationship:0x16270f4
@name=:project_memberships,
@instance_variable_name="@project_memberships",
@min=0
@max=Infinity,
@parent_repository_name=:default,
@parent_model=Person,
@parent_properties=nil,
@parent_key=[#<DataMapper::Property @model=Person @name=:id>],
@child_repository_name=:default,
@child_model=ProjectMembership,
@child_model_name="ProjectMembership",
@child_properties=nil,
@child_key=[#<DataMapper::Property @model=ProjectMembership @name=:person_id>],
@constraint=:destroy,
@query={},
@options={:parent_repository_name=>:default, :constraint=>:destroy, :min=>0, :max=>Infinity, :child_repository_name=>nil},
@inverse=#<DataMapper::Associations::ManyToOne::Relationship:0x15ef654
@name=:person,
@instance_variable_name="@person",
@min=1,
@max=1,
@parent_repository_name=:default,
@parent_model=Person,
@parent_model_name="Person"
@parent_properties=nil,
@parent_key=[#<DataMapper::Property @model=Person @name=:id>],
@child_repository_name=:default,
@child_model=ProjectMembership,
@child_properties=nil,
@child_key=[#<DataMapper::Property @model=ProjectMembership @name=:person_id>],
@nullable=false,
@query={},
@options={:parent_repository_name=>nil, :min=>1, :max=>1, :child_repository_name=>:default},
@inverse=#<DataMapper::Associations::OneToMany::Relationship:0x16270f4 ...>,
>
>,
@many_to_many_query={
:links=>[
#<DataMapper::Associations::OneToMany::Relationship:0x16270f4
@name=:project_memberships,
@instance_variable_name="@project_memberships",
@min=0
@max=Infinity,
@parent_repository_name=:default,
@parent_model=Person,
@parent_properties=nil,
@parent_key=[#<DataMapper::Property @model=Person @name=:id>],
@child_repository_name=:default,
@child_model=ProjectMembership,
@child_model_name="ProjectMembership",
@child_properties=nil,
@child_key=[#<DataMapper::Property @model=ProjectMembership @name=:person_id>],
@constraint=:destroy,
@query={},
@options={:parent_repository_name=>:default, :constraint=>:destroy, :min=>0, :max=>Infinity, :child_repository_name=>nil},
@inverse=#<DataMapper::Associations::ManyToOne::Relationship:0x15ef654
@name=:person,
@instance_variable_name="@person",
@min=1,
@max=1,
@parent_repository_name=:default,
@parent_model=Person,
@parent_model_name="Person"
@parent_properties=nil,
@parent_key=[#<DataMapper::Property @model=Person @name=:id>],
@child_repository_name=:default,
@child_model=ProjectMembership,
@child_properties=nil,
@child_key=[#<DataMapper::Property @model=ProjectMembership @name=:person_id>],
@nullable=false,
@query={},
@options={:parent_repository_name=>nil, :min=>1, :max=>1, :child_repository_name=>:default},
@inverse=#<DataMapper::Associations::OneToMany::Relationship:0x16270f4 ...>,
>
>,
#<DataMapper::Associations::ManyToOne::Relationship:0x15edae8
@name=:project,
@instance_variable_name="@project",
@min=1,
@max=1,
@parent_repository_name=:default,
@parent_model=Project,
@parent_model_name="Project"
@parent_properties=nil,
@parent_key=[#<DataMapper::Property @model=Project @name=:id>],
@child_repository_name=:default,
@child_model=ProjectMembership,
@child_properties=nil,
@child_key=[#<DataMapper::Property @model=ProjectMembership @name=:project_id>],
@nullable=false,
@query={},
@options={:parent_repository_name=>nil, :min=>1, :max=>1, :child_repository_name=>:default},
@inverse=#<DataMapper::Associations::OneToMany::Relationship:0x16027cc
@name=:project_memberships,
@instance_variable_name="@project_memberships",
@min=0
@max=Infinity,
@parent_repository_name=:default,
@parent_model=Project,
@parent_properties=nil,
@parent_key=[#<DataMapper::Property @model=Project @name=:id>],
@child_repository_name=:default,
@child_model=ProjectMembership,
@child_model_name="ProjectMembership",
@child_properties=nil,
@child_key=[#<DataMapper::Property @model=ProjectMembership @name=:project_id>],
@constraint=:destroy,
@query={},
@options={:parent_repository_name=>:default, :constraint=>:destroy, :min=>0, :max=>Infinity, :child_repository_name=>nil},
>
>
]
}
>
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