Class: GraphQL::Relay::BaseConnection

Inherits:
Object
  • Object
show all
Defined in:
lib/graphql/relay/base_connection.rb

Overview

Subclasses must implement:

  • #cursor_from_node, which returns an opaque cursor for the given item
  • #sliced_nodes, which slices by before & after
  • #paged_nodes, which applies first & last limits

In a subclass, you have access to

Direct Known Subclasses

ArrayConnection, RelationConnection

Constant Summary collapse

CURSOR_SEPARATOR =

Just to encode data in the cursor, use something that won't conflict

"---"
CONNECTION_IMPLEMENTATIONS =

Map of collection class names -> connection_classes eg {"Array" => ArrayConnection}

{}
METHODS_FROM_ARGUMENTS =

Provide easy access to provided arguments:

[:first, :after, :last, :before]

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(nodes, arguments, field: nil, max_page_size: nil, parent: nil, context: nil) ⇒ BaseConnection

Make a connection, wrapping nodes

Parameters:

  • nodes (Object) —

    The collection of nodes

  • arguments (GraphQL::Query::Arguments) —

    Query arguments

  • field (GraphQL::Field) (defaults to: nil) —

    The underlying field

  • max_page_size (Int) (defaults to: nil) —

    The maximum number of results to return

  • parent (Object) (defaults to: nil) —

    The object which this collection belongs to

  • context (GraphQL::Query::Context) (defaults to: nil) —

    The context from the field being resolved



59
60
61
62
63
64
65
66
67
 
# File 'lib/graphql/relay/base_connection.rb', line 59

def initialize(nodes, arguments, field: nil, max_page_size: nil, parent: nil, context: nil)
  @nodes = nodes
  @arguments = arguments
  @max_page_size = max_page_size
  @field = field
  @parent = parent
  @context = context
  @encoder = context ? @context.schema.cursor_encoder : GraphQL::Schema::Base64Encoder
end

Instance Attribute Details

#arguments ⇒ Object (readonly)

Returns the value of attribute arguments.



50
51
52
 
# File 'lib/graphql/relay/base_connection.rb', line 50

def arguments
  @arguments
end

#field ⇒ Object (readonly)

Returns the value of attribute field.



50
51
52
 
# File 'lib/graphql/relay/base_connection.rb', line 50

def field
  @field
end

#max_page_size ⇒ Object (readonly)

Returns the value of attribute max_page_size.



50
51
52
 
# File 'lib/graphql/relay/base_connection.rb', line 50

def max_page_size
  @max_page_size
end

#nodes ⇒ Object (readonly)

Returns the value of attribute nodes.



50
51
52
 
# File 'lib/graphql/relay/base_connection.rb', line 50

def nodes
  @nodes
end

#parent ⇒ Object (readonly)

Returns the value of attribute parent.



50
51
52
 
# File 'lib/graphql/relay/base_connection.rb', line 50

def parent
  @parent
end

Class Method Details

.connection_for_nodes(nodes) ⇒ subclass of BaseConnection

Find a connection implementation suitable for exposing nodes

Parameters:

  • nodes (Object) —

    A collection of nodes (eg, Array, AR::Relation)

Returns:

  • (subclass of BaseConnection) —

    a connection Class for wrapping nodes



27
28
29
30
31
32
33
34
35
36
37
38
39
 
# File 'lib/graphql/relay/base_connection.rb', line 27

def connection_for_nodes(nodes)
  # Check for class _names_ because classes can be redefined in Rails development
  ancestor_names = nodes.class.ancestors.map(&:name)
  implementation_class_name = ancestor_names.find do |ancestor_class_name|
    CONNECTION_IMPLEMENTATIONS.include? ancestor_class_name
  end

  if implementation_class_name.nil?
    raise("No connection implementation to wrap #{nodes.class} (#{nodes})")
  else
    CONNECTION_IMPLEMENTATIONS[implementation_class_name]
  end
end

.register_connection_implementation(nodes_class, connection_class) ⇒ Object

Add connection_class as the connection wrapper for nodes_class eg, RelationConnection is the implementation for AR::Relation

Parameters:

  • nodes_class (Class) —

    A class representing a collection (eg, Array, AR::Relation)

  • connection_class (Class) —

    A class implementing Connection methods



45
46
47
 
# File 'lib/graphql/relay/base_connection.rb', line 45

def register_connection_implementation(nodes_class, connection_class)
  CONNECTION_IMPLEMENTATIONS[nodes_class.name] = connection_class
end

Instance Method Details

#after ⇒ Object

The value passed as after:, if there was one



88
89
90
91
92
 
# File 'lib/graphql/relay/base_connection.rb', line 88

METHODS_FROM_ARGUMENTS.each do |arg_name|
  define_method(arg_name) do
    arguments[arg_name]
  end
end

#before ⇒ Object

The value passed as before:, if there was one



88
89
90
91
92
 
# File 'lib/graphql/relay/base_connection.rb', line 88

METHODS_FROM_ARGUMENTS.each do |arg_name|
  define_method(arg_name) do
    arguments[arg_name]
  end
end

#cursor_from_node(object) ⇒ Object

An opaque operation which returns a connection-specific cursor.

Raises:

  • (NotImplementedError) 


134
135
136
 
# File 'lib/graphql/relay/base_connection.rb', line 134

def cursor_from_node(object)
  raise NotImplementedError, "must return a cursor for this object/connection pair"
end

#decode(data) ⇒ Object 



73
74
75
 
# File 'lib/graphql/relay/base_connection.rb', line 73

def decode(data)
  @encoder.decode(data, nonce: true)
end

#edge_nodes ⇒ Object

These are the nodes to render for this connection, probably wrapped by Edge



96
97
98
 
# File 'lib/graphql/relay/base_connection.rb', line 96

def edge_nodes
  @edge_nodes ||= paged_nodes
end

#encode(data) ⇒ Object 



69
70
71
 
# File 'lib/graphql/relay/base_connection.rb', line 69

def encode(data)
  @encoder.encode(data, nonce: true)
end

#end_cursor ⇒ Object

Used by pageInfo



125
126
127
128
129
130
131
 
# File 'lib/graphql/relay/base_connection.rb', line 125

def end_cursor
  if end_node = (respond_to?(:paged_nodes_array, true) ? paged_nodes_array : paged_nodes).last
    return cursor_from_node(end_node)
  else
    return nil
  end
end

#first ⇒ Object

The value passed as first:, if there was one



88
89
90
91
92
 
# File 'lib/graphql/relay/base_connection.rb', line 88

METHODS_FROM_ARGUMENTS.each do |arg_name|
  define_method(arg_name) do
    arguments[arg_name]
  end
end

#has_next_page ⇒ Object

Used by pageInfo



106
107
108
 
# File 'lib/graphql/relay/base_connection.rb', line 106

def has_next_page
  !!(first && sliced_nodes.count > first)
end

#has_previous_page ⇒ Object

Used by pageInfo



111
112
113
 
# File 'lib/graphql/relay/base_connection.rb', line 111

def has_previous_page
  !!(last && sliced_nodes.count > last)
end

#last ⇒ Object

The value passed as last:, if there was one



88
89
90
91
92
 
# File 'lib/graphql/relay/base_connection.rb', line 88

METHODS_FROM_ARGUMENTS.each do |arg_name|
  define_method(arg_name) do
    arguments[arg_name]
  end
end

#page_info ⇒ Object

Support the pageInfo field



101
102
103
 
# File 'lib/graphql/relay/base_connection.rb', line 101

def page_info
  self
end

#start_cursor ⇒ Object

Used by pageInfo



116
117
118
119
120
121
122
 
# File 'lib/graphql/relay/base_connection.rb', line 116

def start_cursor
  if start_node = (respond_to?(:paged_nodes_array, true) ? paged_nodes_array : paged_nodes).first
    return cursor_from_node(start_node)
  else
    return nil
  end
end