Class: GraphQL::Execution::Lazy Private

Inherits:
Object
  • Object
show all
Defined in:
lib/graphql/execution/lazy.rb,
lib/graphql/execution/lazy/lazy_method_map.rb

Overview

This class is part of a private API. You should avoid using this class if possible, as it may be removed or be changed in the future.

This wraps a value which is available, but not yet calculated, like a promise or future.

Calling #value will trigger calculation & return the "lazy" value.

This is an itty-bitty promise-like object, with key differences:

  • It has only two states, not-resolved and resolved
  • It has no error-catching functionality

Defined Under Namespace

Classes: LazyMethodMap

Constant Summary collapse

NullResult =

This constant is part of a private API. You should avoid using this constant if possible, as it may be removed or be changed in the future.

This can be used for fields which had no lazy results

Lazy.new(){}

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(field: nil, &get_value_func) ⇒ Lazy

This method is part of a private API. You should avoid using this method if possible, as it may be removed or be changed in the future.

Create a GraphQL::Execution::Lazy which will get its inner value by calling the block

Parameters:

  • field (GraphQL::Schema::Field) (defaults to: nil)
  • get_value_func (Proc) —

    a block to get the inner value (later)



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# File 'lib/graphql/execution/lazy.rb', line 20

def initialize(field: nil, &get_value_func)
  @get_value_func = get_value_func
  @resolved = false
  @field = field
end

Instance Attribute Details

#field ⇒ Object (readonly)

This method is part of a private API. You should avoid using this method if possible, as it may be removed or be changed in the future. 



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# File 'lib/graphql/execution/lazy.rb', line 15

def field
  @field
end

Class Method Details

.all(lazies) ⇒ Lazy

This method is part of a private API. You should avoid using this method if possible, as it may be removed or be changed in the future.

Returns A lazy which will sync all of lazies.

Parameters:

  • lazies (Array<Object>) —

    Maybe-lazy objects

Returns:

  • (Lazy) —

    A lazy which will sync all of lazies



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# File 'lib/graphql/execution/lazy.rb', line 57

def self.all(lazies)
  self.new {
    lazies.map { |l| l.is_a?(Lazy) ? l.value : l }
  }
end

Instance Method Details

#then ⇒ Lazy

This method is part of a private API. You should avoid using this method if possible, as it may be removed or be changed in the future.

Returns A GraphQL::Execution::Lazy whose value depends on another GraphQL::Execution::Lazy, plus any transformations in block.

Returns:



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# File 'lib/graphql/execution/lazy.rb', line 49

def then
  self.class.new {
    yield(value)
  }
end

#value ⇒ Object

This method is part of a private API. You should avoid using this method if possible, as it may be removed or be changed in the future.

Returns The wrapped value, calling the lazy block if necessary.

Returns:

  • (Object) —

    The wrapped value, calling the lazy block if necessary



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# File 'lib/graphql/execution/lazy.rb', line 27

def value
  if !@resolved
    @resolved = true
    v = @get_value_func.call
    if v.is_a?(Lazy)
      v = v.value
    end
    @value = v
  end

  # `SKIP` was made into a subclass of `GraphQL::Error` to improve runtime performance
  # (fewer clauses in a hot `case` block), but now it requires special handling here.
  # I think it's still worth it for the performance win, but if the number of special
  # cases grows, then maybe it's worth rethinking somehow.
  if @value.is_a?(StandardError) && @value != GraphQL::Execution::SKIP
    raise @value
  else
    @value
  end
end