Class: ROM::Struct

Inherits:
Dry::Struct
  • Object
show all
Defined in:
lib/rom/struct.rb

Overview

Simple data-struct class

ROM structs are plain data structures loaded by repositories. They implement Hash protocol which means that they can be used in places where Hash-like objects are supported.

Repositories define subclasses of ROM::Struct automatically, they are not defined as constants in any module, instead, generated mappers are configured to use anonymous struct classes as models.

Structs are based on dry-struct gem, they include ‘schema` with detailed information about attribute types returned from relations, thus can be introspected to build additional functionality when desired.

Examples:

accessing relation struct model

rom = ROM.container(:sql, 'sqlite::memory') do |conf|
  conf.default.create_table(:users) do
    primary_key :id
    column :name, String
  end
end

class UserRepo < ROM::Repository[:users]
end

user_repo = UserRepo.new(rom)

# get auto-generated User struct
model = user_repo.users.mapper.model
# => ROM::Struct[User]

# see struct's schema attributes

# model.schema[:id]
# => #<Dry::Types::Constrained type=#<Dry::Types::Definition primitive=Integer options={}> options={:rule=>#<Dry::Logic::Rule::Predicate predicate=#<Method: Module(Dry::Logic::Predicates::Methods)#gt?> options={:args=>[0]}>, :meta=>{:primary_key=>true, :name=>:id, :source=>ROM::Relation::Name(users)}} rule=#<Dry::Logic::Rule::Predicate predicate=#<Method: Module(Dry::Logic::Predicates::Methods)#gt?> options={:args=>[0]}>>

model.schema[:name]
# => #<Dry::Types::Sum left=#<Dry::Types::Constrained type=#<Dry::Types::Definition primitive=NilClass options={}> options={:rule=>#<Dry::Logic::Rule::Predicate predicate=#<Method: Module(Dry::Logic::Predicates::Methods)#type?> options={:args=>[NilClass]}>} rule=#<Dry::Logic::Rule::Predicate predicate=#<Method: Module(Dry::Logic::Predicates::Methods)#type?> options={:args=>[NilClass]}>> right=#<Dry::Types::Definition primitive=String options={}> options={:meta=>{:name=>:name, :source=>ROM::Relation::Name(users)}}>

See Also:

Instance Method Summary collapse

Dynamic Method Handling

This class handles dynamic methods through the method_missing method

#method_missing(m, *args) ⇒ Object (private) 



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# File 'lib/rom/struct.rb', line 68

def method_missing(m, *args)
  inspected = inspect
  trace = caller

  # This is how MRI currently works
  # see func name_err_mesg_to_str in error.c
  name = inspected.size > 65 ? to_s : inspected

  raise NoMethodError.new("undefined method `#{ m }' for #{ name }", m, args).tap { |e| e.set_backtrace(trace) }
end

Instance Method Details

#fetch(name) ⇒ Object

Return attribute value

Parameters:

  • name (Symbol) —

    The attribute name



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# File 'lib/rom/struct.rb', line 62

def fetch(name)
  __send__(name)
end

#to_s ⇒ String

Returns a short string representation

Returns:

  • (String) 


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# File 'lib/rom/struct.rb', line 53

def to_s
  "#<#{self.class}:0x#{(object_id << 1).to_s(16)}>"
end