Hash Records

The :hash_access attribute option reads values from Hash keys, for records loaded as Hashes from JSON, Redis or raw SQL.

class UserSerializer < Serega
  attribute :name, hash_access: true        # record[:name]
  attribute :email, hash_access: :string    # record["email"]
  attribute :full_name, method: :name, hash_access: true # record[:name]
end

UserSerializer.to_h({:name => "Bruce", "email" => "bruce@wayne.com"})
# => {name: "Bruce", email: "bruce@wayne.com", full_name: "Bruce"}

Modes:

• :symbol reads record[:name];

• :string reads record["name"];

• true uses config.hash_access.default_mode, :symbol by default.

Records can be any objects with #[], #fetch and #key?.

Missing keys

A missing key raises KeyError. allow_missing_key: true serializes nil instead:

attribute :age, hash_access: true
# => KeyError: key not found: :age

attribute :age, hash_access: {allow_missing_key: true}
attribute :age, hash_access: {mode: :string, allow_missing_key: true}
# => {age: nil}

Defaults

class AppSerializer < Serega
  config.hash_access.default_mode = :string           # mode of `hash_access: true`
  config.hash_access.default_allow_missing_key = true # nil for missing keys
end

Delegates

Delegates choose hash access per step: :to_hash_access reads the associated record, :hash_access reads the final value. Both accept the same values as the :hash_access attribute option.

attribute :city, delegate: {to: :address, to_hash_access: true}                    # record[:address].city
attribute :city, delegate: {to: :address, hash_access: true}                       # record.address[:city]
attribute :city, delegate: {to: :address, to_hash_access: true, hash_access: true} # record[:address][:city]

# record["address"][:city], nil when record has no "address"
attribute :city, delegate: {
  to: :address,
  allow_nil: true,
  to_hash_access: {mode: :string, allow_missing_key: true},
  hash_access: :symbol
}

The :hash_access attribute option can not be combined with :delegate.

Relations

class AddressSerializer < Serega
  attribute :city, hash_access: true
end

class UserSerializer < Serega
  attribute :address, hash_access: true, serializer: AddressSerializer
end

UserSerializer.to_h({address: {city: "Gotham"}}) # => {address: {city: "Gotham"}}