Represents a map stored in the database.

In postgres, for example, this represents binary encoded json

A builtin type that can be referenced via :map

• :fields (keyword/0) - The types of the fields in the map, and their constraints.
  If constraints are specified, only those fields will be in the casted map.
  For example:

  fields:  [
    amount: [
      type: :integer,
      constraints: [
        max: 10
      ]
    ],
    currency: [
      type: :string,
      allow_nil?: false,
      constraints: [
        max_length: 3
      ]
    ]
  ]  

  allow_nil? is true by default

  • :type (term/0) - Required.

  • :allow_nil? (boolean/0) - The default value is true.

  • :constraints (keyword/0) - The default value is [].