View Source Ecto.Enum (Ecto v3.12.2)
A custom type that maps atoms to strings or integers.
Ecto.Enum
must be used whenever you want to keep atom values in a field.
Since atoms cannot be persisted to the database, Ecto.Enum
converts them
to strings or integers when writing to the database and converts them back
to atoms when loading data. It can be used in your schemas as follows:
# Stored as strings
field :status, Ecto.Enum, values: [:foo, :bar, :baz]
or
# Stored as integers
field :status, Ecto.Enum, values: [foo: 1, bar: 2, baz: 5]
Therefore, the type to be used in your migrations for enum fields depends on the choice above. For the cases above, one would do, respectively:
add :status, :string
or
add :status, :integer
Some databases also support enum types, which you could use in combination with the above.
Composite types, such as :array
, are also supported which allow selecting
multiple values per record:
field :roles, {:array, Ecto.Enum}, values: [:author, :editor, :admin]
Overall, :values
must be a list of atoms or a keyword list. Values will be
cast to atoms safely and only if the atom exists in the list (otherwise an
error will be raised). Attempting to load any string/integer not represented
by an atom in the list will be invalid.
The helper function mappings/2
returns the mappings for a given schema and
field, which can be used in places like form drop-downs. See mappings/2
for
examples.
If you want the values only, you can use values/2
, and if you want
the "dump-able" values only, you can use dump_values/2
.
Embeds
Ecto.Enum
allows to customize how fields are dumped within embeds through the
:embed_as
option. Two alternatives are supported: :values
, which will save
the enum keys (and not their respective mapping), and :dumped
, which will save
the dumped value. The default is :values
. For example, assuming the following
schema:
defmodule EnumSchema do
use Ecto.Schema
schema "my_schema" do
embeds_one :embed, Embed do
field :embed_as_values, Ecto.Enum, values: [foo: 1, bar: 2], embed_as: :values
field :embed_as_dump, Ecto.Enum, values: [foo: 1, bar: 2], embed_as: :dumped
end
end
end
The :embed_as_values
field value will save :foo
or :bar
, while the
:embed_as_dump
field value will save 1
or 2
.
Summary
Functions
Returns the possible dump values for a given schema or types map and field
Returns the mappings between values and dumped values.
Returns the possible values for a given schema or types map and field.
Functions
Returns the possible dump values for a given schema or types map and field
"Dump values" are the values that can be dumped in the database. For enums stored as strings, these are the strings that will be dumped in the database. For enums stored as integers, these are the integers that will be dumped in the database.
Examples
Assuming this schema:
defmodule MySchema do
use Ecto.Schema
schema "my_schema" do
field :my_string_enum, Ecto.Enum, values: [:foo, :bar, :baz]
field :my_integer_enum, Ecto.Enum, values: [foo: 1, bar: 2, baz: 5]
end
end
Then:
Ecto.Enum.dump_values(MySchema, :my_string_enum)
#=> ["foo", "bar", "baz"]
Ecto.Enum.dump_values(MySchema, :my_integer_enum)
#=> [1, 2, 5]
schema_or_types
can also be a types map. See mappings/2
for more information.
Returns the mappings between values and dumped values.
Examples
Assuming this schema:
defmodule MySchema do
use Ecto.Schema
schema "my_schema" do
field :my_string_enum, Ecto.Enum, values: [:foo, :bar, :baz]
field :my_integer_enum, Ecto.Enum, values: [foo: 1, bar: 2, baz: 5]
end
end
Here are some examples of using mappings/2
with it:
Ecto.Enum.mappings(MySchema, :my_string_enum)
#=> [foo: "foo", bar: "bar", baz: "baz"]
Ecto.Enum.mappings(MySchema, :my_integer_enum)
#=> [foo: 1, bar: 2, baz: 5]
Examples of calling mappings/2
with a types map:
schemaless_types = %{
my_enum: Ecto.ParameterizedType.init(Ecto.Enum, values: [:foo, :bar, :baz]),
my_integer_enum: Ecto.ParameterizedType.init(Ecto.Enum, values: [foo: 1, bar: 2, baz: 5])
}
Ecto.Enum.mappings(schemaless_types, :my_enum)
#=> [foo: "foo", bar: "bar", baz: "baz"]
Ecto.Enum.mappings(schemaless_types, :my_integer_enum)
#=> [foo: 1, bar: 2, baz: 5]
Returns the possible values for a given schema or types map and field.
These values are the atoms that represent the different possible values of the field.
Examples
Assuming this schema:
defmodule MySchema do
use Ecto.Schema
schema "my_schema" do
field :my_string_enum, Ecto.Enum, values: [:foo, :bar, :baz]
field :my_integer_enum, Ecto.Enum, values: [foo: 1, bar: 2, baz: 5]
end
end
Then:
Ecto.Enum.values(MySchema, :my_string_enum)
#=> [:foo, :bar, :baz]
Ecto.Enum.values(MySchema, :my_integer_enum)
#=> [:foo, :bar, :baz]