# `Localize.Ecto.Migration.Generator`
[🔗](https://github.com/elixir-localize/localize_sql/blob/v1.0.1/lib/localize/ecto/migration/generator.ex#L1)

Writes a migration file into a repository, for the migration-generating
mix tasks of `localize_sql`.

A tagged decimal type is installed by running SQL — `CREATE TYPE`, the
aggregate functions — inside an Ecto migration. Rather than ship the
SQL as a file the consumer copies, these tasks generate a migration
whose `up` and `down` embed the SQL produced by a `DDL` module, so the
statements are baked into the consumer's own timestamped migration and
are not affected by a later upgrade of `localize_sql`.

This module renders and writes that migration. `render/3` builds the
source and is independent of any repository; `create_migration/5`
writes it into a repository's migrations directory.

# `create_migration`

```elixir
@spec create_migration(module(), String.t(), String.t(), String.t(), String.t()) ::
  String.t()
```

Writes a migration into a repository's migrations directory.

### Arguments

* `repo` is an `Ecto.Repo` module.

* `name` is the migration name in snake case, such as
  `"add_cldr_unit"`. It is timestamped and camelized into the module
  name.

* `up_sql` is the body of the `up/0` function.

* `down_sql` is the body of the `down/0` function.

* `timestamp` is the 14-digit migration timestamp string, from
  `timestamp/0`.

### Returns

* The path of the written file.

# `render`

```elixir
@spec render(module(), String.t(), String.t()) :: String.t()
```

Renders a migration module as formatted Elixir source.

### Arguments

* `module` is the migration module name.

* `up_sql` is the body of the `up/0` function — typically the output
  of a `DDL.execute_each/1` call.

* `down_sql` is the body of the `down/0` function.

### Returns

* The migration source as a string.

### Examples

    iex> source = Localize.Ecto.Migration.Generator.render(
    ...>   MyApp.Repo.Migrations.AddCldrUnit,
    ...>   ~s|execute "CREATE TYPE public.cldr_unit AS (unit varchar, value numeric);"|,
    ...>   ~s|execute "DROP TYPE public.cldr_unit;"|
    ...> )
    iex> source =~ "def up do"
    true

# `timestamp`

```elixir
@spec timestamp() :: String.t()
```

Returns a 14-digit UTC timestamp for a migration filename.

### Returns

* The timestamp as a string, such as `"20260731090501"`.

---

*Consult [api-reference.md](api-reference.md) for complete listing*