Ecto.Model.Callbacks
Define module-level callbacks in models.
A callback is invoked by your Ecto.Repo before (or after)
particular events. Callbacks receive changesets, must
always a changeset back and always run inside a transaction.
Example
defmodule User do
use Ecto.Model.Callbacks
after_insert Stats, :increase_user_count
def increase_user_count(changeset)
# ...
end
end
When creating the user, the after_insert callbacks will be
invoked with a changeset as argument. Multiple callbacks
can be defined, they will be invoked in order of declaration.
A callback can be defined in the following formats:
# Invoke the local function increase_user_count
after_insert :increase_user_count
# Invoke the local function increase_user_count
# with the given arguments (changeset is prepended)
after_insert :increase_user_count, ["foo", "bar"]
# Invoke the remote function increase_user_count
after_insert Stats, :increase_user_count
# Invoke the remote function increase_user_count
# with the given arguments (changeset is prepended)
after_insert Stats, :increase_user_count, ["foo", "bar"]
Usage
Callbacks in Ecto are useful for data consistency, for keeping counters, setting changes and so on. Avoid using callbacks for business rules or doing actions unrelated to the data itself, like sending e-mails.
Finally, keep in mind callbacks are not invoked on bulk actions
such as Repo.delete_all or Repo.update_all.
Summary↑
| __apply__(module, callback, changeset) | Applies stored callbacks in model to given data |
| after_delete(function, args \\ []) | Adds a callback that is invoked before the model is deleted from the repository |
| after_delete(module, function, args) | Same as |
| after_insert(function, args \\ []) | Adds a callback that is invoked after the model is inserted into the repository |
| after_insert(module, function, args) | Same as |
| after_update(function, args \\ []) | Adds a callback that is invoked after the model is updated |
| after_update(module, function, args) | Same as |
| before_delete(function, args \\ []) | Adds a callback that is invoked before the model is deleted from the repository |
| before_delete(module, function, args) | Same as |
| before_insert(function, args \\ []) | Adds a callback that is invoked before the model is inserted into the repository |
| before_insert(module, function, args) | Same as |
| before_update(function, args \\ []) | Adds a callback that is invoked before the model is updated |
| before_update(module, function, args) | Same as |
Functions
Applies stored callbacks in model to given data.
Checks wether the callback is defined on the model, returns the data unchanged if it isn't.
This function expects a changeset as input.
Examples
iex> changeset = Ecto.Changeset.cast(params, %User{}, ~w(name), ~w())
iex> Ecto.Model.Callbacks.__apply__ User, :before_delete, changeset
%Ecto.Changeset{...}
Macros
Adds a callback that is invoked before the model is deleted from the repository.
The callback receives an Ecto.Changeset with the model
stored in it. The callback must return a changeset.
Example
after_delete User, :notify_garbage_collectors
Same as after_delete/2 but with arguments.
Adds a callback that is invoked after the model is inserted into the repository.
The callback receives an Ecto.Changeset with both repository
values and changeset changes already applied to the model.
The callback must return a changeset.
Example
after_insert Stats, :increase_user_count
Same as after_insert/2 but with arguments.
Adds a callback that is invoked after the model is updated.
The callback receives an Ecto.Changeset with both repository
values and changeset changes already applied to the model.
The callback must return a changeset.
Example
after_update User, :notify_account_change
Same as after_update/2 but with arguments.
Adds a callback that is invoked before the model is deleted from the repository.
The callback receives an Ecto.Changeset. Although the changes
field is ignored by the repository on delete, future functionality
will allow pre-conditions to be set on delete.
Example
before_delete User, :copy_to_archive
Same as before_delete/2 but with arguments.
Adds a callback that is invoked before the model is inserted into the repository.
Since on insert all the model fields plus changeset changes
are sent to the repository, the callback will receive an
Ecto.Changeset with all the model fields and changes in
the changeset.changes field. The callback must return a
changeset.
Example
before_insert User, :generate_permalink
Same as before_insert/2 but with arguments.
Adds a callback that is invoked before the model is updated.
The callback receives an Ecto.Changeset with the changes
to be sent to the database in the changeset.changes field.
The callback must return a changeset.
Example
beforeupdate User, :setupdateattimestamp
Same as before_update/2 but with arguments.