Basics

This check has a base priority of normal and works with any version of Elixir.

Explanation

Encourages reading schema fields off an Ecto.Changeset via Ecto.Changeset.get_field/2 rather than direct struct access (changeset.changes.field, changeset.data.field) or Access (changeset[:field]).

get_field/2 returns the post-cast value: it transparently picks the change if one is present, falls back to the original data otherwise, and respects embeds. Reaching into :data or :changes by hand only sees one layer and easily reads a stale value when both exist. changeset[:key] is a friendlier shortcut for the same direct access and shares the pitfall.

Reads of the %Ecto.Changeset{} struct's own fields (changeset.valid?, changeset.data, changeset.errors, changeset.action, etc.) are not flagged — those are legitimate uses of the struct's public API, not schema-field access.

To limit false positives, the check only runs against files that import or alias Ecto.Changeset somewhere in the source — this keeps it from flagging unrelated variables that happen to be named changeset (e.g. struct fields, helper params).

Bad

name = changeset.changes.name
email = changeset.data.email
age = changeset[:age]

Good

name = Ecto.Changeset.get_field(changeset, :name)
email = Ecto.Changeset.get_field(changeset, :email)
age = Ecto.Changeset.get_field(changeset, :age)

Check-Specific Parameters

There are no specific parameters for this check.

General Parameters

Like with all checks, general params can be applied.

Parameters can be configured via the .credo.exs config file.