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Building Database Applications in Elixir with Ecto

Generate a Form for a Single Schema

Explore how to generate a form for a single schema using Ecto changesets within Phoenix. Learn to define a user schema, set up a controller action, build a form with form_for, and process form submissions to create user records. Understand changeset validation and error handling to create dynamic, user-friendly forms.

We'll cover the following...

Set up a simple schema

Let’s set up a simple User schema as a starting point. We’ll define fields for name and age and add a changeset function that will cast and validate incoming parameters.

Elixir
defmodule MyApp.User do 
  import Ecto.Changeset 
  use Ecto.Schema
  schema "users" do 
    field :name, :string 
    field :age, :integer
  end
  
  def changeset(user, params) do 
    user
    |> cast(params, [:name, :age])
    |> validate_required(:name)
    |> validate_number(:age, greater_than: 0,
         message: "you are not yet born")
  end 
  
end

Define new action on the controller

Next, we’ll need a controller. When we invoke the new action on the controller, we want to return a new, empty changeset for a User, as shown below.

Elixir
def new(conn, _params) do
  changeset = User.changeset(%User{}, %{}) 
  render(conn, changeset: changeset)
end

Set up the form

Now we’re ready to set up the form. To build forms from ...