Post request got an InvalidBody error

How does your resouce look like?

defmodule MyApp.Students do
  use Ash.Domain, extensions: [AshJsonApi.Domain]

  authorization do
    authorize :by_default
  end

  resources do
    resource MyApp.Students.Student
  end
end

defmodule MyApp.Students.Student do
  use Ash.Resource,
    domain: MyApp.Students,
    data_layer: AshPostgres.DataLayer,
    extensions: [
      AshJsonApi.Resource
    ]

  json_api do
    type "student"

    routes do
      base("/students")

      get(:stud, route: "/student")
      index :read
      post(:create)
      patch(:update)
      delete(:destroy)
      get(:login)
    end
  end

  actions do
    read :read do
      primary? true
    end

    create :create
    update :update
    destroy :destroy
  end

  postgres do
    table "students"
    repo MyApp.Repo
  end

  attributes do
    uuid_primary_key :id

    attribute :first_name, :string do
      allow_nil? false
    end

    attribute :last_name, :string do
      allow_nil? false
    end

    create_timestamp :inserted_at
    update_timestamp :updated_at
  end
end

Two things:

First, The reason for this specific error is that the first and last name are not accepted by the actions. You probably want:

create :create do
  accept [:first_name, :last_name]
end

update :update do
  accept [:first_name, :last_name]
end

second, you likely want to make the first and last name attributes public? so that they display in the API.

Thanks, @zachdaniel @kamaroly, It works good.

The following should also work.

  actions do
    # ========Add this line============
    default_accept  [:first_name, :last_name]
  end