Params (including associations)

Every example needs params.

Params are described with the params function. It's typically first in an example's description, but it can be anywhere.

  bossie: [
    params(name: "Bossie", age: 10),
    ...
  ]

`params_like`

You can also use param_like to refer to an example previously described. Given the definition of :bossie above, the following two are equivalent:

  jake: [params(name: "Jake", age: 10)]

  jake: [params_like(:bossie, except: [name: "Jake"])]

Note: does params_like work if bossie used an `id-of`?

The :except can be omitted, in which case :jake would have the same params as :bossie.

The :except clause can add fields that aren't present in the original:

  params_like(:bossie, 
     except: [name: "Jake", species: "equine"])]

Ecto associations

Associations are handled by giving specific values to foreign keys. Consider an Animal schema with a belongs_to association to a Species schema. That's represented by giving a value to the Animal's species_id foreign key:

    params(name: "Bossie", species_id: ...)

Most likely, you don't want to give :species_id an explicit integer or GUID value. Instead, you want the database to create the Species row and use whatever value it gave as the primary key. That is accomplished as follows. Suppose you have a SpeciesExamples module containing a :bovine example:

  defmodule SpeciesExamples do
    use Template.EctoClassic.Insert

    def create_test_data do 
      start(...) |> 
      workflow(:success, 
        bovine: [params(...)])
    end
  end

Then :bossie can be created "within" species :bovine like this:

bossie: [params(
           name: "Bossie", 
           species_id: id_of(bovine: SpeciesExamples))])

At the moment, you can only fetch the primary key of another example, and that primary key must be named :id. All that's easily changed upon request.

The previous example showed how to refer to an example in a different module. If you want to use an example in the same module, you can abbreviate to just the example name:

bossie: [params(
           name: "Bossie", 
           mate_id: id_of(:ferdinand))]

Mechanism

Whenever an example is used, the very first step is to insert any other examples it depends on. Then those values are used to construct the examples params. If you trace the running of an example, you'll see those recursive creations. Here's an example of creating `:bossie

TBD: replace with bossie


> Run :duplicate_name (:constraint_error)
  :previously
    > Run :bossie (:success)
      :previously
        result: %{}
      :params
        params: %{"age" => "10", "date_string" => "2000-01-10", "name" => "Bossie"}
        result: %{"age" => "10", "date_string" => "2000-01-10", "name" => "Bossie"}
      :make_changeset
        result: #Ecto.Changeset<action: nil, changes: %{age: 10, date: ~D[2000-01-10], date_string: "2000-01-10", days_since_2000: 9, name: "Bossie"}, errors: [], data: #App.Schemas10.Named<>, valid?: true>
      :check_validation_changeset
      :insert_changeset
        result: {:ok, %App.Schemas10.Named{__meta__: #Ecto.Schema.Metadata<:loaded, "named">, age: 10, date: ~D[2000-01-10], date_string: "2000-01-10", days_since_2000: 9, id: 311, inserted_at: ~N[2020-12-09 00:59:07], name: "Bossie", updated_at: ~N[2020-12-09 00:59:07]}}
      :check_insertion
    < Run :bossie
    result: %{{:bossie, Examples.Schemas10.Named.Insert} => %App.Schemas10.Named{__meta__: #Ecto.Schema.Metadata<:loaded, "named">, age: 10, date: ~D[2000-01-10], date_string: "2000-01-10", days_since_2000: 9, id: 311, inserted_at: ~N[2020-12-09 00:59:07], name: "Bossie", updated_at: ~N[2020-12-09 00:59:07]}}
  :params
    params: %{"age" => "10", "date_string" => "2000-01-10", "name" => "Bossie"}
    result: %{"age" => "10", "date_string" => "2000-01-10", "name" => "Bossie"}
  :make_changeset
    result: #Ecto.Changeset<action: nil, changes: %{age: 10, date: ~D[2000-01-10], date_string: "2000-01-10", days_since_2000: 9, name: "Bossie"}, errors: [], data: #App.Schemas10.Named<>, valid?: true>
  :check_validation_changeset
  :insert_changeset
    result: {:error, #Ecto.Changeset<action: :insert, changes: %{age: 10, date: ~D[2000-01-10], date_string: "2000-01-10", days_since_2000: 9, name: "Bossie"}, errors: [name: {"has already been taken", [constraint: :unique, constraint_name: "named_name_index"]}], data: #App.Schemas10.Named<>, valid?: false>}
  :check_constraint_changeset
    result: #Ecto.Changeset<action: :insert, changes: %{age: 10, date: ~D[2000-01-10], date_string: "2000-01-10", days_since_2000: 9, name: "Bossie"}, errors: [name: {"has already been taken", [constraint: :unique, constraint_name: "named_name_index"]}], data: #App.Schemas10.Named<>, valid?: false>
< Run :duplicate_name