In this specific case I would avoid using pipes as for example reduce on fields requires to write Map.put/3 only once and therefore allows to focus on working on data. Also if you are updating map/struct key value then you can simply use %{map | existing_key: new_value} syntax which is short and nice.
Here are 2 examples … First goes short update map:
project = Clients.get_project!(id)
budget = total_budget(project.budget_items)
budget_used = budget_used(project.work_items)
updated_project = %{project | budget: budget, budget_used, budget_remaining: budget - budget_used}
Second example shows usage of reduce:
defmodule Project do
defstruct [:budget, :budget_items, :budget_remaining, :budget_used, :work_items]
def calculate(project) do
fields = [:budget, :budget_used, :budget_remaining]
Enum.reduce(fields, project, fn key, acc ->
value = Project.calculate(project, key)
Map.put(project, key, value
end)
# short notation:
# updated_project = Enum.reduce(fields, project, &Map.put(&2, &1, Project.calculate(&2, &1))
end
def calculate(%{budget_items: items}, :budget), do: total_budget(items)
def calculate(%{work_items: items}, :budget_used), do: budget_used(items)
def calculate(%{budget: budget, budget_used: used}, :budget_remaining), do: budget - used
end
project = id |> Clients.get_project!() |> Project.calculate()
