Replace database for in memory storage

Phoenix Forum Questions / Help
1

I’m creating a new app in phoenix 1.3 where I don’t need database, it’s gonna be a sort of dashboard, but I still need context and schemas to represent some domain things. I was thinking of having a genserver where I can store these domain objects in a map. Now my question is, do I need ecto for this? I remember reading Programming Phoenix where at the beginning instead of using the database, some in memory storage was used. Is this something like this what I have to do? Or should I create a project with --no-ecto? in that case, if I want to create a new schema, do I still have to use changesets and so on?
What would be the best way to replace database storage for in memory storage?
thanks

2

If you still want to use ChangeSets (you mentioned schemas) the Using Ecto without a Repo may be of interest.

You can also use Erlang Term Storage: Optimizing Your Elixir and Phoenix projects with ETS.

Mnesia is a bit more involved.

3

I’ve been using Ecto for schemas, changesets, and validations to build out an Elasticsearch client. I’m using embedded_schemas.

Here’s a fairly contrived example, but this is sort of what I’m doing:

defmodule MySchema do
  use Ecto.Schema
  import Ecto.Changeset

  @primary_key false
  embedded_schema do
    field :my_field, :string
  end

  def changeset(schema, attrs) do
    # cast, validations, etc.
  end
end

attrs = %{ my_field: "Some Value" }
changeset = MySchema.changeset(%MySchema{}, attrs)
case changeset.valid? do
  true -> persist_changes # this could be to your local storage or wherever
  false -> handle_failure
end
4

In my case, I actually don’t really need changesets, what I need are schemas, as I need a way to represent let’s say a domain object. So I guess I need Ecto for this right? as schemas are from ecto, unless there is another structure I can use to represent a domain model?

5

You could use plain old structs. Using Changesets though will get you nice things like Ecto.Changeset.cast/4, which will handle type checking for you. If you simply need to structure your data you may be able to get away with structs though.

6

You don’t need Ecto per se. You can get by my defining your own struct that represents your domain using defstruct. Ecto.Schema automatically gives you a struct. If were to use an embedded_schema you would still get that but you would also have access to changesets. Changesets are fantastic for making sure data/fields exists whenever you want to do a CRUD operation.