Sqlcipher.Ecto

Important Note

This is a fork of the 'regular' sqlite variant (sqlite_ecto). It is not finished yet and lots of things might change later on. Proceed with care :)

Sqlcipher.Ecto is a SQLCipher Adapter for Ecto.

Read the tutorial for a detailed example of how to setup and use a SQLCipher repo with Ecto, or just check-out the CliffsNotes in the sections below if you want to get started quickly.

Dependencies

Sqlcipher.Ecto relies on Sqlcx and esqlcipher. Since esqlcipher uses Erlang NIFs, you will need a valid C compiler to build the library.

Example

Here is an example usage:

# In your config/config.exs file
config :my_app, Repo,
  adapter: Sqlcipher.Ecto,
  database: "ecto_simple.db",
  password: "password"        # this is optional!

# In your application code
defmodule Repo do
  use Ecto.Repo,
    otp_app: :my_app,
    adapter: Sqlcipher.Ecto
end

defmodule Weather do
  use Ecto.Model

  schema "weather" do
    field :city     # Defaults to type :string
    field :temp_lo, :integer
    field :temp_hi, :integer
    field :prcp,    :float, default: 0.0
  end
end

defmodule Simple do
  import Ecto.Query

  def sample_query do
    query = from w in Weather,
          where: w.prcp > 0 or is_nil(w.prcp),
         select: w
    Repo.all(query)
  end
end

Usage

Add Sqlcipher.Ecto as a dependency in your mix.exs file.

def deps do
  [{:sqlcipher_ecto, "~> 1.0.0"}]
end

You should also update your applications list to include both projects:

def application do
  [applications: [:logger, :sqlcipher_ecto, :ecto]]
end

To use the adapter in your repo:

defmodule MyApp.Repo do
  use Ecto.Repo,
    otp_app: :my_app,
    adapter: Sqlcipher.Ecto
end

Unsupported Ecto Constraints

The changeset functions foreign_key_constraint/3 and unique_constraint/3 are not supported by Sqlcipher.Ecto because the underlying SQLCipher database does not provide enough information when such constraints are violated to support the features.

Note that SQLCipher does support both unique and foreign key constraints via unique_index/3 and references/2, respectively. When such constraints are violated, they will raise Sqlcipher.Ecto.Error exceptions.

Silently Ignored Options

There are a few Ecto options which Sqlcipher.Ecto silently ignores because SQLite does not support them and raising an error on them does not make sense:

Most column options will ignore size, precision, and scale constraints on types because SQLCipher columns have no types, and SQLCipher won't coerce any stored value. Thus, all "strings" are TEXT and "numerics" will have arbitrary precision regardless of the declared column constraints. The lone exception to this rule are Decimal types which accept precision and scale options because these constraints are handled in the driver software, not the SQLCipher database.
If we are altering a table to add a DATETIME column with a NOT NULL constraint, SQLCipher will require a default value to be provided. The only default value which would make sense in this situation is CURRENT_TIMESTAMP; however, when adding a column to a table, defaults must be constant values. Therefore, in this situation the NOT NULL constraint will be ignored so that a default value does not need to be provided.
When creating an index, concurrently and using values are silently ignored since they do not apply to SQLite.

FelixKiunke / sqlcipher_ecto