SeedHelper

SeedHelper provides some simple schem and utilities for supporting incremental seeding of data in Ecto with out requiring a full teardown/setup to obtain consistent data sets.

Features

Track versioned seed sections

Run a seed only if it has not already been applied to current database.

require SeedHelper
import SeedHelper

seed({"MySeed", "1"}) do
  IO.puts "Seeding database..."
  # Write data here.
end

Specify seed dependencies.

Wait until required Seed.Version has been applied before executing block.

require SeedHelper
import SeedHelper

requires_seed({"MySeed", "2"}) do
  seed({"MySeed", "1"}) do
    IO.puts "Seeding database... 1"
  end
end

# Seed 1 will be queued into an agent until {"MySeed"",2} has executed. 
seed({"MySeed", "2"}) do
  IO.puts "Seeding database... 2"
end

Specify environment dependencies.

Only apply seeds in test environments, prod, dev, etc.

require SeedHelper
import SeedHelper

if_env([:prod,:stage]) do
  IO.puts "Running in production or staging environment"
   seed({"MySeed", "1"}) do
    IO.puts "Seeding database... 1"
  end 
end

if_env(:test) do 
  IO.puts "Running in test environment"
  requires_seed({"MySeed", "Core"}) do
    seed({"MySeed", "test-data"}) do
      IO.puts "Seeding database... test-data"
    end
  end
end

seed({"MySeed", "stuff"}) do
  IO.puts "Seeding database... stuff"
  if_env(:test) do
    IO.puts "Test Specific Stuff"
  end
end

Set and Lookup handles

This is useful when inserted data used generated ids but needs to be referenced by other seeds. handles are stored to the SeedHelper.Schema.Handles (seed_helpers_handles) table but loaded/fetched during session from an etc cache to avoid perf issues with large data sets/frequent look ups.

require SeedHelper
import SeedHelper

seed({"MySeed", "core"}) do
    IO.puts "Seeding database... core"
    # Save some record with dynamic id.
    set_handle("record.id", record.id)
end

# .
# .
# .

seed({"MySeed", "links"}) do
    record_id = get_handle("record.id", :or_apple_if_nil)
    # Save record referencing record_id    
end

Setup

1. Add SeedHelper to your mix.exs file.

   defp deps do
     [
       {:seed_helper, "~> 0.1.0"}
     ]
   end
   

2. Set config.exs set repo for seed helper.

   config :seed_helper, repo: MyApp.Repo
   

3. Setup migration

   Run:

   mix ecto.gen.migration setup_seed_helper 
   

   Edit migration file:

   defmodule MyApp.Repo.Migrations.SetupSeedHelper do
     use Ecto.Migration
   
     def up() do 
       SeedHelper.Migration.up(1)
     end
   
     def down() do 
       SeedHelper.Migration.down(1)
     end
   end
   

4. Start SeedHelper session in your priv/repo/seeds.exs file

   require SeedHelper
   import SeedHelper
   
   # Begin SeedSession (Agent for requires_seed blocks and etc table for handle cache
   begin_session()
   
   dir = Path.dirname(__ENV__.file)
   Code.eval_file("#{dir}/seeds/#{Mix.env}-seeds.exs")
   
   # Will throw if and requires_seeds blocks were not resolved during execution. 
   :ok = end_session()