Create dummy column name to keep expression-only indexes from colliding in table definition.

Fixes #8

Author: ronen

lib/schema_plus_pg_indexes/middleware/postgresql/migration.rb

@@ -12,11 +12,24 @@ def before(env)
  env.options[proper] = env.options.delete(deprecated)
  end
  end
+
+ case env.caller.class.name
+ when /TableDefinition/
+ # When index creation is in table definition, create a dummy value for column_names,
+ # since index definitions are indexed by column names
+ env.column_names = dummy_column_names(env) if env.column_names.blank?
+ else
+ # For actual index creation, strip out the dummy column name
+ # value
+ env.column_names = [] if env.column_names == dummy_column_names(env)
+ end
  end
- end
 
+ def dummy_column_names(env)
+ ["--expression--", env.options[:expression]]
+ end
+ end
  end
  end
  end
 end
-

spec/schema_spec.rb

@@ -22,6 +22,19 @@ class User < ::ActiveRecord::Base ; end
  expect(User.indexes.first.name).to eq("no_column")
  end
 
+ it "defines two indexes with expression only" do
+ define_schema do
+ create_table :users do |t|
+ t.string :one
+ t.string :two
+ t.index :expression => "upper(one)", name: "index_one"
+ t.index :expression => "upper(two)", name: "index_two"
+ end
+ end
+ expect(User.indexes.map(&:name)).to eq(["index_one", "index_two"])
+ expect(User.indexes.map(&:expression)).to eq(["upper((one)::text)", "upper((two)::text)"])
+ end
+
  it "defines index with expression as column option" do
  define_schema do
  create_table :users do |t|