Module: DynamicMigrations::Postgres::Generator::Index

Included in:
DynamicMigrations::Postgres::Generator
Defined in:
lib/dynamic_migrations/postgres/generator/index.rb

Instance Method Summary collapse

Instance Method Details

#add_index(index, code_comment = nil) ⇒ Object 



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# File 'lib/dynamic_migrations/postgres/generator/index.rb', line 5

def add_index index, code_comment = nil
  # the migration accepts either a single column name or an array of column names
  # we use the appropriate syntax just to make the migration prettier and easier
  # to understand
  column_names = (index.column_names.count == 1) ? ":#{index.column_names.first}" : "[:#{index.column_names.join(", :")}]"

  options = {
    name: ":#{index.name}",
    unique: index.unique,
    using: ":#{index.type}",
    # todo: support custom sorting, it requires refactoring the index class because the ordering is actually on a column by column basis, not the index itself
    sort: ":#{index.order}"
  }

  # :first is the default when :desc is specified, :last is the default when :asc is specified
  if (index.order == :desc && index.nulls_position == :last) || (index.order == :asc && index.nulls_position == :first)
    # todo: support nulls_position, it requires writing our own migrator because rails does not provide this option
    raise "custom nulls_position is not currently supported"
  end

  unless index.where.nil?
    options[:where] = "\"#{index.where}\""
  end

  unless index.description.nil?
    options[:comment] = <<~RUBY
      <<~COMMENT
        #{indent index.description}
      COMMENT
    RUBY
  end

  where_sql = ""
  unless index.where.nil?
    options[:where] = "#{index.name}_where_sql"
    where_sql = <<~RUBY
      #{index.name}_where_sql = <<~SQL
        #{indent index.where}
      SQL
    RUBY
  end

  options_syntax = options.map { |k, v| "#{k}: #{v}" }.join(", ")

  add_fragment schema: index.table.schema,
    table: index.table,
    migration_method: :add_index,
    object: index,
    code_comment: code_comment,
    migration: where_sql + <<~RUBY
      add_index :#{index.table.name}, #{column_names}, #{options_syntax}
    RUBY
end

#recreate_index(original_index, updated_index) ⇒ Object 



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# File 'lib/dynamic_migrations/postgres/generator/index.rb', line 70

def recreate_index original_index, updated_index
  # remove the original index
  removal_fragment = remove_index original_index, <<~CODE_COMMENT
    Removing original index because it has changed (it is recreated below)
    Changes:
      #{indent original_index.differences_descriptions(updated_index).join("\n")}
  CODE_COMMENT

  # recrete the index with the new options
  recreation_fragment = add_index updated_index, <<~CODE_COMMENT
    Recreating this index
  CODE_COMMENT

  # return the new fragments (the main reason to return them here is for the specs)
  [removal_fragment, recreation_fragment]
end

#remove_index(index, code_comment = nil) ⇒ Object 



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# File 'lib/dynamic_migrations/postgres/generator/index.rb', line 59

def remove_index index, code_comment = nil
  add_fragment schema: index.table.schema,
    table: index.table,
    migration_method: :remove_index,
    object: index,
    code_comment: code_comment,
    migration: <<~RUBY
      remove_index :#{index.table.name}, :#{index.name}
    RUBY
end

#remove_index_comment(index, code_comment = nil) ⇒ Object

remove the comment from a index



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# File 'lib/dynamic_migrations/postgres/generator/index.rb', line 108

def remove_index_comment index, code_comment = nil
  add_fragment schema: index.table.schema,
    table: index.table,
    migration_method: :remove_index_comment,
    object: index,
    code_comment: code_comment,
    migration: <<~RUBY
      remove_index_comment :#{index.table.name}, :#{index.name}
    RUBY
end

#set_index_comment(index, code_comment = nil) ⇒ Object

add a comment to a index



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# File 'lib/dynamic_migrations/postgres/generator/index.rb', line 88

def set_index_comment index, code_comment = nil
  description = index.description

  if description.nil?
    raise MissingDescriptionError, "Missing required description for index `#{index.name}` in table `#{index.table.schema.name}.#{index.table.name}`"
  end

  add_fragment schema: index.table.schema,
    table: index.table,
    migration_method: :set_index_comment,
    object: index,
    code_comment: code_comment,
    migration: <<~RUBY
      set_index_comment :#{index.table.name}, :#{index.name}, <<~COMMENT
        #{indent description}
      COMMENT
    RUBY
end