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ecto_raw_sql_helpers

0.1.2
0.1.2

EctoRawSQLHelpers aims to improve raw SQL support in Ecto by providing helper functions, such as: - Named parameters support - Response parsing (getting query results as lists of maps, number of rows affected on statements, etc) - Stream support for dealing with big result sets

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ecto_raw_sql_helpers lib SQLStream.ex
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lib/SQLStream.ex 

defmodule EctoRawSQLHelpers.SQLStream do

  alias EctoRawSQLHelpers.DatabaseResponseParser

  alias EctoRawSQLHelpers.AdapterSQLExecutor

  alias EctoRawSQLHelpers.StreamServer



  def query(repo_or_pid, sql, params \\ [], options \\ []) do

    Stream.resource(

      fn -> AdapterSQLExecutor.adapter_query(repo_or_pid, sql, params, options) end,

      fn

        {:ok, %{columns: columns, rows: rows}} -> {[DatabaseResponseParser.convert_row_to_map(hd(rows), columns, options)], {columns, tl(rows)}}

        {columns, [row|tail]} -> {[DatabaseResponseParser.convert_row_to_map(row, columns, options)], {columns, tail}}

        {_columns, []} -> {:halt, :ok}

      end,

      fn _ -> :ok end

    )

  end



  def cursor(repo_or_pid, sql, params \\ [], options \\ []) do

    Stream.resource(

      fn -> StreamServer.initialize_stream_server_and_wait_for_demand(repo_or_pid, sql, params, options) end,

      fn pid -> handle_client_demand(pid, options) end,

      fn _ -> :ok end

    )

  end



  defp handle_client_demand(pid, options) do

    send(pid, %StreamServer.StreamRequest{client_pid: self(), instruction: :next_page})

    receive do

      %StreamServer.StreamResponse{server_pid: ^pid, state: :ok, data: data} -> {stream_rows_as_maps(data, options), pid}

      %StreamServer.StreamResponse{server_pid: ^pid, state: :finished} -> {:halt, :ok}

    end

  end



  defp stream_rows_as_maps(%{columns: columns, rows: rows}, options) do

    rows

    |> Enum.map(&DatabaseResponseParser.convert_row_to_map(&1, columns, options))

  end

end