I totally agree with you. The code I ended up with after some refactoring looks similar to yours, although I handle all of the error messages in the handle_ functions instead of defining them all in one place. I’m not sure if I’m entirely content with my code so far but the suggestions in this thread have helped me simplify and refactor a lot and I’m certainly happier with my code than I was before. Here it is for reference:
def insert(database, table, row) do
get_path(database, table)
|> File.read()
|> handle_file_read(database, table, row)
end
defp get_path(database, table) do
Path.join([Application.get_env(:simplexdb, :root_dir), database, table <> ".json"])
end
defp handle_file_read({:ok, content}, database, table, row) do
Logger.info "Successfully opened file for table #{table} in database #{database}!"
handle_decode(Poison.decode(content), database, table, row)
end
defp handle_file_read({:error, reason}, database, table, _row) do
Logger.error "Could not open file for table #{table} in database #{database} because of #{reason}!"
raise "File read error!"
end
defp handle_decode({:ok, content}, database, table, row) do
Logger.info "Successfully decoded JSON file for table #{table} in database #{database}!"
verify_key(content, database, table, row)
end
defp handle_decode({:error, {:invalid, reason}}, database, table, _row) do
Logger.error "Could not decode JSON in file for table #{table} in database #{database} because #{reason}!"
raise "Invalid JSON error!"
end
defp handle_decode({:error, :invalid}, database, table, row), do: handle_decode({:error, "it was invalid"}, database, table, row)
defp verify_key(content, database, table, row) do
if Map.has_key?(content, "rows") && is_list(content["rows"]) do
handle_encode(content, database, table, Poison.encode(row))
else
Logger.error "Invalid data key in JSON for #{table} in database #{database}!"
raise "Invalid JSON error!"
end
end
defp handle_encode(content, database, table, {:ok, row_content}) do
Logger.info "Successfully encoded row table #{table} in database #{database}!"
insert_data(content, database, table, row_content)
end
defp handle_encode(_content, database, table, {:error, reason}) do
Logger.error "Could not encode JSON in file for table #{table} in database #{database} because of #{reason}!"
raise "Invalid JSON error!"
end
defp insert_data(content, database, table, row_content) do
final_content = content
|> Map.update!("rows", fn rows -> rows ++ [row_content] end)
|> Poison.encode!()
get_path(database, table)
|> File.write(final_content)
|> handle_file_write(database, table)
end
defp handle_file_write(:ok, database, table) do
Logger.info "Successfully inserted new row in table #{table} in database #{database}!"
table
end
defp handle_file_write({:error, reason}, database, table) do
Logger.error "Could not write to file for table #{table} in database #{database} because of #{reason}!"
raise "File write error!"
end
The idea here was to get relatively granular error messages for the end user which would allow users to easily decipher what is wrong and fix it themselves.
