Handling error in absinthe

Questions / Help
,
1

I’m quite new to Elixir and Absinthe and I’m stuck trying to create a middleware to handle any kind of error when querying or mutating data.

For instance, I’m trying to query a User by id which I know doesn’t exist and I get the following (expected) error on the server and in the client:
(Ecto.NoResultsError) expected at least one result but got none in query

Is there any example to format the error so it shows something like this in the client:

{
  error: {
    code: 404,
    message: 'User not found',
  }
}
1 Like
2

Seems like you are using Ecto.Repo.get!/3 which throws the Ecto.NoResultsError exception without giving you a chance to react.

You should instead use Ecto.Repo.get/3 (note the lack of ! at the end) which returns either {:ok, record} or {:error, reason}, with the latter giving you a chance to return a HTTP 404 from your resolver.

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3

Please, a question. If there’s no time to react then why is this method present on the Repo? What’s its function exactly? You are right, I had the same problem and it fixed with what you proposed.

4

Hello and welcome,

it’s not as if You have no time to react, You just want to fail in case it’s not ok… like in the seed file.

1 Like
5

oh, I see. what you are saying is that with Repo.get!/3 the program will stop functioning ( will end ) in case of errors? And in the case of Repo.get/3 the program will continue working but it will return you a failing HTTP response?

6

Yes :slight_smile:

But You still can recover from an Exception with rescue.

1 Like
7

Thank you very much for your response and clarification. I’ve needing an answer to that weeks ago :wink:

8

The bang functions (those ending with !) usually throw an exception which can interrupt the program, yes.

The non-bang functions usually return tuples – {:ok, result} and {:error, details}.

It’s a good practice for library authors to provide both so people can make the call for themselves on which style do they want their program in.

2 Likes