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improvement: add error handler improvement: translatable error messages docs: handle errors guide
82 lines
No EOL
2.2 KiB
Markdown
82 lines
No EOL
2.2 KiB
Markdown
# Handling Errors
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There are various options that can be set on the Api module to determine how errors behave and/or are shown in the GraphQL.
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## Showing raised errors
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For security purposes, if an error is *raised* as opposed to returned somewhere, the error is hidden. Set this to `true` in dev/test environments for an easier time debugging.
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```elixir
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graphql do
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show_raised_errors? true
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end
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# or it can be done in config
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# make sure you've set `otp_app` in your api, i.e use Ash.Api, otp_app: :my_app
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config :my_app, YourApi, [
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graphql: [
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show_raised_errors?: true
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]
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]
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```
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## Root level errors
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By default, action errors are simply shown in the `errors` field for mutations. Set this to `true` to return them as root level errors instead.
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```elixir
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graphql do
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root_level_errors? true
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end
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```
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## Error Handler
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Setting an error handler allows you to use things like `gettext` to translate errors and/or modify errors in some way. This error handler will take the error object to be returned, and the context. See the [absinthe docs](https://hexdocs.pm/absinthe/context-and-authentication.html#context-and-plugs) for adding to the absinthe context (i.e for setting a locale).
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```elixir
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graphql do
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error_handler {MyApp.GraphqlErrorHandler, :handle_error, []}
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end
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```
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Keep in mind, that you will want to ensure that any custom error handler you add performs the logic to replace variables in error messages.
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This is what the default error handler looks like, for example:
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```elixir
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defmodule AshGraphql.DefaultErrorHandler do
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@moduledoc "Replaces any text in message or short_message with variables"
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def handle_error(
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%{message: message, short_message: short_message, vars: vars} = error,
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_context
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) do
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%{
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error
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| message: replace_vars(message, vars),
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short_message: replace_vars(short_message, vars)
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}
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end
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def handle_error(other, _), do: other
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defp replace_vars(string, vars) do
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vars =
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if is_map(vars) do
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vars
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else
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List.wrap(vars)
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end
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Enum.reduce(vars, string, fn {key, value}, acc ->
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if String.contains?(acc, "%{#{key}}") do
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String.replace(acc, "%{#{key}}", to_string(value))
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else
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acc
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end
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end)
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end
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end
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``` |