IntrospectionQuery fails when dataMasking is enabled

[jwatzman]

Intended outcome:

When I open the developer tools in my app and then go to the "explorer" tab, I get an error:

Schema Introspection Failure
We couldn't parse your graphql schema, or building your schema failed. The expected format is either IntrospectionQuery or SDL string.

This causes the autocomplete and other nice features of the "explorer" tab not to work properly -- though executing a query works just fine if I manually compose one.

After some debugging, I'm pretty sure that the issue is due to my app's use of fragment / data masking -- I believe masked data is getting sent back to the client, which means that the data that it wants isn't actually there since the IntrospectionQuery uses fragments.

Changing my call to new ApolloClient in my app from dataMasking: true to dataMasking: false fixes the issue and allows autocomplete etc to work fine.

Actual outcome:

I'd expect the dev tools to work just fine whether or not my app uses data masking.

How to reproduce the issue:

Pass dataMasking: true as an argument to new ApolloClient.

Desktop (please complete the following information):

• OS: Windows 10
• Browser: Firefox
• Browser version: 141
• Extension version: 4.18.15

[phryneas]

That's a really good finding, thank you for reporting!

We're currently deep in finishing Apollo Client 4.0, but that means that we soon have to take a look at the DevTools, and in that context we'll try to fix this issue.