page iterator: reflect: call of reflect.Value.IsNil on zero Value

[stephenwan-opal]

Hello, I started seeing this error starting 2 days ago:

panic: goroutine 500907 [running]:
panic({0x2f8ccc0, 0xc01dd3a0d8})
	/usr/local/go/src/runtime/panic.go:884 +0x212
reflect.Value.IsNil(...)
	/usr/local/go/src/reflect/value.go:1554
github.com/microsoftgraph/msgraph-sdk-go-core.convertToPage({0x37b7280, 0xc00fd4ba80})
	/go/pkg/mod/github.com/microsoftgraph/msgraph-sdk-go-core@v0.31.0/page_iterator.go:205 +0x51b
github.com/microsoftgraph/msgraph-sdk-go-core.(*PageIterator).next(0xc00e8ee120?, {0x3ea9fd0?, 0xc00d369140?})
	/go/pkg/mod/github.com/microsoftgraph/msgraph-sdk-go-core@v0.31.0/page_iterator.go:126 +0x4e
github.com/microsoftgraph/msgraph-sdk-go-core.(*PageIterator).Iterate(0xc00e8ee120, {0x3ea9fd0, 0xc00d369140}, 0xc00d270500?)
	/go/pkg/mod/github.com/microsoftgraph/msgraph-sdk-go-core@v0.31.0/page_iterator.go:92 +0x5e
	<...snip...>
: reflect: call of reflect.Value.IsNil on zero Value

This looks similar to #249 and #224 but it is a different line of code panicking.

code looks like this:

iter, err := msgraphcore.NewPageIterator(
	users,
	s.client.GetAdapter(),
	models.CreateUserFromDiscriminatorValue,
)
if err != nil {
	return nil, azuread.WrapErr(err)
}
if err := iter.Iterate(ctx, func(item interface{}) bool {
	// ...
}

panicking code:

value := ref.FieldByName("value")
if value.IsNil() { // this line
	return page, errors.New("value property missing in response object")
}

which is different from the issue addressed by https://github.com/microsoftgraph/msgraph-sdk-go-core/pull/105/files.

[rkodev]

@stephenwan-opal could you kindly confirm if you are using v0.34.1 for package github.com/microsoftgraph/msgraph-sdk-go-core`, if not , could you upgrade and confirm if the error is still present?

[stephenwan-opal]

we are using 0.31.0. I will upgrade and take a look, thanks.

Did the API response change? Why would this issue start happening 3 days ago?

[rkodev]

@stephenwan-opal There isn't a change in the API response, this was a required change in the supporting library and was implement in core

[rkodev]

You can also upgrade to SDK v0.57.0

[stephenwan-opal]

Hi @rkodev, thanks - I guess I am confused on: why did I start seeing this issue 4 days ago, the same say microsoftgraph/msgraph-sdk-go-core#167 was put out? (is that coincidence? i.e. latent bug happens to show up on the same day?)

Doing this upgrade is unfortunately not straightforward for me. I tried to upgrade just the msgraph-sdk-go-core package but there are breaking changes up and downstream that require a bunch of things to be upgraded together. Because #129 is still an issue for me, the base msgraph-beta-sdk-go package is unusable for me, so I am doing this nasty hack to keep build times reasonable.

[baywet]

so I am doing this nasty hack to keep build times reasonable.

@stephenwan-opal the only part "nasty" about that solution is the fact that you're generating off a fork of this repo. You could perfectly generate your own client with only the API surface you care about in your project. In fact now that the tech to do so is mostly ready, we're working on lighting up experiences to make this easier to anybody who has stronger size/performance requirements than what the full SDK offers can use that option instead.

[stephenwan-opal]

sorry - I'd like to de-emphasize the specific change linked there. I'm excited to hear that the self-generated kiota build should help; at the time it was tricky to figure out and the kiota generation did not work out of the box (i.e. missing graph_service_client.go and some other files).

coming back to the issue at hand, do you have a sense when this issue gets triggered? is there a specific api response that doesn't return the value field?

[rkodev]

@stephenwan-opal /Perhaps a little context to help. This issue was brought about as a result of implementing the backing store. Values were no longer stored on the structs properties but were read from the backing store. The fix was to invoke the GetValue method via reflection as opposed to reading the value property. If it helps this the specific change that was done microsoftgraph/msgraph-sdk-go-core#167

[rkodev]

Hi @stephenwan-opal, I'll be closing this ticket since its been a while. If you still need some more assistance, you can comment and re-open it