Retrieving site pages panics with "interface {} is *models.ListItem, not *models.SitePage"

[bittrance]

I have the following code which successfully processes the 196 first site pages before panicing:

func (c *Client) GetSitePage(ctx context.Context, siteID string, id string) (*models.SitePage, error) {
	idFilter := fmt.Sprintf("id eq '%s'", id)
	pages, err := c.client.Sites().BySiteId(siteID).Pages().GraphSitePage().Get(ctx, &sites.ItemPagesGraphSitePageRequestBuilderGetRequestConfiguration{
		QueryParameters: &sites.ItemPagesGraphSitePageRequestBuilderGetQueryParameters{
			Filter: &idFilter,
		},
	})
	if err != nil {
		return nil, err
	}
	pageIterator, err := msgraphcore.NewPageIterator[*models.SitePage](pages, c.client.GetAdapter(), models.CreateListItemCollectionResponseFromDiscriminatorValue)
	if err != nil {
		return nil, err
	}
	var page *models.SitePage
	err = pageIterator.Iterate(ctx, func(sitePage *models.SitePage) bool { // <-- panic on this row
		page = sitePage
		return false
	})
	return page, err
}

On 197 and all(?) subsequent IDs, it panics:

panic: interface conversion: interface {} is *models.ListItem, not *models.SitePage

goroutine 71 [running]:
github.com/microsoftgraph/msgraph-sdk-go-core.convertToPage[...]({0x2751b80, 0xc000abb6c0})
        github.com/microsoftgraph/msgraph-sdk-go-core@v1.0.1/page_iterator.go:228 +0x529
github.com/microsoftgraph/msgraph-sdk-go-core.(*PageIterator[...]).next(0x2fbf040?, {0x2fb41c8, 0xc00019a6e0?})
        github.com/microsoftgraph/msgraph-sdk-go-core@v1.0.1/page_iterator.go:136 +0x91
github.com/microsoftgraph/msgraph-sdk-go-core.(*PageIterator[...]).Iterate(0x2fbf040, {0x2fb41c8, 0xc00019a6e0}, 0xc00019a4b0)
        github.com/microsoftgraph/msgraph-sdk-go-core@v1.0.1/page_iterator.go:96 +0xc8
xxx.(*Client).GetSitePage(0xc000598d80, {0x2fb41c8, 0xc00019a6e0}, {0xc00005ea80, 0x24}, {0xc00089ce10, 0x24})
        mycode.go:181 +0x728

There does not appear to be anything particular about the triggering site page:

{
  "@odata.context": "https://graph.microsoft.com/beta/$metadata#sites('root')/pages/$entity",
  "@odata.type": "#microsoft.graph.sitePage",
  "@odata.etag": "\"{UUID},23\"",
  "createdDateTime": "2023-02-02T14:56:01Z",
  "eTag": "\"{UUID},23\"",
  "id": "uuid",
  "lastModifiedDateTime": "2023-03-02T10:19:59Z",
  "name": "Mypage.aspx",
  "webUrl": "https://zesite.sharepoint.com/SitePages/Mypage.aspx",
  "title": "Samtal",
  "pageLayout": "article",
  "thumbnailWebUrl": "https://zesite.sharepoint.com/_layouts/15/getpreview.ashx?path=mypage.jpg",
  "promotionKind": "page",
...
}

Issue arises on latest release v0.92.0.

Can someone help me make sense of this?

[bittrance]

I'm not sure exactly where the ListItem type in the panic message comes from, but I strongly suspect this issue is related to the fact that the pages endpoint seems not to implement $filter. I would have expected curl https://graph.microsoft.com/beta/sites/root/pages?\$filter=id %20eq%20'13082647-f439-4306-a874-ab4abc9dc5be' to return a single page, but it seems to return all of them. Filtering on other attributes are similarly ignored. Reformulating this method as

func (c *Client) GetSitePage(ctx context.Context, siteID string, id string) (*models.SitePage, error) {
	page, err := c.client.Sites().BySiteId(siteID).Pages().ByBaseSitePageId(id).GraphSitePage().Get(ctx, nil)
	if err != nil {
		return nil, err
	}
	return page.(*models.SitePage), err
}

works as expected. I'll close the issue since this is the beta API and should probably not be required to generate pedagogical error messages in corner cases.

[bittrance]

No sooner had I closed the issue than it arose in a related context. This code:

func (c *Client) GetSitePageSummaries(ctx context.Context, siteID string, visitor func(*models.SitePage) error) error {
	pages, err := c.client.Sites().BySiteId(siteID).Pages().GraphSitePage().Get(ctx, &sites.ItemPagesGraphSitePageRequestBuilderGetRequestConfiguration{
		QueryParameters: &sites.ItemPagesGraphSitePageRequestBuilderGetQueryParameters{
			Select: []string{"id", "name", "webUrl", "etag"},
		},
	})
	if err != nil {
		return err
	}

	pageIterator, err := msgraphcore.NewPageIterator[*models.SitePage](pages, c.client.GetAdapter(), models.CreateListItemCollectionResponseFromDiscriminatorValue) // <- panic: interface conversion: interface {} is *models.SitePage, not *models.BaseSitePage
	if err != nil {
		return err
	}
        // ...
}

generates the same issue. The interesting thing is that setting a large page size (i.e. giving a QueryParameters.Top of e.g. 1000) dodges the issue, so it seems to be somehow related to pagination.

[rkodev]

Hi @bittrance

Looking at the sample code looks like you are using the wrong constructor function , you can use this sample code instead

pageIterator, err := msgraphcore.NewPageIterator[*models.SitePage](pages, client.GetAdapter(), models.CreateSitePageCollectionResponseFromDiscriminatorValue)

I've created an issue to improve the type restriction for the users to as explore fixes for this issue here

[bittrance]

Changing the factory type seems indeed to address my problem. Thank you!