Data preview fails for data.frames that are part of another object

[jonvanausdeln]

System details

RStudio Edition : Desktop (all)
RStudio Version : 2023.06.1-438
OS Version      : All
R Version       : All

Steps to reproduce the problem

From #13188 (comment)

test_df <- data.frame(col1 = rep(1, 3),
                      col2 = rep(2, 3),
                      col3 = rep(3, 3))

test_ls <- list(a = test_df,
                b = test_df)

Describe the problem in detail

test_ls$ + tab , won't show the dataframe preview

Describe the behavior you expected

preview of data should show as part of autocomplete

• I have read the guide for submitting good bug reports.
• I have installed the latest version of RStudio, and confirmed that the issue still persists.
• If I am reporting an RStudio crash, I have included a diagnostics report.
• I have done my best to include a minimal, self-contained set of instructions for consistently reproducing the issue.

[sharon-wang]

Looking into why we are unable to find the object (and thus can't load the data frame preview)...

Note the differences between the grid_data request payload:

In particular, env and cache_key look pretty different from CB to the MH releases. I think we're having trouble locating test_ls$a because of these values changing.

2023.6.1 - response error

{"error":"The object no longer exists."}

2023.06.0 - response error

{"error":"r error 4 (Error in if (maxRows != -1 && nrow(data) > maxRows) data <- head(data,  : \n  missing value where TRUE/FALSE needed\n)"}

2023.03.0 - data retrieved successfully

---

Paraphrased from @kevinushey:

Note that the cache key was removed in 2023.6.0 because we don't have a good way to "invalidate" the cached object (the object sticks around for the rest of the session).

When using cache keys, the object sticking around can result in a "stale" object being shown in the help data preview popup, so the preview might be for a different object than the one the user is actually trying to preview.

---

So we'll want to avoid re-introducing the cacheKey in the fix, or at least avoid the mismatched object preview issue.

[jonvanausdeln]

Verified on Desktop 2023.09.0-daily+217

Autocomplete works as expected.