bson_iter_type(): precondition failed: iter->raw on find_pandas_all() about mongo-arrow HOT 6 CLOSED

Hi @kiritbasu, you could add a print statement before any place we call bson_iter_type with relevant local variables in lib.pyx, using a source install, or if you have an example document that causes the error we can take a look.

from mongo-arrow.

Thanks @blink1073 looks like the error happens when its trying to do extract_document_dtype - specifically value_t = bson_iter_type(doc_iter)

The specific type it fails on is this :
charts: [ { title: 'My Sessions by Region', chartType: 'LINE' }, { title: 'My Sessions by Country', chartType: 'LINE' }, ]
there are several instances where I have empty chart [] - i suspect its happening when its empty.

from mongo-arrow.

Ah, yes, that makes sense, thank you! I created https://jira.mongodb.org/browse/ARROW-158 to track this issue.

from mongo-arrow.

Thanks.
BTW something to consider is an ability to see some sort of progress when getting a large document. With regular pymongo I wouldn't care because I'd have to do the chunking/pagination myself, but because this is arrow, I'm more inclined to get large documents and so being able to understand where in the process I am and how much is left would be very useful for these fetch_all type operations.

from mongo-arrow.

Hi, I'm also getting this error.

mongo-arrow/bindings/python/mongo-c-driver-1.21.1/src/libbson/src/bson/bson-iter.c:477 bson_iter_type(): precondition failed: iter->raw

In my case, I can produce the error with a find by _id that returns a single document.

from mongo-arrow.

Fixed by 398d222

from mongo-arrow.