different collections and fetched the fields

[tiyyagur...@gmail.com]

hi ,

i have number of collections but i don't know how many fields in documents .I want fetch the particular field in every collection but i don't know how to fetch the fields in all collections.

Any one knows please share your ideas.

PFA,

 my task is,I have four collections and every collection so many fields is there,  how to fetch the "date" field in all collections at a time. .

Thanking you,

T.k.r    

[Stephen Steneker]

Hi,

Can you share an example of the result you are trying to achieve given these four sample documents?

Thanks,

Stephen

[kran...@mantena.in]

Hi,

    I want the output like this       db.one.insert({"createdDate":""})

                                               db.two.insert({"createdDate":"2-9-15",

                                                                  "interviewDate":"2-7-15"})

                                               db.three.insert({"createdDate":""}) 

                                               db.four.insert({"createdDate":""})

 here i don't know field names but i want where is Date included filed i want that field 

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[John De Goes]

First, the fact that you want to solve this problem... is probably a problem in and of itself!

But regardless, what you want to do requires two operators which do not presently exist: $unravel and $typeof.

The hypothetical $unravel operator can split up a document into key/value pairs. The even more hypothetical $typeof operator can allow you to match for values of the date type (note that you can emulate $typeof currently, but I'm not going to explain how as it's quite complicated and not useful without $unravel).

You can vote for $unravel here. In the meantime, you can achieve what you want through map/reduce, by writing appropriate Javascript to iterate over document values and emit the fields that have a type of date.

Regards,

John