On Sep 26, 2013, at 9:48 AM, Ashraf Janan <[email protected]> wrote:

> I have a document field :  Student with :_id, _rev , name: "Tom" , age : "37" 
> and i want to send message to Tom

You wouldn’t do that by adding to the Tom document. (What if two people decided 
to send messages?) You’d create a new document for the message, and put in a 
property containing Tom’s ID. Then you create a view to index messages by 
person -ID, to look up the messages for a person.

> * If i have the _id only for a student Tom,
>   Can i send a message to Tom direct?

No, because you’d end up blindly overwriting whatever was there before. You 
need to have the current contents and modify them, and then send them back, in 
order to detect conflicts. That way if someone else has made changes to the 
document since you last fetched it, the database will return a 409 error and 
you can retry again, resolving the conflict.

This is all described in detail in the book (guide.couchdb.org).

—Jens

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