CODEWITHSUNDEEP
couchdb
gtek
gtek

Reputation: 88

GETting a document within a Document Update Handler

Is it possible to query (GET) a document from within a document update handler in CouchDB?

I have written a simple document update handler in CouchDB 2.0 to accept a POST from a third party (CognitoForms). This works fine, and I take the ID from their JSON payload and use that as the doc _id.

You can then specify an 'update' URI in CognitoForms, so I could create a new update handler or use the same one. However, in CognitoForms:

As the ID for the document which needs to be updated is within the body, I could use this to query the database for the document, get the _rev, and return the payload with the _id and _rev to perform the update. However, I simply don't know if I can do such a query within the update handler. I feel like I am either missing something obvious, or there is a very good reason that I wouldn't be allowed to do that.

Thanks very much

edit: I should add that I understand I could create a small application to parse the request before forwarding on to couchdb, but I was interested to see if I could implement this in couchdb only to understand how far I can get without another layer!

Upvotes: 1

Views: 162

Answers (1)

Bernhard Gschwantner
Bernhard Gschwantner

Reputation: 1537

In your particular case, it's quite hard to do this. A document update handler is basically a pure function that gets the data it needs and returns a response, but it has no way to reach out into the database.

If you add a doc id to the url, the update function gets the doc from the database as a parameter. For details see the CouchDB docs for update functions.

The way to a possible solution is to use a rewrite in CouchDB in order to extract the id from the body. In CouchDB 2.0, a new way for rewrites as functions has been introduced.

For pushing the limits, using a rewrite function for this sounds like fun. But for a production use case, it's probably easier and more maintainable to create a small node.js app that parses the body.

Upvotes: 1

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