CouchDB Document Update Handlers (in-place updates)?

The example function in-place is not the same as "in-place" updates in other databases. CouchDB still uses an append-only architecture; document update handlers still create a new doc revision, etc Still, update handlers are quite convenient and worth learning Suppose you have a document with an accumulator. You want to accumulate an integer in a document with just one HTTP query, specifying the increment amount using an amount parameter.

Consider the following commands: curl -X PUT localhost:5984/db # Returns {"ok":true} curl -X POST localhost:5984/db/_bulk_docs -d @- {"docs": {"_id": "my_doc", "number": 23}, {"_id": "_design/app", "updates": { "accumulate": "function (doc, req) { var inc_amount = parseInt(req.query. Amount); doc. Number = doc.

Number + inc_amount; return doc, \"I incremented \" + doc. _id + \" by \" + inc_amount; }" } } } # Returns {"id":"my_doc","rev":"1-8c9c19a45a7e2dac735005bbe301eb15"}, # {"id":"_design/app","rev":"1-83ec85978d1ed32ee741ce767c83d06e"} (Remember to press end-of-file, ^D, after the JSON object in the POST. ) Next confirm the document for accumulation ( my_doc ) exists: curl localhost:5984/db/my_doc # Returns {"_id":"my_doc","_rev":"1-8c9c19a45a7e2dac735005bbe301eb15", # "number":23} Now you can call the accumulate update handler with an amount parameter to update the field curl -X PUT \ localhost:5984/db/_design/app/_update/accumulate/my_doc?

Amount=15 # Returns: I incremented my_doc by 15 curl localhost:5984/db/my_doc # Returns {"_id":"my_doc","_rev":"2-", # "number":38} Notice that the new number value is 38, the value of 23 + 15.

The example function in-place is not the same as "in-place" updates in other databases. CouchDB still uses an append-only architecture; document update handlers still create a new doc revision, etc. Still, update handlers are quite convenient and worth learning. Suppose you have a document with an accumulator.

You want to accumulate an integer in a document with just one HTTP query, specifying the increment amount using an amount parameter. Consider the following commands: curl -X PUT localhost:5984/db # Returns {"ok":true} curl -X POST localhost:5984/db/_bulk_docs -d @- {"docs": {"_id": "my_doc", "number": 23}, {"_id": "_design/app", "updates": { "accumulate": "function (doc, req) { var inc_amount = parseInt(req.query. Amount); doc.

Number = doc. Number + inc_amount; return doc, \"I incremented \" + doc. _id + \" by \" + inc_amount; }" } } } # Returns {"id":"my_doc","rev":"1-8c9c19a45a7e2dac735005bbe301eb15"}, # {"id":"_design/app","rev":"1-83ec85978d1ed32ee741ce767c83d06e"} (Remember to press end-of-file, ^D, after the JSON object in the POST.

) Next confirm the document for accumulation (my_doc) exists: curl localhost:5984/db/my_doc # Returns {"_id":"my_doc","_rev":"1-8c9c19a45a7e2dac735005bbe301eb15", # "number":23} Now you can call the accumulate update handler with an amount parameter to update the field. Curl -X PUT \ localhost:5984/db/_design/app/_update/accumulate/my_doc? Amount=15 # Returns: I incremented my_doc by 15 curl localhost:5984/db/my_doc # Returns {"_id":"my_doc","_rev":"2-", # "number":38} Notice that the new number value is 38, the value of 23 + 15.

The _rev value increments on updates though. – PartlyCloudy Feb 18 at 22:23 Whoops, fixed. Thanks.

– JasonSmith May 17 at 1:48.

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