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From: Sander Dijkhuis <mail@sanderdijkhuis.nl>
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Subject: Decimal values in JSON
Message-Id: <DBDA5572-F8E9-433D-B7BB-77C72248E1FF@sanderdijkhuis.nl>
Date: Tue, 16 Apr 2013 13:34:48 +0200
To: user@couchdb.apache.org
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Hi,

I=92m working on a CouchDB design doc that provides a Cosm-like API to =
work with sensor measurements. I know that the CouchDB guide recommends =
using strings to represent decimal values in JSON[1], but was curious to =
try using the { "field": 4.2 } format as it gives a cleaner API. I =
figured that as long as data is sent in the right format, CouchDB might =
handle it well as JSON doesn=92t specify that decimals should be =
considered as floats.

So far my update handler measurement(doc, req) seems to process the data =
correctly. The raw req.body input string contains the value represented =
with { "field": 4.2 }, and after JSON-parsing the input (but not =
changing the decimal field), the =91doc=92 variable that=92s sent back =
to CouchDB still seems to contain the field as 4.2, at least as shown by =
log(JSON.stringify(doc)).

Only when I request the _changes feed, any map/reduce view or a =
particular doc, the value comes out of CouchDB as { "field": =
4.200000000002 } in JSON. I wonder if this is a bug in CouchDB? Or did =
the log(doc) already deceive me and use different JSON serialisation =
than CouchDB uses when processing the update handler=92s output?

Sander

[1] http://guide.couchdb.org/draft/json.html#numbers