CouchDB - Querying array key value for first key element only

Question

I have a couchdb view set up using an array key value, in the format:

[articleId, -timestamp]

I want to query for all entries with the same article id. All timestamps are acceptable.

Right now I am using a query like this:

?startkey=["A697CA3027682D5JSSC",-9999999999999]&endkey=["A697CA3027682D5JSSC",0]

but I would like something a bit simpler.

Is there an easy way to completely wildcard the second key element? What would be the simplest syntax for this?

I believe all you need to do is ?startkey=["A697CA3027682D5JSSC"]&endkey=["A697CA3027682D5JSSC",{}] — Dominic Barnes
– Dominic Barnes, Commented Jul 24, 2012 at 3:19

Alex B · Accepted Answer · 2012-07-24 13:51:51Z

15

First, as a comment pointed out, there is indeed a special value {} that is ordered after any value, so your query becomes:

startkey=["target ID"]&endkey=["target ID",{}]

This is as equivalent to a wildcard match.

As a side note, there is no need to reverse the ordering in the map function by emitting a negative timestamp, you can reverse the order as an option to the view invocation (your start and end key will be swapped).

startkey=["target ID",{}]&endkey=["target ID"]&descending=true

answered Jul 24, 2012 at 13:51

Alex B

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4 Comments

Gopherkhan Over a year ago

Excellent. I was searching all over for this, but I guess my terminology was not exact. Thanks very much :)

MBillau Over a year ago

Where did you find this? it works great but I was scouring documentation for the last week and this is the first place I have seen the {} mentioned.

Alex B Over a year ago

@MBillau it's been too long, so I don't remember anymore. I think it had something to do with alphabetical ordering of {}.

bendtherules Over a year ago

@MBillau Docs link: docs.couchdb.org/en/1.6.1/couchapp/views/collation.html

jbgt · Accepted Answer · 2023-01-23 16:03:25Z

0

For future reference, in CouchDB 3 you can use "\ufff0" instead of {}, which would be ordered after a string or number, but before an object.

From the CouchDB 3 docs:

Beware that {} is no longer a suitable “high” key sentinel value. Use a string like "\ufff0" instead.

The query startkey=["foo"]&endkey=["foo",{}] will match most array keys with “foo” in the first element, such as ["foo","bar"] and ["foo",["bar","baz"]]. However it will not match ["foo",{"an":"object"}]

answered Jan 23, 2023 at 16:03

jbgt

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