Sunday, May 8, 2011

Some basic couchdbkit 'views' (get it?)

We had to go to LA this weekend and I made my wife drive so I could learn up on CouchDB views. I had to re-read the Design Document and View sections of my O'Reilly book a couple times before it really clicked. Thankfully, the book is detailed enough that I didn't need to be looking at a database through Futon to get the point.

So today I hacked together a simple view in a Python script. This returns all my documents with a .symbol of 'C'. I'm not good at JavaScript (yet) so this is about as advanced as I want to get as I focus on Python and CouchDB:

design_doc = {
    '_id': '_design/test',
    'language': 'javascript',
    'views': {
        'allcitis': {
            "map": """function(doc) { if (doc.symbol == "C") { emit(doc._id, doc); }}"""

No problem - worked the first time and I saw it my Cloudant database. Parsing the view results through couchdbkit to a little longer to figure out. The Getting Started page ends with:

greets = Greeting.view('greeting/all’)

It took me a little while to figure out 'greets' wasn't a list, it's a couchdbkit.client.ViewResults. As it says in the comments for couchdbkit/, "It return an ViewResults object on which you could iterate, list, ...". Okay great, throw it in a list. Here's a trivial function to get the average of 'price' using the aforementioned view:

citis = list(frenzydb.view('/test/allcitis'))

sum = 0
for citi in citis:
    sum += float(dict(citi['value'])['price'])
print round(sum / len(citis), 2)

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