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Asynchronous CouchDB backend - part of Wallaby. The couchDB application framework.

Project description

Wallaby backend for CouchDB
===========================

This package provides an asynchronous python interface to CouchDB (using twisted).

For more information on wallaby visit http://wlby.freshx.de

Installation
============

You can install the couchdb backend with pip

```bash
pip install wallaby-backend-couchdb
```

How to use
==========

The library is based on twisted's asynchronous pattern. To use the library in an asynchronous fassion you
first need to create an reactor based application:

```python
from twisted.internet import defer

@defer.inlineCallbacks
def run():
# wait 1 second
d = defer.Deferred()
reactor.callLater(1.0, d.callback)
yield d

# stop the reactor and quit the application
reactor.stop()

from twisted.internet import reactor
reactor.callWhenRunning(run)
reactor.run()
```

Now we can connect to an existing CouchDB database:

```python
@defer.inlineCallbacks
def run():
# Create database client object
from wallaby.backends.couchdb import Database
db = Database(
"<name of database>",
username="<username>",
password="<password>",
url="http://localhost:5984"
)

# Query database info in an async manner
info = yield db.info()

# Output the info dict
print info

# <----- More example Code paste here

# stop the reactor and quit the application
reactor.stop()
```

Create and delete database
--------------------------

With the required permissions you could easily create and destroy databases

```python
newdb = Database(
"<name of new database>",
username="<username>",
password="<password>",
url="http://localhost:5984"
)

# Create the new database
res = yield newdb.create()

# Destroy the new database
res = yield newdb.destroy()
```

Read and write document
-----------------------

```python
# Get a document by id
doc = yield db.get('docid')

# add a new value to the document
doc['test'] = 'Hello World'

# save the document
res = yield db.save(doc)
```

Creating and deleting documents
-------------------------------

```python
# Create a new doc
doc = {'_id': 'newdocid'}
res = yield db.save(doc)

# the result contains the response from the CouchDB server
if not 'error' in res:
# the document was saved successfully. The new revision was updated in the "_rev" field of doc.
print doc['_rev']

# delete the document
res = yield db.delete(doc)
```

Attachment handling
-------------------

```python
# First we a load a file to attach. In real life you should do this in an async manner
content = open('test.png').read()

# Now we can attach this file to an existing document
res = yield db.put_attachment(doc, 'newimage.png', content, content-type='image/png')

# And load from database again
content = yield db.get_attachment(doc, 'newimage.png')

# and finally delete it
res = yield db.delete_attachment(doc, 'newimage.png')
```

Views
-----

```python
# get all rows of view
rows = yield db.view('_design/designname/_view/viewname')

# pass view arguments
rows = yield db.view('_design/designname/_view/viewname', count=100)
```

Changes
-------

```python
def callback(changes, viewID=None):
# all changes are passed to this callback as an array. the viewID help to identify
# view-based changes
pass

# register callback function for filtered changes
db.changes(cb=callback, since=12345, filter="couchappdoc/all")

# register callback function for view changes (only works in CouchDB 1.2)
db.changes(cb=callback, since=12345, filter="_view", view="couchappdoc/viewname")

# unregister first callback
db.unchanges(since=12345, filter="couchappdoc/all")

# unregister second callback
db.changes(since=12345, filter="_view", view="couchappdoc/viewname")
```

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