Merge pull request #203 from kedar2a/master

Documentation for 'Pagination' added

doc/paginator.txt

@@ -0,0 +1,161 @@
+=================
+Using `Paginator`
+=================
+
+Implementing pagination in the project is made easy with ``mongokit.paginator.Paginator``.
+``Paginator`` actually converts query-result-cursor into Paginator object and provides useful properties on it.
+
+Using `Paginator` is consists of following two logical steps:
+
+1. Importing `paginator.Paginator` module.
+2. Applying it on your query-result-cursor.
+
+Lets apply this steps with following detailed example.
+
+-------------------
+
+A detailed Example:
+-------------------
+
+Consider following as a sample model class:
+
+>>> from mongokit import Document, Connection
+...
+... connection = Connection()
+...
+... @connection.register
+... class Wiki(Document):
+...
+...    __collection__ = 'wiki'
+...    __database__ = 'db_test_pagination'
+...
+...    structure = {
+...        "name": unicode,  # name of wiki
+...        "description": unicode,  # content of wiki
+...        "created_by": basestring,  # username of user
+...    }
+...
+...    required_fields = ['name', 'created_by']
+
+Now let's consider that you have created 55 instances of class Wiki. And while querying you are getting all the instances in a query-result-cursor or resultant cursor.
+
+.. Query to fetch all the 55 instances of Wiki class.
+
+>>> wiki_collection = connection['db_test_pagination']
+>>> total_wikis = wiki_collection.Wiki.find()
+>>> total_wikis.count()
+... 55
+
+-----
+
+**Now let's paginate the resultant cursor:** ``total_wikis``
+
+As stated previously, we will first import the ``Paginator`` and then apply pagination on the resultant cursor.
+
+>>> from mongokit.paginator import Paginator
+
+>>> page_no = 2  # page number
+>>> no_of_objects_pp = 10  # total no of objects or items per page
+
+Keyword arguments required for ``Paginator`` class are as follows:
+ 1. ``cursor`` -- Cursor of a returned query   (``total_wikis`` in our example)
+ 2. ``page``   -- The page number requested    (``page_no`` in our example)
+ 3. ``limit``  -- The number of items per page (``no_of_objects_pp`` in our example) 
+
+>>> paged_wiki = Paginator(total_wikis, page_no, no_of_objects_pp)
+
+We had applied the pagination on ``total_wikis`` cursor and stored it's result in ``paged_wiki``, which is a Paginated object.
+
+:Note:
+	  The cursor (``total_wikis``) which we passed as an argument for ``Paginator``, also gets limit to ``no_of_objects_pp`` (``10`` in our case). And looping it would loop for ``no_of_objects_pp`` (``10``) times.
+
+------
+
+**Paginated object properties:**
+
+.. We are going to work with `paged_wiki`, (no. of pages = 2) and (no. of item's per page = 10).
+.. (Continuing the same above example.) 
+
+Let's move ahead and try properties on ``paged_wiki``. There are total of 11 properties provided by mongokit, for the Paginated object. The properties that we can apply on ``paged_wiki`` are as follows:
+
+property-1: **items** -- *Returns the paginated Cursor object.*
+
+.. Note: As ``paged_wiki`` is ``Paginator`` object it cannot iterate directly. Doing so will give an error - "'Paginator' object is not iterable". To do so we have the property of ``.items``.
+
+>>> for each in paged_wiki.items:
+...     print each['name']
+...     #  do your stuff ..
+
+Above code will loop for 10 times to print the name of objects.
+
+
+Property-2: **is_paginated** -- *Boolean value determining if the cursor has multiple pages*
+
+>>> paged_wiki.is_paginated
+... True
+
+
+Property-3: **start_index** -- *int index of the first item on the requested page*
+
+>>> paged_wiki.start_index
+... 11
+
+As the no. of items per page is ``10``, we got the result of second page's, starting item's index as ``11``.
+
+
+Property-4: **end_index**  -- *int index of the last item on the requested page*
+
+>>> paged_wiki.end_index
+... 20
+
+As the no. of items per page is ``10``, we got the result of second page's, ending item's index as ``20``.
+
+
+Property-5: **current_page** -- *int page number of the requested page*
+
+>>> paged_wiki.current_page
+... 2
+
+
+Property-6: **previous_page** -- *int page number of previous page with respect to current requested page*
+
+>>> paged_wiki.previous_page
+... 1
+
+
+Property-7: **next_page** -- *int page number of next page with respect to current requested page*
+
+>>> paged_wiki.next_page
+... 3
+
+
+Property-8: **has_next** -- *True or False if the Cursor has a next page*
+
+>>> paged_wiki.has_next
+... True
+
+
+Property-9: **has_previous** -- *True or False if the Cursor has a previous page*
+
+>>> paged_wiki.has_previous
+... True
+
+
+Property-10: **page_range** -- *list of the all page numbers (ascending order) in a list format*
+
+>>> paged_wiki.page_range
+... [1, 2, 3, 4, 5, 6]
+
+
+Property-11: **num_pages** -- *int of the total number of pages*
+
+>>> paged_wiki.num_pages
+... 6
+
+
+Property-12: **count** -- *int total number of items on the cursor*
+
+>>> paged_wiki.count
+... 55
+
+It's same as that of ``total_wikis.count()``