webhelpers.html.grid

A helper to make an HTML table from a list of dicts, objects, or sequences.

A set of CSS styles complementing this helper is in “webhelpers/html/public/stylesheets/grid.css”. To use them, include the stylesheet in your applcation and set your <table> class to “stylized”.

The documentation below is not very clear. This is a known bug. We need a native English speaker who uses the module to volunteer to rewrite it.

This module is written and maintained by Ergo^.

A demo is available. Run the following command to produce some HTML tables:

python -m webhelpers.html.grid_demo OUTPUT_DIR

A subclass specialized for Pylons is in webhelpers.pylonslib.grid.

Grid class

class webhelpers.html.grid.Grid(itemlist, columns, column_labels=None, column_formats=None, start_number=1, order_column=None, order_direction=None, request=None, url=None, **kw)

This class is designed to aid programmer in the task of creation of tables/grids - structures that are mostly built from datasets.

To create a grid at minimum one one needs to pass a dataset, like a list of dictionaries, or sqlalchemy proxy or query object:

grid = Grid(itemlist, ['_numbered','c1', 'c2','c4'])

where itemlist in this simple scenario is a list of dicts:

[{‘c1’:1,’c2’...}, {‘c1’...}, ...]

This helper also received the list that defines order in which columns will be rendered - also keep note of special column name that can be passed in list that defines order - _numbered - this adds additional column that shows the number of item. For paging sql data there one can pass start_number argument to the grid to define where to start counting. Descendant sorting on _numbered column decrements the value, you can change how numberign function behaves by overloading calc_row_no property.

Converting the grid to a string renders the table rows. That’s just the <tr> tags, not the <table> around them. The part outside the <tr>s have too many variations for us to render it. In many template systems, you can simply assign the grid to a template variable and it will be automatically converted to a string. Example using a Mako template:

<table class="stylized">
<caption>My Lovely Grid</caption>
<col class="c1" />
${my_grid}
</table>

The names of the columns will get automatically converted for humans ie. foo_bar becomes Foo Bar. If you want the title to be something else you can change the grid.labels dict. If you want the column part_no to become Catalogue Number just do:

grid.labels[``part_no``] = u'Catalogue Number'

It may be desired to exclude some or all columns from generation sorting urls (used by subclasses that are sorting aware). You can use grids exclude_ordering property to pass list of columns that should not support sorting. By default sorting is disabled - this exclude_ordering contains every column name.

Since various programmers have different needs, Grid is highly customizable. By default grid attempts to read the value from dict directly by key. For every column it will try to output value of current_row[‘colname’].

Since very often this behavior needs to be overridden like we need date formatted, use conditionals or generate a link one can use the column_formats dict and pass a rendering function/lambda to it. For example we want to apppend foo to part number:

def custem_part_no_td(col_num, i, item):
    return HTML.td(`Foo %s` % item[``part_no``])

grid.column_formats[``part_no``] = custem_part_no_td

You can customize the grids look and behavior by overloading grids instance render functions:

grid.default_column_format(self, column_number, i, record, column_name)
by default generates markup like:
<td class="cNO">VALUE</td>

grid.default_header_column_format(self, column_number, column_name, 
    header_label)
by default generates markup like:
<td class="cNO COLUMN_NAME">VALUE</td>
    
grid.default_header_ordered_column_format(self, column_number, order, 
    column_name, header_label)
Used by grids that support ordering of columns in the grid like, 
webhelpers.pylonslib.grid.GridPylons.
by default generates markup like:
<td class="cNO ordering ORDER_DIRECTION COLUMN_NAME">LABEL</td>

grid.default_header_record_format(self, headers)
by default generates markup like:
<tr class="header">HEADERS_MARKUP</tr>

grid.default_record_format(self, i, record, columns)
Make an HTML table from a list of objects, and soon a list of
sequences, a list of dicts, and a single dict. 
<tr class="ODD_OR_EVEN">RECORD_MARKUP</tr>

grid.generate_header_link(self, column_number, column, label_text)
by default just sets the order direction and column properties for grid.
Actual link generation is handled by sublasses of Grid.

grid.numbered_column_format(self, column_number, i, record)
by default generates markup like:
<td class="cNO">RECORD_NO</td>

This handles generation of link and then decides to call self.default_header_ordered_column_format or self.default_header_column_format based on whether current column is the one that is used for sorting.

you need to extend Grid class and overload this method implementing ordering here, whole operation consists of setting self.order_column and self.order_dir to their CURRENT values, and generating new urls for state that header should set set after its clicked

(additional kw are passed to url gen. - like for webhelpers.paginate) example URL generation code below:

GET = dict(self.request.copy().GET) # needs dict() for py2.5 compat
self.order_column = GET.pop("order_col", None)
self.order_dir = GET.pop("order_dir", None)       
# determine new order
if column == self.order_column and self.order_dir == "asc":
    new_order_dir = "dsc"
else:
    new_order_dir = "asc"
self.additional_kw['order_col'] = column
self.additional_kw['order_dir'] = new_order_dir  
# generate new url for example url_generator uses 
# pylons's url.current() or pyramid's current_route_url()
new_url = self.url_generator(**self.additional_kw)
# set label for header with link
label_text = HTML.tag("a", href=new_url, c=label_text)
class webhelpers.html.grid.ObjectGrid(itemlist, columns, column_labels=None, column_formats=None, start_number=1, order_column=None, order_direction=None, request=None, url=None, **kw)

A grid class for a sequence of objects.

This grid class assumes that the rows are objects rather than dicts, and uses attribute access to retrieve the column values. It works well with SQLAlchemy ORM instances.

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