Grid

py4web comes with a Grid object providing simple grid and CRUD capabilities.

Key Features

  • Click column heads for sorting - click again for DESC

  • Pagination control

  • Built in Search (can use search_queries OR search_form)

  • Action Buttons - with or without text

  • Full CRUD with Delete Confirmation

  • Pre and Post Action (add your own buttons to each row)

  • Grid dates in local format

  • Default formatting by type plus user overrides

Basic Example

In this simple example we will make a grid over the company table.

controllers.py

from functools import reduce
from py4web.utils.grid import Grid
from py4web import action
from .common import db, session, auth

@action('companies', method=['POST', 'GET'])
@action('companies/<path:path>', method=['POST', 'GET'])
@action.uses(session, db, auth, 'grid.html')
def companies(path=None):
    grid = Grid(path,
                query=reduce(lambda a, b: (a & b), [db.company.id > 0]),
                orderby=[db.company.name],
                search_queries=[['Search by Name', lambda val: db.company.name.contains(val)]])

    return dict(grid=grid)

grid.html

[[extend 'layout.html']]
[[=grid.render()]]

Signature

class Grid:
    def __init__(
        self,
        path,
        query,
        search_form=None,
        search_queries=None,
        fields=None,
        show_id=False,
        orderby=None,
        left=None,
        headings=None,
        create=True,
        details=True,
        editable=True,
        deletable=True,
        pre_action_buttons=None,
        post_action_buttons=None,
        auto_process=True,
        rows_per_page=15,
        include_action_button_text=True,
        search_button_text="Filter",
        formstyle=FormStyleDefault,
        grid_class_style=GridClassStyle,
    ):
  • path: the route of this request

  • query: pydal query to be processed

  • search_form: py4web FORM to be included as the search form. If search_form is passed in then the developer is responsible for applying the filter to the query passed in. This differs from search_queries.

  • search_queries: list of query lists to use to build the search form. Ignored if search_form is used. Format is

  • fields: list of fields to display on the list page, if blank, glean tablename from first query and use all fields of that table

  • show_id: show the record id field on list page - default = False

  • orderby: pydal orderby field or list of fields

  • left: if joining other tables, specify the pydal left expression here

  • headings: list of headings to be used for list page - if not provided use the field label

  • details: URL to redirect to for displaying records - set to True to automatically generate the URL - set to False to not display the button

  • create: URL to redirect to for creating records - set to True to automatically generate the URL - set to False to not display the button

  • editable: URL to redirect to for editing records - set to True to automatically generate the URL - set to False to not display the button

  • deletable: URL to redirect to for deleting records - set to True to automatically generate the URL - set to False to not display the button

  • pre_action_buttons: list of action_button instances to include before the standard action buttons

  • post_action_buttons: list of action_button instances to include after the standard action buttons

  • auto_process: Boolean - whether or not the grid should be processed immediately. If False, developer must call grid.process() once all params are setup

  • rows_per_page: number of rows to display per page. Default 15

  • include_action_button_text: boolean telling the grid whether or not you want text on action buttons within your grid

  • search_button_text: text to appear on the submit button on your search form

  • formstyle: py4web Form formstyle used to style your form when automatically building CRUD forms

  • grid_class_style: GridClassStyle object used to override defaults for styling your rendered grid. Allows you to specify classes or styles to apply at certain points in the grid.

Searching / Filtering

There are two ways to build a search form.

  • Provide a search_queries list

  • Build your own custom search form

If you provide a search_queries list to grid, it will:

  • build a search form. If more than one search query in the list, it will also generate a dropdown to select which search field to search against

  • gather filter values and filter the grid

However, if this doesn’t give you enough flexibility you can provide your own search form and handle all the filtering (building the queries) by yourself.

CRUD

The grid provides CRUD (create, read, update and delete) capabilities utilizing py4web Form.

You can turn off CRUD features by setting create/details/editable/deletable during grid instantiation.

Additionally, you can provide a separate URL to the create/details/editable/deletable parameters to bypass the auto-generated CRUD pages and handle the detail pages yourself.

Using templates

Use the following to render your grid or CRUD forms in your templates.

Display the grid or a CRUD Form

[[=grid.render()]]

To allow for customizing CRUD form layout (like with web2py) you can use the following

[[form = grid.render() ]]
[[form.custom["begin"] ]]
...
[[form.custom["submit"]
[[form.custom["end"]

When handling custom form layouts you need to know if you are displaying the grid or a form. Use the following to decide

[[if request.query.get('action') in ('details', 'edit'):]]
    #  Display the custom form
    [[form = grid.render() ]]
    [[form.custom["begin"] ]]
    ...
    [[form.custom["submit"]
    [[form.custom["end"]
[[else:]]
    [[grid.render() ]]
[[pass]]

Customizing Style

You can provide your own formstyle or grid classes and style to grid.

  • formstyle is the same as a Form formstyle, used to style the CRUD forms.

  • grid_class_style is a class that provides the classes and/or styles used for certain portions of the grid.

The default GridClassStyle - based on no.css, primarily uses styles to modify the layout of the grid

class GridClassStyle:

    """
    Default grid style
    Internal element names match default class name, other classes can be added
    Style use should be minimized since it cannot be overridden by CSS
    """

    classes = {
        "grid-wrapper": "grid-wrapper",
        "grid-header": "grid-header",
        "grid-new-button": "grid-new-button info",
        "grid-search": "grid-search",
        "grid-table-wrapper": "grid-table-wrapper",
        "grid-table": "grid-table",
        "grid-sorter-icon-up": "grid-sort-icon-up fas fa-sort-up",
        "grid-sorter-icon-down": "grid-sort-icon-down fas fa-sort-down",
        "grid-th-action-button": "grid-col-action-button",
        "grid-td-action-button": "grid-col-action-button",
        "grid-tr": "",
        "grid-th": "",
        "grid-td": "",
        "grid-details-button": "grid-details-button info",
        "grid-edit-button": "grid-edit-button info",
        "grid-delete-button": "grid-delete-button info",
        "grid-footer": "grid-footer",
        "grid-info": "grid-info",
        "grid-pagination": "grid-pagination",
        "grid-pagination-button": "grid-pagination-button info",
        "grid-pagination-button-current": "grid-pagination-button-current default",
        "grid-cell-type-string": "grid-cell-type-string",
        "grid-cell-type-text": "grid-cell-type-text",
        "grid-cell-type-boolean": "grid-cell-type-boolean",
        "grid-cell-type-float": "grid-cell-type-float",
        "grid-cell-type-int": "grid-cell-type-int",
        "grid-cell-type-date": "grid-cell-type-date",
        "grid-cell-type-time": "grid-cell-type-time",
        "grid-cell-type-datetime": "grid-cell-type-datetime",
        "grid-cell-type-upload": "grid-cell-type-upload",
        "grid-cell-type-list": "grid-cell-type-list",
        # specific for custom form
        "search_form": "search-form",
        "search_form_table": "search-form-table",
        "search_form_tr": "search-form-tr",
        "search_form_td": "search-form-td",
    }

    styles = {
        "grid-wrapper": "",
        "grid-header": "display: table; width: 100%",
        "grid-new-button": "display: table-cell;",
        "grid-search": "display: table-cell; float:right",
        "grid-table-wrapper": "overflow-x: auto; width:100%",
        "grid-table": "",
        "grid-sorter-icon-up": "",
        "grid-sorter-icon-down": "",
        "grid-th-action-button": "",
        "grid-td-action-button": "",
        "grid-tr": "",
        "grid-th": "white-space: nowrap; vertical-align: middle",
        "grid-td": "white-space: nowrap; vertical-align: middle",
        "grid-details-button": "margin-bottom: 0",
        "grid-edit-button": "margin-bottom: 0",
        "grid-delete-button": "margin-bottom: 0",
        "grid-footer": "display: table; width:100%",
        "grid-info": "display: table-cell;",
        "grid-pagination": "display: table-cell; text-align:right",
        "grid-pagination-button": "min-width: 20px",
        "grid-pagination-button-current": "min-width: 20px; pointer-events:none; opacity: 0.7",
        "grid-cell-type-string": "white-space: nowrap; vertical-align: middle; text-align: left; text-overflow: ellipsis; max-width: 200px",
        "grid-cell-type-text": "vertical-align: middle; text-align: left; text-overflow: ellipsis; max-width: 200px",
        "grid-cell-type-boolean": "white-space: nowrap; vertical-align: middle; text-align: center",
        "grid-cell-type-float": "white-space: nowrap; vertical-align: middle; text-align: right",
        "grid-cell-type-int": "white-space: nowrap; vertical-align: middle; text-align: right",
        "grid-cell-type-date": "white-space: nowrap; vertical-align: middle; text-align: right",
        "grid-cell-type-time": "white-space: nowrap; vertical-align: middle; text-align: right",
        "grid-cell-type-datetime": "white-space: nowrap; vertical-align: middle; text-align: right",
        "grid-cell-type-upload": "white-space: nowrap; vertical-align: middle; text-align: center",
        "grid-cell-type-list": "white-space: nowrap; vertical-align: middle; text-align: left",
        # specific for custom form
        "search_form": "",
        "search_form_table": "",
        "search_form_tr": "",
        "search_form_td": "",
    }

    @classmethod
    def get(cls, element):
        """returns a dict with _class and _style for the element name"""
        return {
            "_class": cls.classes.get(element),
            "_style": cls.styles.get(element),
        }

GridClassStyleBulma - bulma implementation

class GridClassStyleBulma(GridClassStyle):
    classes = {
        "grid-wrapper": "grid-wrapper field",
        "grid-header": "grid-header pb-2",
        "grid-new-button": "grid-new-button button",
        "grid-search": "grid-search is-pulled-right pb-2",
        "grid-table-wrapper": "grid-table-wrapper table_wrapper",
        "grid-table": "grid-table table is-bordered is-striped is-hoverable is-fullwidth",
        "grid-sorter-icon-up": "grid-sort-icon-up fas fa-sort-up is-pulled-right",
        "grid-sorter-icon-down": "grid-sort-icon-down fas fa-sort-down is-pulled-right",
        "grid-th-action-button": "grid-col-action-button is-narrow",
        "grid-td-action-button": "grid-col-action-button is-narrow",
        "grid-tr": "",
        "grid-th": "",
        "grid-td": "",
        "grid-details-button": "grid-details-button button is-small",
        "grid-edit-button": "grid-edit-button button is-small",
        "grid-delete-button": "grid-delete-button button is-small",
        "grid-footer": "grid-footer",
        "grid-info": "grid-info is-pulled-left",
        "grid-pagination": "grid-pagination is-pulled-right",
        "grid-pagination-button": "grid-pagination-button button is-small",
        "grid-pagination-button-current": "grid-pagination-button-current button is-primary is-small",
        "grid-cell-type-string": "grid-cell-type-string",
        "grid-cell-type-text": "grid-cell-type-text",
        "grid-cell-type-boolean": "grid-cell-type-boolean has-text-centered",
        "grid-cell-type-float": "grid-cell-type-float",
        "grid-cell-type-int": "grid-cell-type-int",
        "grid-cell-type-date": "grid-cell-type-date",
        "grid-cell-type-time": "grid-cell-type-time",
        "grid-cell-type-datetime": "grid-cell-type-datetime",
        "grid-cell-type-upload": "grid-cell-type-upload",
        "grid-cell-type-list": "grid-cell-type-list",
        # specific for custom form
        "search_form": "search-form is-pulled-right pb-2",
        "search_form_table": "search-form-table",
        "search_form_tr": "search-form-tr",
        "search_form_td": "search-form-td pr-1",
    }

    styles = {
        "grid-wrapper": "",
        "grid-header": "",
        "grid-new-button": "",
        "grid-search": "",
        "grid-table-wrapper": "",
        "grid-table": "",
        "grid-sorter-icon-up": "",
        "grid-sorter-icon-down": "",
        "grid-th-action-button": "",
        "grid-td-action-button": "",
        "grid-tr": "",
        "grid-th": "text-align: center; text-transform: uppercase;",
        "grid-td": "",
        "grid-details-button": "",
        "grid-edit-button": "",
        "grid-delete-button": "",
        "grid-footer": "padding-top: .5em;",
        "grid-info": "",
        "grid-pagination": "",
        "grid-pagination-button": "margin-left: .25em;",
        "grid-pagination-button-current": "margin-left: .25em;",
        "grid-cell-type-string": "",
        "grid-cell-type-text": "",
        "grid-cell-type-boolean": "",
        "grid-cell-type-float": "",
        "grid-cell-type-int": "",
        "grid-cell-type-date": "",
        "grid-cell-type-time": "",
        "grid-cell-type-datetime": "",
        "grid-cell-type-upload": "",
        "grid-cell-type-list": "",
        # specific for custom form
        "search_form": "",
        "search_form_table": "",
        "search_form_tr": "",
        "search_form_td": "",
    }

You can build your own class_style to be used with the css framework of your choice.

Custom Action Buttons

As with web2py, you can add additional buttons to each row in your grid. You do this by providing pre_action_buttons or post_action_buttons to the Grid init method.

  • pre_action_buttons - list of action_button instances to include before the standard action buttons

  • post_action_buttons - list of action_button instances to include after the standard action buttons

You can build your own Action Button class to pass to pre/post action buttons based on the template below (this is not provided with py4web)

Sample Action Button Class

def __init__(self,
             url,
             text,
             icon="fa-calendar",
             additional_classes=None,
             message=None,
             append_id=False):
  • url: the page to navigate to when the button is clicked

  • text: text to display on the button

  • icon: the font-awesome icon to display before the text

  • additional_classes: a space-separated list of classes to include on the button element

  • message: confirmation message to display if ‘confirmation’ class is added to additional classes

  • append_id: if True, add id_field_name=id_value to the url querystring for the button

Reference Fields

When displaying fields in a PyDAL table, you sometimes want to display a more descriptive field than a foreign key value. There are a couple of ways to handle that with the py4web grid.

filter_out on PyDAL field definition - here is an example of a foreign key field

Field('company', 'reference company',
      requires=IS_NULL_OR(IS_IN_DB(db, 'company.id',
                                   '%(name)s',
                                   zero='..')),
      filter_out=lambda x: x.name if x else ''),

This will display the company name in the grid instead of the company ID

The downfall of using this method is that sorting and filtering are based on the company field in the employee table and not the name of the company

left join and specify fields from joined table - specified on the left parameter of Grid instantiation

db.company.on(db.employee.company == db.company.id)

You can specify a standard PyDAL left join, including a list of joins to consider.

Now the company name field can be included in your fields list can be clicked on and sorted.

Now you can also specify a query such as:

queries.append((db.employee.last_name.contains(search_text)) | (db.employee.first_name.contains(search_text)) | db.company.name.contains(search_text)))

This method allows you to sort and filter, but doesn’t allow you to combine fields to be displayed together as the filter_out method would

You need to determine which method is best for your use case understanding the different grids in the same application may need to behave differently.