Custom Columns

The basic WebGrid Column is flexible enough to handle a great deal of data. With the other supplied built-in columns for specific data types (boolean, date, float/decimal, int, etc.), the most common scenarios are covered. However, any of these supplied column classes may be extended for application-specific scenarios.

Below are some examples of common customizations on grid columns.

Rendered value:

class AgeColumn(Column):
    def extract_data(self, record):
        # All rendered targets will show this output instead of the actual data value
        if record.age < 18:
            return 'Under 18'
        return 'Over 18'

Render specialized for single target:

class AgeColumn(Column):
    def render_html(self, record, hah):
        # Only the HTML output will show this instead of the actual data value.
        if record.age < 18:
            # Add a CSS class to this cell for further styling.
            hah.class_ = 'under-18'
            return 'Under 18'
        return 'Over 18'

Sorting algorithm:

class ShipmentReceived(Column):
    def apply_sort(self, query, flag_desc):
        # Always sort prioritized shipments first
        if flag_desc:
            return query.order_by(
                priority_col.asc(),
                self.expr.desc(),
            )
        return query.order_by(
            priority_col.asc(),
            self.expr.asc(),
        )

XLSX formula:

class ConditionalFormulaColumn(Column):
    xlsx_formula = '=IF(AND(K{0}<>"",C{0}<>""),(K{0}-C{0})*24,"")'

    def render_xlsx(self, record, rownum=0):
        return self.xlsx_formula.format(rownum)

Value links to another view:

class ProjectColumn(LinkColumnBase):
    def create_url(self, record):
        return flask.url_for(
            'admin.project-view',
            objid=record.id,
        )