Angular Data Grid: Date Filter

Date filters allow you to filter date data. The Provided Filters and Simple Filters pages explain the parts of the date filter that are the same as the other provided filters. This page builds on that and explains some details that are specific to the date filter.

Date Filter Parameters

Date Filters are configured though the filterParams attribute of the column definition. All of the parameters from Provided Filters are available:

In addition, the following parameters are also available:

Date Selection Component

By default the grid will use the browser-provided date picker for Chrome and Firefox (as we think it's nice), but for all other browsers it will provide a simple text field. To override this and provide a custom date picker, see Date Component.

Date Filter Comparator

Dates can be represented in your data in many ways e.g. as a JavaScript Date object, as a string in a particular format such as '26-MAR-2020', or something else. How you represent dates will be particular to your application.

By default, the date filter assumes you are using JavaScript Date objects. If this is the case, the date filter will work out of the box. However, if your date is in any other format you will have to provide your own comparator to perform the date comparisons.

The comparator function takes two parameters. The first parameter is a JavaScript Date object for the selected date in the filter (with the time set to midnight). The second parameter is the current value of the cell in the row being evaluated. The function must return:

• Any number < 0 if the cell value is less than the filter date.
• 0 if the dates are the same.
• Any number > 0 if the cell value is greater than the filter date.

This pattern is intended to be similar to the JavaScript compareTo(a, b) function.

Below is an example of using a date filter with a comparator.

<ag-grid-angular
    [columnDefs]="columnDefs"
    /* other grid options ... */>
</ag-grid-angular>

this.columnDefs = [
    // column definition configured to use a date filter
    {
        field: 'date',
        filter: 'agDateColumnFilter',
        // add extra parameters for the date filter
        filterParams: {
            // provide comparator function
            comparator: (filterLocalDateAtMidnight, cellValue) => {
                const dateAsString = cellValue;

                if (dateAsString == null) {
                    return 0;
                }

                // In the example application, dates are stored as dd/mm/yyyy
                // We create a Date object for comparison against the filter date
                const dateParts = dateAsString.split('/');
                const day = Number(dateParts[2]);
                const month = Number(dateParts[1]) - 1;
                const year = Number(dateParts[0]);
                const cellDate = new Date(year, month, day);

                // Now that both parameters are Date objects, we can compare
                if (cellDate < filterLocalDateAtMidnight) {
                    return -1;
                } else if (cellDate > filterLocalDateAtMidnight) {
                    return 1;
                }
                return 0;
            }
        }
    }
];

Once the date comparator callback is provided, then the Date Filter is able to perform all the comparison operations it needs, e.g. 'Less Than', 'Greater Than' and 'Equals'.

Date Model vs Comparison Types

It should be noted that the Date Filter Model represents the Date as a string in format 'YYYY-MM-DD', however when doing comparisons the date is provided as a JavaScript Date object as that's what date pickers typically work with. The model uses string representation to make it easier to save and avoid any timezone issues.

Example: Date Filter

The example below shows the date filter in action, using some of the configuration options discussed above:

• The Date column is using a Date Filter.
• A custom comparator is provided to parse the data and allow date comparisons to be made.
• The native date picker is forced to be used in every browser.
• The minimum valid year is set to 2000, so dates entered into the filter with a year less than 2000 will not be recognised. This avoids the filter getting applied as the user is typing a year - for example suppose the user is typing the year "2008", the filter doesn't execute for values "2", "20" or "200" (as the text "2008" is partially typed).

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