[Table] MatTableDataSource does not execute filter predicate if filter evaluates to false

Bug, feature request, or proposal:

Bug

What is the expected behavior?

Filter text should not be required for using a filter when a custom filterPredicate is supplied

What is the current behavior?

Filter text must be truthy in order to use a filterPredicate which does not require filter text

What are the steps to reproduce?

Make a filterPredicate which does not depend on the filter value

What is the use-case or motivation for changing an existing behavior?

Filter predicates which do not require the filter text (for example, checking that a value in the data is past the current date)

Which versions of Angular, Material, OS, TypeScript, browsers are affected?

Current

Is there anything else we should know?

https://github.com/angular/material2/blob/master/src/lib/table/table-data-source.ts#L213 !this.filter ? data : data.filter(obj => this.filterPredicate(obj, this.filter)); Instead of !this.filter ? check if a filterPredicate has been supplied

[RomainSanchez]

@Eddygn

when making a custom predicate, if it’s not dependent on the filter string but instead on external flags and the row data, there is no way to trigger the filter itself except to pass some new string to the filter text, even if it’s meaningless. So for now ‘stringifying’ those flags looks like the best option even if the string is not used. I think it will be great if there is a method to call to filter, bypassing the filter change detection, or triggering it manually.

i worked around it this way (ugly)

const currentFilter = this.tableDataSource.filter;

this.tableDataSource.filter = '------';
this.tableDataSource.filter = currentFilter;

[Eddygn]

Somewhat related, when making a custom predicate, if it’s not dependent on the filter string but instead on external flags and the row data, there is no way to trigger the filter itself except to pass some new string to the filter text, even if it’s meaningless. So for now ‘stringifying’ those flags looks like the best option even if the string is not used. I think it will be great if there is a method to call to filter, bypassing the filter change detection, or triggering it manually.