FilterRule

Define a filter predicate that will return a boolean for each item. If multiple filters are active, all filters must match for an item to be returned.

filterRule({
    id: string;
    filterFn: (item: FItem, value: FValue, meta?: FinderMeta) => boolean;
    options?: FilterOption<FValue>[] | ((items: FItem[], meta?: FinderMeta) => FilterOption<FValue>[]);
    multiple?: boolean;
    boolean?: boolean;
    required?: boolean;
    defaultValue?: FValue | FValue[];
    label?: string;
    hidden?: boolean;
    debounceMilliseconds?: number;
})

Prop	Description	Default	Required
id	Every filter rule must have a unique string id.		✓
filterFn	A predicate that returns a boolean. Note that it receives the Meta mixin, which can contain instance-wide arbitrary data.		✓
options	Either an array of form options [{label: 'Thing', value: 'thing'}], or an option generator function that returns options. (items, meta) => [{label: 'Thing', value: 'thing'}].
multiple	If this filter has a single value or an array of values.	false
required	Whether this filter must always have a value. If the rule provides options, the first option will be selected by default.	false
boolean	If this filter has a true/false value. Useful for checkboxes!	false
defaultValue	If the filter has a preset value.
label	Optional label for your client to display.
hidden	Optional display value for your client to display.	false
debounceMilliseconds	If you want to debounce value changes, enter a time in milliseconds.

tip

Don't know the exact option list in advance? Option generator functions are extremely useful!

filterRule({
    ...
    options: (items) => {
        const allCategories = items.map((item) => item.category);
        const uniqueCategories = new Set(allCategories);
        return uniqueCategories.map((category) => {
            return {
                label: capitalize(category),
                value: category
            }
        })
    }
}

If a rule uses an option generator function, Finder will hydrate the rule with a stable options array before emitting it to the client. Options will be recalculated whenever items or context are changed.