CollectionFilter

A class which encapsulates a single filter operation which may be applied to any object to decide whether to include or exclude it from a set.

A CollectionFilter generally has at least three main properties:

• property - The name of a property in candidate objects from which to extract the value to test
• value - The value which this filter uses to test against.
• operator - The comparison operator, eg: '=' or '>' etc.

Given these three essential values, further configurations may affect how the filter is applied:

• caseSensitive - If configured as false, string comparisons are case insensitive.
• convert - A function which, when passed the extracted value from the candidate object, returns the value to test.

A filter may also be configured with a single filterBy property. This function is just passed the raw candidate object and must return true or false.

A CollectionFilter may be configured to encapsulate a single filtering function by passing that function as the sole parameter to the constructor:

new CollectionFilter(candidate => candidate.title.contains('search string'));

Logical Operators

A CollectionFilter may instead be configured with a children property, which is an array of other CollectionFilters. If this is configured, the operator property must be set to either 'and' or 'or'. The children filters are then combined with the parent filter using the specified operator:

// A filter which matches any candidate object which has a duration greater than 10 or a priority of 'high'
// This is equivalent to the SQL expression: `duration > 10 OR priority = 'high'`
new CollectionFilter({
    operator : 'or',
    children : [
        { property : 'duration', operator : '>', value : 10 },
        { property : 'priority', operator : '=', value : 'high' }
    ]
});

Or, for nested filters which require parentheses:

// A filter which matches any candidates who are in Paris and are either under 18 or over 70
// This is equivalent to the SQL expression: `city = 'Paris' AND (age < 18 OR age > 70)`
new CollectionFilter({
    operator : 'and',
    children : [
        { property : 'city', operator : '=', value : 'Paris },
        {
            operator : 'or',
            children : [
                { property : 'age', operator : '<', value : 18 },
                { property : 'age', operator : '>', value : 70 }
            ]
        }
    ]
});