sebastienros / fluid

When using the where filter with a single argument, the filter does not perform truthy comparisons. The equality comparison is performed with the property value controlling.

fluid/Fluid/Filters/ArrayFilters.cs

Line 156 in 74cb742

if (itemValue.Equals(targetValue))

Switching itemValue and targetValue, such that targetValue is controlling would result in truthy comparisons.

Here's a workaround with adding a new filter named twhere

Usage twhere instead of where:

{% assign filteredItems = items | twhere: "property" %}

Register in the filters:

builder.AddFluid(x => {
    x.TemplateOptions.Filters.AddFilter(WhereFilter.Name, WhereFilter.Where);
});

Filter implementation with workaround:

internal static class WhereFilter
{
    internal const string Name = "twhere";

    // Track issue: https://github.com/sebastienros/fluid/issues/620
    internal static async ValueTask<FluidValue> Where(FluidValue input, FilterArguments arguments, TemplateContext context)
    {
        if (input.Type != FluidValues.Array)
        {
            return input;
        }

        // First argument is the property name to match
        var member = arguments.At(0).ToStringValue();

        // Second argument is the value to match, or 'true' if none is defined
        var targetValue = arguments.At(1).Or(BooleanValue.True);

        var list = new List<FluidValue>();

        foreach (var item in input.Enumerate(context))
        {
            var itemValue = await item.GetValueAsync(member, context);

            if (itemValue.Equals(targetValue) ||
                // Issue workaround for equality inconsistencies: to check if the other equals self
                targetValue.Equals(itemValue))
            {
                list.Add(item);
            }
        }

        return new ArrayValue(list);
    }
}

So instead of comparing to true we actually need to handle the single argument separately and convert it using ToBooleanValue(). Can someone create a PR and a test for that?

Where filter does not handle truthy values correctly