Filter Presets

Backpex allows you to define filter presets for your filters. Filter presets are used to define a set of filter configurations that can easily be applied to the data being displayed in the index view. Filter Presets consist of a name and a list of values that are used to filter the data. For example, you can define a filter preset for a date filter that filters the data based on the current month. Then the user can easily apply this filter by selecting the preset from the filter dropdown.

Defining a Filter Preset

To define presets for your filters, you need to add a list of maps under the key of :presets to your filter in your LiveResource.

Each of those maps has two keys:

1. :label – the name of the preset shown to the user
2. :values – a function with arity 0 that returns the values corresponding to your used filter

See the example below for some preset examples. We add a preset for a date filter that filters the data based on the last 7 days and a preset for a select filter that filters the data based on the published status of an event.

@impl Backpex.LiveResource
def filters, do: [
  begins_at: %{
    module: MyAppWeb.Filters.DateRange,
    label: "Begins At",
    presets: [
      %{
        label: "Last 7 Days",
        values: fn -> %{
          "start" => Date.add(Date.utc_today(), -7),
          "end" => Date.utc_today()
        } end
      }
    ]
  },
  published: %{
    module: MyAppWeb.Filters.EventPublished,
    presets: [
      %{
        label: "Both",
        values: fn -> [:published, :not_published] end
      },
      %{
        label: "Only published",
        values: fn -> [:published] end
      }
    ]
  }
]

Preset Validation

Preset values go through the same validation as manually entered filter values. This means:

• Values are cast to the appropriate type based on the filter's type/1 callback
• Custom validations from changeset/3 are applied
• Invalid preset values will not be applied to the query

When defining presets, ensure the values match the expected format for your filter type:

Related Guides

• Filter Validation - Comprehensive validation documentation
• What is a Filter? - Overview of the filter system
• How to Add a Filter - Adding filters to your LiveResource