# `Cinder.Filters.MultiSelect`
[🔗](https://github.com/sevenseacat/cinder/blob/v0.18.0/lib/cinder/filters/multi_select.ex#L5)

Multi-select filter: a dropdown of checkboxes for choosing any number of values, showing how
many are chosen. Takes `options` (`{label, value}` tuples), `match_mode`, and `prompt` (the
dropdown's text when nothing is chosen).

## Values from the client

Selections arrive from the browser (the URL, or the form), so they're trimmed before
they reach the query: duplicates are dropped, and only values among the filter's
`options` are kept when it has any. Without options, at most 100 values are kept.

## Match Mode Options

The `match_mode` option controls how multiple selections are combined:

- `:any` (default) - Shows records containing ANY of the selected values (OR logic)
- `:all` - Shows records containing ALL of the selected values (AND logic)

## Examples

    # ANY logic - show books with at least one selected tag
    <:col
      field="tags"
      filter={[type: :multi_select, options: [{"Fiction", "fiction"}, {"Romance", "romance"}]]}
    />

    # ALL logic - show books that have all selected tags
    <:col
      field="tags"
      filter={[
        type: :multi_select,
        options: [{"Fiction", "fiction"}, {"Bestseller", "bestseller"}],
        match_mode: :all
      ]}
    />

## Array Fields

On an array field (an array attribute, a `list` aggregate or an array calculation), a
record matches when its array holds the selected values. Through a to-many relationship
(`albums.tags`, `albums.genre`), `:all` means the related records hold every value between
them. On a plain field of the record itself, `match_mode` has no effect: a record matches
any of the values.

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*Consult [api-reference.md](api-reference.md) for complete listing*