# `QuackDB.Ecto.Variant`
[🔗](https://github.com/elixir-vibe/quackdb/blob/main/lib/quack_db/ecto/variant.ex#L2)

DuckDB 2.0 `VARIANT` expression helpers for Ecto queries.

VARIANT columns decode to Elixir terms: objects become maps with string
keys, arrays become lists, and scalars decode like the matching column type.
These helpers inspect and extract inside a VARIANT on the server:

    import Ecto.Query
    import QuackDB.Ecto.Variant

    from event in "events",
      where: variant_type(event.payload) == "OBJECT",
      select: %{
        kind: variant_extract_string(event.payload, "kind"),
        first_tag: variant_extract(event.payload, [:tags, 1]),
        keys: variant_keys(event.payload)
      }

A key is a field name; an integer extracts from an array, counting from 1.
A list such as `[:tags, 1]` extracts one step at a time.

# `variant_array_length`
*macro* 

Builds `variant_array_length(variant)`, or `variant_array_length(variant, key)`.

# `variant_array_length`
*macro* 

# `variant_contains`
*macro* 

Builds `variant_contains(haystack, needle)`; the needle is cast to VARIANT.

# `variant_extract`
*macro* 

Builds `variant_extract(variant, key)`, which returns a VARIANT. Pass a list
to extract along a path.

# `variant_extract_string`
*macro* 

Builds `variant_extract_string(variant, key)`, the field rendered as text.

# `variant_keys`
*macro* 

Builds `variant_keys(variant)`, or `variant_keys(variant, key)` for a nested object.

# `variant_keys`
*macro* 

# `variant_type`
*macro* 

Builds `variant_type(variant)`, the VARIANT type name such as `"OBJECT"`,
`"ARRAY"`, or `"INT64"`, or `variant_type(variant, key)` for a field.

# `variant_type`
*macro* 

# `variant_typeof`
*macro* 

Builds `variant_typeof(variant)`, the DuckDB type the value would have unwrapped.

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