# query.FilterExpressionError.kind

- **Module:** query.FilterExpressionError
- **Package:** libtmux
- **Language:** Rust
- **Kind:** method
- **Source:** https://github.com/libtmux/libtmux-rs/blob/f0e37052c232636b61d095817046e6bfc8f2ca40/crates/libtmux/src/query.rs#L692
- **Page:** https://libtmux.org/en/rs/latest/reference/query-filterexpressionerror-kind/

```
query.FilterExpressionError.kind(self) -> FilterExpressionErrorKind
```

Return the value-free validation category.

## Example

```rust
use libtmux::query::FilterExpressionErrorKind;
use libtmux::query::__private;

let error = __private::unknown_field_error();
assert_eq!(error.kind(), FilterExpressionErrorKind::UnknownField);
```