# query.FilterExpressionError

- **Module:** query
- **Package:** libtmux
- **Language:** Rust
- **Kind:** struct
- **Source:** https://github.com/libtmux/libtmux-rs/blob/f0e37052c232636b61d095817046e6bfc8f2ca40/crates/libtmux/src/query.rs#L671
- **Page:** https://libtmux.org/en/rs/latest/reference/query-filterexpressionerror/

A source-less, value-free portable expression validation error.

The error retains only its category. In particular, it never retains a
regex pattern, field literal, or rejected serialized value.

## Example

```rust
use libtmux::query::{FilterExpressionErrorKind, TextField};
use libtmux::query::__private;

struct Row;
let field: TextField<Row> = __private::text_field("row", "name");
let error = field.regex("[").expect_err("the pattern is invalid");
assert_eq!(error.kind(), FilterExpressionErrorKind::InvalidRegex);
```

## Members

- `kind` (method): Return the value-free validation category.