# query.ExactlyOneError

- **Module:** query
- **Package:** libtmux
- **Language:** Rust
- **Kind:** enum
- **Source:** https://github.com/libtmux/libtmux-rs/blob/f0e37052c232636b61d095817046e6bfc8f2ca40/crates/libtmux/src/query.rs#L450
- **Page:** https://libtmux.org/en/rs/latest/reference/query-exactlyoneerror/

The ways an iterator can fail to contain exactly one item.

## Example

```rust
use libtmux::query::{ExactlyOneError, QueryIteratorExt};

let values: Vec<i32> = Vec::new();
assert_eq!(values.iter().exactly_one(), Err(ExactlyOneError::NoItems));
```

## Members

- `NoItems` (constant): The iterator contained no items.
- `MultipleItems` (constant): The iterator contained more than one item.