---
title: validate_backend
summary: Validate that a string looks like an acceptable Backend value.
url: https://www.fastly.com/documentation/reference/compute/sdks/rust/fastly/backend/fn.validate_backend/
---

**Kind:** Function  
**Module:** [backend](https://www.fastly.com/documentation/reference/compute/sdks/rust/fastly/backend/)  
**Package:** fastly 0.13.1  
**Source:** https://docs.rs/crate/fastly/0.13.1/source/src/backend.rs#828

```rust
fn validate_backend(backend: &str) -> Result<(), BackendError>
```

Validate that a string looks like an acceptable [`Backend`](https://www.fastly.com/documentation/reference/compute/sdks/rust/fastly/backend/struct.Backend/) value.

Note that this is *not* meant to be a filter for things that could cause security issues, it is
only meant to catch errors before the hostcalls do in order to yield friendlier error messages.

This function will return a [`BackendError`](https://www.fastly.com/documentation/reference/compute/sdks/rust/fastly/backend/enum.BackendError/) if an invalid name was given.

Backend names:
  * cannot be empty
  * cannot be longer than 255 characters
  * cannot ASCII control characters such as `'\n'` or `DELETE`.
  * cannot contain special Unicode characters
  * should only contain visible ASCII characters or spaces

**Parameters**

- `backend`: `&str`

**Returns**

`Result<(), BackendError>`