# 🚧 Error Reporting
Valida provides a powerful and flexible error reporting system that separates **validation failures** from **system-level errors**. Errors are structured, deeply nestable, serializable, and localization-ready (when i18n is enabled).
---
## 🔍 Core Types
### `ValidationError`
Represents a single error leaf. Includes:
- `key: String` — the error code or i18n key
- `params: HashMap<String, String>` — optional arguments for localized message interpolation
Create errors with:
```rust
ValidationError::new("email.invalid")
ValidationError::new_with_params("validator.max_length", {
"max" => "100"
})
```
---
### ValidationNode
Used internally to represent a tree of nested errors:
```rust
enum ValidationNode {
Leaf(ValidationError),
Branch(HashMap<String, ValidationNode>)
}
```
---
### ValidationErrors
The top-level container used throughout Valida:
* Stores errors as a tree keyed by field path
* Can add errors manually (`add(...)`) or aggregate nested errors (`add_nested(...)`)
* Implements `Error + Display`
---
# 📦 Formatting Output
Valida offers multiple error formats for UI and debugging.
## 🔡 Raw Pretty Print
```rust
println!("{}", errors.pretty_print_raw())
```
Outputs a tree-like view:
```yaml
email: email.invalid
profile:
age: age.too_young
device:
name: validator.min_length
```
---
## 🔢 JSON (Raw Structure)
```rust
let json = errors.to_json_raw();
```
Includes both key and params:
```json
{
"email": {
"key": "email.invalid",
"params": {}
},
"profile": {
"age": {
"key": "age.too_young",
"params": {}
}
}
}
```
---
## 🧾 Flat HTML Form Style
```rust
let form = errors.to_json_form_raw();
```
Produces flat keys like `field[subfield]`:
```json
{
"profile[device][name]": {
"key": "validator.min_length",
"params": {}
}
}
```
Perfect for HTML-based form rendering.
---
## 🕸 Dotted Path Style
```rust
let dot = errors.to_json_dot_raw();
```
Useful for config files or path mapping:
```json
{
"profile.device.name": {
"key": "validator.min_length",
"params": {}
}
}
```
---
# 🌍 Localized Formats (Optional)
When compiled with `i18n-localization` feature, Valida supports:
* pretty_print(locale)
* to_json(locale)
* to_json_form(locale)
* to_json_dot(locale)
Localization is powered by `rust-i18n`
---
# 🧠 Best Practices
Prefer using `new_with_params(...)` for dynamic error content
Use error keys that map directly to translation files (`validator.min_length`, etc.)
Nest errors via `nested(...)` for multi-layered DTOs