Question 1

How to validate nested structs with ozzo-validation?

Accepted Answer

Use the Validatable interface by implementing a Validate method for nested structs, or use validation.Field within ValidateStruct. The README shows an example where Address is validated inside Customer by calling its Validate method.

Question 2

ozzo-validation vs go-playground/validator: which should I use?

Accepted Answer

ozzo-validation uses programmatic validation for clarity and maintainability, while go-playground/validator relies on struct tags for brevity. Choose ozzo if you prefer explicit Go code and flexibility, or go-playground for quick integration and less boilerplate.

Question 3

How to create a custom validation rule in ozzo-validation?

Accepted Answer

Implement the validation.Rule interface with a Validate method, or use validation.By to wrap a function. The README provides an example with stringEquals, where a closure takes parameters for reusable rules.

Question 4

Can ozzo-validation handle conditional validation based on other fields?

Accepted Answer

Yes, using the When and Else methods. The README demonstrates conditional validation, such as requiring the Unit field only when Quantity is not empty, using validation.When.

Question 5

How to return validation errors as JSON in a REST API with ozzo-validation?

Accepted Answer

Validation errors implement json.Marshaler, so you can marshal them directly to JSON. The README shows this with the Address struct, where errors are formatted based on json tags for field names.

Question 6

Is ozzo-validation good for validating maps and slices?

Accepted Answer

Yes, it supports validating maps, slices, and arrays using validation.Map or validation.Each. The README includes a map validation example with nested structures and key-specific rules.

ozzo-validation

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