govalidator
Package of validators and sanitizers for strings, numerics, etc.
...SetFieldsRequiredByDefault causes validation to fail when struct fields do not include validations or are not explicitly marked as exempt (using valid:"-" or valid:"email,optional"). A good place to activate this is a package init function or the main() function. SetNilPtrAllowedByRequired causes validation to pass when struct fields marked by required are set to nil. This is disabled by default for consistency, but some packages that need to be able to determine between nil and zero value state can use this. If disabled, both nil and zero values cause validation errors. ...