Macro field_err 

macro_rules! field_err {
    ($code:literal) => { ... };
    ($code:literal, $message:literal) => { ... };
    ($code:literal, $message:literal, $field:literal) => { ... };
}

Creates a new field validation error. Serves as a shorthand for writing out errors for custom functions and schema validations. Accepts:

• ("code")
• ("code", "message")
• ("field_name", "code", "message")

 use validify::field_err;

 let err = field_err!("foo");
 assert_eq!(err.code(), "foo");
 assert_eq!(err.location(), "");
 assert!(err.message().is_none());
 assert!(err.field_name().is_none());

 let err = field_err!("foo", "bar");
 assert_eq!(err.code(), "foo");
 assert_eq!(err.location(), "");
 assert_eq!(err.message().unwrap(), "bar");
 assert!(err.field_name().is_none());

 let err = field_err!("foo", "bar", "field");
 assert_eq!(err.code(), "foo");
 assert_eq!(err.message().unwrap(), "bar");
 assert_eq!(err.field_name().unwrap(), "field");
 assert_eq!(err.location(), "/field");