String validator

The ValidatorString provides functions for setting validation rules for a string type value, or a custom type based on a string.

Below is a valid example for every String validator rule.

v.Is(v.String("Dennis Ritchie").EqualTo("Dennis Ritchie"))
v.Is(v.String("Steve Jobs").GreaterThan("Bill Gates"))
v.Is(v.String("Steve Jobs").GreaterOrEqualTo("Elon Musk"))
v.Is(v.String("C#").LessThan("Go"))
v.Is(v.String("Go").LessOrEqualTo("Golang"))
v.Is(v.String("Rust").Between("Go", "Typescript")) // Inclusive
v.Is(v.String("").Empty())
v.Is(v.String(" ").Blank())
v.Is(v.String("Dart").Passing(func(val string) bool { return val == "Dart" }))
v.Is(v.String("processing").InSlice([]string{"idle", "processing", "ready"})
v.Is(v.String("123456").MaxLength(6))
v.Is(v.String("123").MinLength(3))
v.Is(v.String("1234").MinLength(4))
v.Is(v.String("12345").LengthBetween(4,6)) // Inclusive
regex, _ := regexp.Compile("pre-.+"); v.Is(String("pre-approved").MatchingTo(regex))