github.com/Teamwork/validate (go): Package validate provides simple validation for Go.  Basic usage example:  All validators treat the input's zero type (empty string, 0, nil, etc.) as valid. Use the Required() validator if you want to make a parameter required.  All validators optionally accept a custom message as the last parameter:  The error text only includes a simple human description such as "must be set" or "must be a valid email". When adding new validations, make sure that they can be displayed properly when joined with commas. A text such as "Error: this field must be higher than 42" would look weird:  You can set your own errors with v.Append():  Some validators return the parsed value, which makes it easier both validate and get a useful value at the same time:
Keywords: go