Validation

This validation package is designed to make adding validation to API endpoints as clear and easy to use as possible. Although common validation rules exist for use, it's easy to create custom ones as well as custom error messages.

TODO

• See if it's possible to add required validation into RunValidation function.
• Add CI/CD to GitHub rules - golint and automated tests.

Example Usage

You define the rules for each of the struct properties that need to be tested. Each validation function should be placed comma-separated in the Function property of the given rule.

import "github.com/doublehops/dhapi/validator"

type Person struct {
    Name         string
    Age          string
    EmailAddress string
}

func main() {

    person := Person{
        Name:         "Jo",
        Age:          "Smith",
        EmailAddress: "jo.smith",
    }

    rules := []Rule{
        {"name", person.Name, false, []validator.ValidationFuncs{validator.MinLength(13, "")}},
        {"emailAddress", person.EmailAddress, false, []validator.ValidationFuncs{validator.EmailAddress("My custom error message")}},
    }
    
    errors := RunValidation(rules)
    j, _ := json.Marshal(errors)
    fmt.Println(string(j))
}

The response will contain the errors as an array per property as multiple rules for each could fail. It should be easy for any frontend to consume. An example would look like this:

{
  "emailAddress": [
    "My custom error message"
  ],
  "name": [
    "is not the minimum length"
  ]
}

Adding a Custom Validation Rule

You can create custom validation functions and use them just the same. The function must confirm to the ValidateFuncs signature. Create the function and then assign it to the variables in the rules slice like the pre-created functions.

An example would be:

func CustomValidation(errorMessage string) ValidationFunctions {
	return func(required bool, value interface{}) (bool, string) {
		if errorMessage == "" {
			errorMessage = defaultErrorMessage
		}

		var v string
		var ok bool

		if v, ok = value.(string); !ok {
			return false, errorMessage
		}

		if v == "my-custom-value" {
			return true, ""
		}

		return false, errorMessage
	}
}