jsonValidator

README

JsonValidator

JsonValidator is a package that helps create CRUD APIs by validating HTTP JSON bodies against a predefined "form" struct.

TL;DR

This is a basic example on how to use this package.

type Object struct {
    ID             *string    `validations:"type=string;required=true`
    Code           *int       `validations:"type=int;choices=1,2,3`
    Person         *Person    `validations:"type=struct`
    Owners         []string   `validations:"type=[]string`
}

form := new(Object)
validationErrors := jsonValidator.Validate(c.Body(), form)

Available validations

Types

type Object struct {
    Name           *string    `validations:"type=string`
    Code           *int       `validations:"type=int`
    Price          *float64   `validations:"type=float`
    Successful     *bool      `validations:"type=bool`
    Person         *Person    `validations:"type=struct`
    Owners         []string   `validations:"type=[]string`
    PreviousCodes  []int      `validations:"type=[]int`
    PreviousPrices []float64  `validations:"type=[]float`
    PersonList     []Person   `validations:"type=[]struct`
}

All types (besides the slices) need to be a pointer. This makes it clear what fields the user sent in the JSON. As structs have zero-values, all the basic types would get the zero-value even though the user might not be sending any value. The slices do not need this because the zero-value of it is nil. The package is capable of transforming data if necessary. For example if the form is type struct {Count int `validations:"type=int"`} and the received JSON is {'count': '12345'} the package will cast the '12345' string into an int.

Required

type Object struct {
    Name *string `validations:"type=string;required=true`
}

Min and Max

type Object struct {
    Name           *string    `validations:"type=string;min=1;max=10"`
    Code           *int       `validations:"type=int;min=1;max=10"`
    Price          *float64   `validations:"type=float;min=1;max=10"`
    Owners         []string   `validations:"type=[]string;min=1;max=2"`
    PreviousCodes  []int      `validations:"type=[]int;min=1;max=2"`
    PreviousPrices []float64  `validations:"type=[]float;min=1;max=2"`
    PersonList     []Person   `validations:"type=[]struct;min=1;max=2"`
}

Any type can have a min and max besides the 'bool' type.

The min and max functionality depends on each type:

• For type=string the min and max are the minimum/maximum length of the string.
• For type=int the min and max are the minimum/maximum number for the int.
• For type=float the min and max are the minimum/maximum number for the float.
• For type=[]string or type=[]int or type=[]float or type=[]struct the min and max are the minimum/maximum length for the array. Basically how many "options" can be selected.

Choices

type Object struct {
    Name           *string    `validations:"type=string;choices=Daniel,Jaime,Carolina"`
    Code           *int       `validations:"type=int;choices=1,2,3"`
    Price          *float64   `validations:"type=float;choices=1.0,2.0,3.0"`
    Owners         []string   `validations:"type=[]string;choices=Daniel,Jaime,Carolina"`
    PreviousCodes  []int      `validations:"type=[]int;choices=1,2,3"`
    PreviousPrices []float64  `validations:"type=[]float;choices=1.0,2.0,3.0"`
}

The package will validate the received JSON against the available choices

Structs

type Person struct {
    Name *string `validations:"type=string"`
    Age  *int    `validations:"type=int"`
}
type Object struct {
    Person     *Person   `validations:"type=struct"`
    PersonList []Person  `validations:"type=[]struct"`
}

This package is also capable of validating validations inside the defined struct

Errors

Last but not least we have the errors. The package will return the errors in the ValidationError slice.

type ValidationError struct {
	Field   string
	Message string
}

Documentation

Index

• Variables
• func LowerCase(str string) string
• func TitleCase(str string) string
• func Validate(jsonData []byte, form any) []error
• type ValidationError
  • func (vr ValidationError) Error() string
• type Validations

Variables

var DefaultChoicesSeparator = ","

var DefaultMessages = map[string]string{
	"InvalidField":     "This field is invalid.",
	"InvalidFormat":    "This field has an invalid format (%v).",
	"InvalidMinString": "This field must have at least %v characters.",
	"InvalidMaxString": "This field must not have more than %v characters.",
	"InvalidMinNumber": "This field must be bigger than %v.",
	"InvalidMaxNumber": "This field must be smaller than %v.",
	"InvalidMinList":   "This field must have at least %v elements.",
	"InvalidMaxList":   "This field must not have more than %v elements.",
	"RequiredField":    "This field is required.",
	"InvalidChoice":    "This field has an invalid choice (%v). The valid choices are (%v)",
}

var DefaultSeparator = ";"

var DefaultTagName = "validations"

Functions

func LowerCase

func LowerCase(str string) string

func TitleCase

func TitleCase(str string) string

func Validate

func Validate(jsonData []byte, form any) []error

Validate validates the json data against a form received and update the form with the parsed data.

Types

type ValidationError

type ValidationError struct {
	Field   string
	Message string
}

func (ValidationError) Error

func (vr ValidationError) Error() string

type Validations

type Validations struct {
	Type     string
	Required bool
	Min      float64
	Max      float64
	Choices  []any
}