jsonv

Golang validating JSON parser

Parses JSON whilst validating it. The created parsers generate useful error messages with full paths to the JSON values that triggered the parse error.

As many errors as possible are accumulated before returning, allowing APIs to provide more complete feedback rather than only propagating 1 error at a time.

Example use

import "github.com/Satook/jsonv"

type Customer struct {
	Id          int64
	Name        string
	Email       string
	Phone       string

	PublicId     string
	ReminderSent bool
}

// Example phone number parser/validator
var PhoneNumber = jsonv.String(
	jsonv.Pattern(`^+?[ 0-9]{6,}$`, "Please enter a valid Phone number, it can start with '+'."),
)

// Example email parser/validator
var EmailAddress = jsonv.String(
	jsonv.Pattern(`[@][a-zA-Z0-9-_.]+$`, "Please enter an email address, i.e. contain an '@' followed by a domain."),
)

var CreateParser = jsonv.Parser(&Customer{},
	jsonv.Struct(
		jsonv.Prop("Name", jsonv.String()),
		jsonv.PropWithDefault("Email", EmailAddress, ""),
		jsonv.PropWithDefault("Phone", PhoneNumber, ""),
		jsonv.PropWithDefault("ReminderSent", jsonv.Boolean(), false),
  )
)

The CreateParser can parse JSON and validate all properties during parsing. If a property isn't included in the parser definition, it will be left with its default value and never altered by the parser.

To parse JSON from an io.Reader named data:

var cust Customer

if err := CreateParser.Parse(data, &cust); err != nil {
  if verr, ok := err.(jsonv.ValidationError); ok {
    // we should do someting with this error, maybe propagate it back to the client?
  } else {
    // you should never get here, but it's probably worth a
    panic(err)
  }
}

If .Parse returns nil, cust will be filled in with valid data.

New types

In order to add new types that jsonv can understand, implement the SchemaType interface. For examples, check out the types_*.go files.