validator

A powerful validator that supports struct tag expression.

Feature

• Support for a variety of common operator
• Support for accessing arrays, slices, members of the dictionary
• Support access to any field in the current structure
• Support access to nested fields, non-exported fields, etc.
• Support registers validator function expression
• Built-in len, sprintf, regexp, email, phone functions
• Support simple mode, or specify error message mode
• Use offset pointers to directly take values, better performance
• Required go version ≥1.9

Example

package validator_test

import (
	"fmt"

	vd "github.com/bytedance/go-tagexpr/validator"
)

func Example() {
	type InfoRequest struct {
		Name         string `vd:"($!='Alice'||(Age)$==18) && regexp('\\w')"`
		Age          int    `vd:"$>0"`
		Email        string `vd:"email($)"`
		Phone1       string `vd:"phone($)"`
		Phone2       string `vd:"phone($,'CN')"`
		*InfoRequest `vd:"?"`
		Info1        *InfoRequest `vd:"?"`
		Info2        *InfoRequest `vd:"-"`
	}
	info := InfoRequest{
		Name:   "Alice",
		Age:    18,
		Email:  "[email protected]",
		Phone1: "+8618812345678",
		Phone2: "18812345678",
	}
	fmt.Println(vd.Validate(info) == nil)

	type A struct {
		A    int `vd:"$<0||$>=100"`
		Info interface{}
	}
	info.Email = "xxx"
	a := &A{A: 107, Info: info}
	fmt.Println(vd.Validate(a))

	type B struct {
		B string `vd:"len($)>1 && regexp('^\\w*$')"`
	}
	b := &B{"abc"}
	fmt.Println(vd.Validate(b) == nil)

	type C struct {
		C bool `vd:"@:(S.A)$>0 && !$; msg:'C must be false when S.A>0'"`
		S *A
	}
	c := &C{C: true, S: a}
	fmt.Println(vd.Validate(c))

	type D struct {
		d []string `vd:"@:len($)>0 && $[0]=='D'; msg:sprintf('invalid d: %v',$)"`
	}
	d := &D{d: []string{"x", "y"}}
	fmt.Println(vd.Validate(d))

	type E struct {
		e map[string]int `vd:"len($)==$['len']"`
	}
	e := &E{map[string]int{"len": 2}}
	fmt.Println(vd.Validate(e))

	// Customizes the factory of validation error.
	vd.SetErrorFactory(func(failPath, msg string) error {
		return fmt.Errorf(`{"succ":false, "error":"validation failed: %s"}`, failPath)
	})

	type F struct {
		f struct {
			g int `vd:"$%3==0"`
		}
	}
	f := &F{}
	f.f.g = 10
	fmt.Println(vd.Validate(f))

	fmt.Println(vd.Validate(map[string]*F{"a": f}))
	fmt.Println(vd.Validate(map[*F]int{f: 1}))
	fmt.Println(vd.Validate([][1]*F{{f}}))
	fmt.Println(vd.Validate((*F)(nil)))
	fmt.Println(vd.Validate(map[string]*F{}))
	fmt.Println(vd.Validate([]*F{}))

	// Output:
	// true
	// invalid parameter: Info.Email
	// true
	// C must be false when S.A>0
	// invalid d: [x y]
	// invalid parameter: e
	// {"succ":false, "error":"validation failed: f.g"}
	// {"succ":false, "error":"validation failed: {K:a}.f.g"}
	// {"succ":false, "error":"validation failed: {}.f.g"}
	// {"succ":false, "error":"validation failed: [0][0].f.g"}
	// unsupport data: nil
	// <nil>
	// <nil>
}

Syntax

Struct tag syntax spec:

type T struct {
	// Simple model
    Field1 T1 `tagName:"expression"`
	// Specify error message mode
    Field2 T2 `tagName:"@:expression; msg:expression2"`
	// Omit it
    Field3 T3 `tagName:"-"`
    // Omit it when it is nil
    Field4 T4 `tagName:"?"`
    ...
}

Operator or Operand	Explain
true false	boolean
0 0.0	float64 "0"
''	String
\\'	Escape ' delims in string
\"	Escape " delims in string
nil	nil, undefined
!	not, suitable for bool, string, float64, nil, $ and ()
+	Digital addition or string splicing
-	Digital subtraction or negative
*	Digital multiplication
/	Digital division
%	division remainder, as: float64(int64(a)%int64(b))
==	eq
!=	ne
>	gt
>=	ge
<	lt
<=	le
&&	Logic and
||	Logic or
()	Expression group
(X)$	Struct field value named X
(X.Y)$	Struct field value named X.Y
$	Shorthand for (X)$, omit (X) to indicate current struct field value
(X)$['A']	Map value with key A or struct A sub-field in the struct field X
(X)$[0]	The 0th element or sub-field of the struct field X(type: map, slice, array, struct)
len((X)$)	Built-in function len, the length of struct field X
regexp('^\\w*$', (X)$)	Regular match the struct field X, return boolean
regexp('^\\w*$')	Regular match the current struct field, return boolean
sprintf('X value: %v', (X)$)	fmt.Sprintf, format the value of struct field X
email((X)$)	Regular match the struct field X, return true if it is email
phone((X)$,<'defaultRegion'>)	Regular match the struct field X, return true if it is phone

Operator priority(high -> low):

• () ! bool float64 string nil
• * / %
• + -
• < <= > >=
• == !=
• &&
• ||