constraint.IsNull

Constraint: IsNull

Description

Is a utility constraint to check that a value is null

Normally, null checking would be performed by the PropertyValidator.NotNull setting - however, it may be the case that, under certain conditions, null is the required value

V8n Tag Abbreviation

null

Fields

Field	Type	Description
Message	string	the violation message to be used if the constraint fails. If empty, the default message is used
Stop	bool	when set to true, Stop prevents further validation checks on the property if this constraint fails

Examples

Programmatic example...

package main

import (
    "fmt"

    "github.com/marrow16/valix"
)

func main() {
    validator := &valix.Validator{
        Properties: valix.Properties{
            "foo": {
                Type: valix.JsonAny,
                Constraints: valix.Constraints{
                    &valix.IsNull{},
                },
            },
        },
    }

    ok, violations, _ := validator.ValidateString(`{"foo": "not null"}`)
    fmt.Printf("Passed? %v\n", ok)
    for i, v := range violations {
        fmt.Printf("Violation[%d] Message: %s, Property: %s, Path: %s\n", i+1, v.Message, v.Property, v.Path)
    }

    ok, violations, _ = validator.ValidateString(`{"foo": null}`)
    fmt.Printf("Passed? %v\n", ok)
    for i, v := range violations {
        fmt.Printf("Violation[%d] Message: %s, Property: %s, Path: %s\n", i+1, v.Message, v.Property, v.Path)
    }
}

try on go-playground

Struct v8n tag example...

package main

import (
    "fmt"

    "github.com/marrow16/valix"
)

type MyStruct struct {
    Foo interface{} `json:"foo" v8n:"&null"`
}

var validator = valix.MustCompileValidatorFor(MyStruct{})

func main() {
    my := &MyStruct{}

    ok, violations, _ := validator.ValidateStringInto(`{"foo": "not null"}`, my)
    fmt.Printf("Passed? %v\n", ok)
    for i, v := range violations {
        fmt.Printf("Violation[%d] Message: %s, Property: %s, Path: %s\n", i+1, v.Message, v.Property, v.Path)
    }

    ok, violations, _ = validator.ValidateStringInto(`{"foo": null}`, my)
    fmt.Printf("Passed? %v\n", ok)
    for i, v := range violations {
        fmt.Printf("Violation[%d] Message: %s, Property: %s, Path: %s\n", i+1, v.Message, v.Property, v.Path)
    }
}

try on go-playground