Question

这与我的另一个问题here有关！我正在尝试创建自定义验证扩展程序而不使用验证库。

无法将扩展程序扩展到多个可观察对象。在下面的方案中，扩展程序应用于密码字段，但不应用于重新输入密码字段。

<!DOCTYPE html>

<html lang="en" xmlns="http://www.w3.org/1999/xhtml">
<head>
    <meta charset="utf-8" />
    <title></title>
</head>
<body>
    <script type="text/javascript" src="knockout-3.4.0.js"></script>

    Name:<input type="text" data-bind="value:Name" /><br />
    Already A User: <input type="checkbox" data-bind="checked:AlreadyUser" /><br />
    Password:<input type="password" data-bind="value:Password,visible:PasswordVisible" /><br />
    Retype Password:<input type="password" data-bind="value:RetypePassword,visible:PasswordVisible" /><br />
    <input type="button" value="Submit" onclick="validateModel();" />

    <script type="text/javascript" >
        var pageModel;

        ko.extenders.Validate = function (target, validateOptions) {
            target.HasErrors = ko.computed(function () {
                var newValue = target();

                var required = validateOptions.required();
                var validationType = validateOptions.validationType;                

                if (ko.unwrap(required)) {
                    switch (validationType) {
                        case "Text":
                            return newValue == '';
                       default:
                            target.HasErrors(false);
                            break;
                    }
                }
                return false;
            }, null, { deferEvaluation: true }).extend({ notify: 'always' });            
            return target;
        };

        //The model itself
        var ViewModel = function () {
            var self = this;
            self.Name = ko.observable('');
            self.AlreadyUser = ko.observable(false);
            //computed variable that sets the visibility of the password field. I have to clear the password when am making it invisible
            self.PasswordVisible = ko.computed(function () { return !this.AlreadyUser(); }, this).extend({ notify: 'always' });
            //this field is only required when visible
            self.Password = ko.observable('').extend({ Validate: { required: function () { return self.PasswordVisible(); }, validationType: "Text" } });
            self.RetypePassword = ko.observable('').extend({ Validate: { required: function () { return self.PasswordVisible(); }, validationType: "Text" } });                        
            self.AlreadyUser.subscribe(function (newVal) {  self.RetypePassword(''); });
            self.HasErrors = ko.computed(function () { return self.Password.HasErrors() && self.RetypePassword.HasErrors(); }, self);
        };

        //The method calls on click of button
        function validateModel() {
            alert(pageModel.HasErrors());
        }

        //create new instance of model and bind to the page
        window.onload = function () {
            pageModel = new ViewModel();
            ko.applyBindings(pageModel);
        };

    </script>
</body>
</html>

Answer 1

我将您的代码复制到交互式代码段，并注意到存在控制台错误...此外，并非computed中的所有路径都返回了值。

我已经解决了这些问题，一切都按照您的预期运作。你在发布之前检查了控制台吗？

错误：

newValue未定义

计算错误：

您必须通过调用计算方法

target()

您通过返回一个值来“设置”计算，而不是通过方法中的computedObs(newVal) 。

var pageModel; ko.extenders.Validate = function(target, validateOptions) { target.HasErrors = ko.computed(function() { var required = validateOptions.required(); var validationType = validateOptions.validationType; var newValue = target(); if (ko.unwrap(required)) { switch (validationType) { case "Text": return newValue == ''; default: return false } } return false; }, null, { deferEvaluation: true }).extend({ notify: 'always' }); return target; }; //The model itself var ViewModel = function() { var self = this; self.Name = ko.observable(''); self.AlreadyUser = ko.observable(false); //computed variable that sets the visibility of the password field. I have to clear the password when am making it invisible self.PasswordVisible = ko.computed(function() { return !this.AlreadyUser(); }, this).extend({ notify: 'always' }); //this field is only required when visible self.Password = ko.observable('').extend({ Validate: { required: function() { return self.PasswordVisible(); }, validationType: "Text" } }); self.RetypePassword = ko.observable('').extend({ Validate: { required: function() { return self.PasswordVisible(); }, validationType: "Text" } }); self.AlreadyUser.subscribe(function(newVal) { self.RetypePassword(''); }); self.HasErrors = ko.computed(function() { return self.Password.HasErrors() && self.RetypePassword.HasErrors(); }, self); }; //The method calls on click of button function validateModel() { alert(pageModel.HasErrors()); } //create new instance of model and bind to the page window.onload = function() { pageModel = new ViewModel(); ko.applyBindings(pageModel); };

.has-error { background:red; }

<script src="https://cdnjs.cloudflare.com/ajax/libs/knockout/3.2.0/knockout-min.js"></script> Name: <input type="text" data-bind="value:Name" /> <br />Already A User: <input type="checkbox" data-bind="checked:AlreadyUser" /> <br />Password: <input type="password" data-bind="value:Password, visible:PasswordVisible, css: {'has-error': Password.HasErrors }" /> <br />Retype Password: <input type="password" data-bind="value:RetypePassword,visible:PasswordVisible, css: {'has-error': RetypePassword.HasErrors }" /> <br /> <input type="button" value="Submit" onclick="validateModel();" />

knockout无法使用扩展器扩展多个可观察对象

1 个答案: