对于下拉列表框的绑定在之前的knockoutjs文章中已经介绍过，今天主要说一下级联的select，事实上，在knockoutjs里，是以数据绑定为中心的，而数据是以面向对象为前提的，而对于级联绑定来说，它也是一种面向对象里关系对象的体现，有了关系对象，我们就可以把级联很容易的开发出来，而不用像之前JS那么麻烦了。
准备数据对象
var Grade_Subject_R = function () {
var self = this;
self.Grades = [
{
'subjects': [{ 'id': '1', 'name': '语文' },
{ 'id': '2', 'name': '数学' },
{ 'id': '3', 'name': '英语' }],
'arid': '1',
'name': '小学'
},
{
'subjects': [{ 'id': '1', 'name': '语文' },
{ 'id': '2', 'name': '数学' },
{ 'id': '3', 'name': '英语' },
{ 'id': '4', 'name': '物理' },
{ 'id': '22', 'name': '化学' },
{ 'id': '23', 'name': '生物' }],
'arid': '2',
'name': '初中'
},
{
'subjects': [{ 'id': '1', 'name': '语文' },
{ 'id': '2', 'name': '数学' },
{ 'id': '3', 'name': '英语' },
{ 'id': '4', 'name': '物理' },
{ 'id': '22', 'name': '化学' },
{ 'id': '23', 'name': '生物' },
{ 'id': '24', 'name': '历史' }],
'arid': '3',
'name': '高中'
}
];
self.grade = ko.observable();
self.subject = ko.observable();
/*
当前选中的年级ＩＤ为self.grade().id
当前选中的学科ＩＤ为self.subject().id
ＨＴＭＬ代码：
<select data-bind="
options: Grades,
optionsText: 'name',
value:grade,
optionsCaption: '选择年级'">
</select>
<span data-bind="with:grade">
<select data-bind="
visible: $parent.grade,
options: Subjects,
optionsText: 'name',
value:$parent.subject,
optionsCaption: '选择学科'">
</select>
</span>
<span data-bind="with:grade">
<!-- ko foreach: Subjects -->
<input type="checkbox" data-bind="value: id, checked: $root.subject" />
<span data-bind="text: name"></span>
<!-- /ko -->
</span>
*/
}
JS代码
var model = new Grade_Subject_R();
ko.applyBindings(model); for (var i in model.Grades) {
if (model.Grades[i].arid == "") {
model.grade(model.Grades[i]);
break;
}
}
HTML代码
<select data-bind="
options: Grades,
optionsText: 'name',
value:grade,
optionsCaption: '选择年级'">
</select>
<!-- ko with:grade -->
<select data-bind="
visible:$parent.grade,
options: subjects,
optionsText: 'name',
value:$parent.subject,
optionsCaption: '选择学科'">
</select>
<!-- /ko -->
效果截图
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