我想立即加载页面，然后加载数据以填充select2框。使用Knockout，我最终没有得到任何错误，但在我的select2 select框中看不到任何项目。从服务器同步加载工作，但非常慢（因为获取app_names）。我到目前为止：
<head>
<meta charset="utf-8">
<meta http-equiv="X-UA-Compatible" content="IE=edge">
<meta name="viewport" content="width=device-width, initial-scale=1">
<title>Admin suite</title>
<!-- Load javascript libraries -->
<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.1.1/jquery.min.js"></script>
<script src="//cdnjs.cloudflare.com/ajax/libs/twitter-bootstrap/3.3.1/js/bootstrap.min.js"></script>
<script src="//cdnjs.cloudflare.com/ajax/libs/select2/4.0.0/js/select2.min.js"></script>
<link href="https://cdnjs.cloudflare.com/ajax/libs/twitter-bootstrap/3.3.4/css/bootstrap.css" rel="stylesheet">
<!-- best interactive input box -->
<link href="//cdnjs.cloudflare.com/ajax/libs/select2/4.0.0/css/select2.min.css" rel="stylesheet" />
<script type="text/javascript" src="//cdn.jsdelivr.net/momentjs/latest/moment.min.js"></script>
<script type="text/javascript" src="//cdn.jsdelivr.net/bootstrap.daterangepicker/2/daterangepicker.js"></script>
<link rel="stylesheet" type="text/css" href="//cdn.jsdelivr.net/bootstrap.daterangepicker/2/daterangepicker.css" />
<script type="text/javascript" src="https://cdnjs.cloudflare.com/ajax/libs/underscore.js/1.8.3/underscore-min.js"></script>
<script type="text/javascript" src="https://cdnjs.cloudflare.com/ajax/libs/knockout/3.4.1/knockout-min.js"></script>
<link href="https://cdnjs.cloudflare.com/ajax/libs/select2/4.0.3/css/select2.min.css" rel="stylesheet">
<script type="text/javascript" src="https://cdnjs.cloudflare.com/ajax/libs/select2/4.0.3/js/select2.min.js"></script>
<!-- semantic -->
<!-- <link href="https://cdnjs.com/libraries/semantic-ui" rel="stylesheet"/> -->
<style>
.center {
float: none;
margin-left: auto;
margin-right: auto;
}
#centered {
width: 50%;
margin: 0 auto;
margin-top: 100
}
#middleman-datepicker {
cursor: pointer;
}
.column { float: left; padding: 5px 10px; }
.row { overflow: hidden; }
label {
display: -webkit-box;
display: -webkit-flex;
display: -ms-flexbox;
display: flex;
-webkit-box-align: center;
-webkit-align-items: center;
-ms-flex-align: center;
align-items: center;
}
input[type=radio],
input[type=checkbox] {
-webkit-box-flex: 0;
-webkit-flex: none;
-ms-flex: none;
flex: none;
margin-right: 10px;
}
.btn-primary,
.btn-primary:active,
.btn-primary:visited,
.btn-primary:focus {
background-color: #f49e42;
border-color: #8064A2;
}
.btn-primary:focus {
background-color: #f49542;
}
.btn-primary:hover {
background-color: #f48c42;
}
</style>
<meta id="my-data"
data-app-names="["cart", "catalog", "common-ui", "content", "ContentServices", "cyc", "deliverFromStore", "fbr", "fbt", "irg", "localization", "mylist-domain-service", "mylist-service", "mylist-ui", "nlpplus-service", "nlpservices", "orangegraph", "passbookService", "pricing", "promotion", "recommendations", "registry", "relatedsearch", "review_service", "sbotd-svcs", "SearchNavServices", "shipping", "SpecialBuy", "store-search", "storefinder", "typeahead2", "vectorsearch", "wayfinder"]">
<style>
.deactivate-services-box,
.delete-services-box {
width: 400px;
}
.clear-button {
margin-left: 10px;
}
</style>
</head>
<body>
<nav class="navbar navbar-default navbar-fixed-top">
<div class="container">
<div class="navbar-header">
<button type="button" class="navbar-toggle collapsed" data-toggle="collapse" data-target="#bs-example-navbar-collapse-1">
<span class="sr-only">Toggle Navigation</span>
<span class="icon-bar"></span>
<span class="icon-bar"></span>
<span class="icon-bar"></span>
</button>
<a class="navbar-brand" href="/">SLO admin suite</a>
</div>
<a data-toggle="dropdown" class="dropdown-toggle" href="#">
<div id="navbar" class="navbar-collapse collapse">
<ul class="nav navbar-nav navbar-right">
<li class="dropdown">
Navigate
<span class="caret"></span>
<ul class="dropdown-menu" aria-labelledby="dropdownMenu1">
<li class="dropdown-header"><a href="/">Middleman backfill</a></li>
<li class="dropdown-header"><a href="/healthchecks">Healthcheck statuses</a></li>
<li class="dropdown-header"><a href="/delete-services">Delete/deactivate services</a></li>
</ul></li>
</ul>
</div></a>
</div>
</nav>
<script type="text/javascript">
</script>
<div style="padding-top: 90px; float: left;" class="container">
<div >
<div class="">
<!-- https://select2.github.io/examples.html -->
<meta id="my-data"
data-app-names="["cart", "catalog", "common-ui", "content", "ContentServices", "cyc", "deliverFromStore", "fbr", "fbt", "irg", "localization", "mylist-domain-service", "mylist-service", "mylist-ui", "nlpplus-service", "nlpservices", "orangegraph", "passbookService", "pricing", "promotion", "recommendations", "registry", "relatedsearch", "review_service", "sbotd-svcs", "SearchNavServices", "shipping", "SpecialBuy", "store-search", "storefinder", "typeahead2", "vectorsearch", "wayfinder"]">
<style>
.deactivate-services-box,
.delete-services-box {
width: 400px;
}
.clear-button {
margin-left: 10px;
}
</style>
<body>
<div id="centered">
<span data-bind="visible: currently_running_ajax">
<h4>Pretending to run deactivation/deletion for 3 secs...</h4>
<p><img src="/static/img/loader.gif"/></p>
</span>
<div id="ajax-return-error-message" style="position:fixed; top:10%; right:45%; color: red; z-index: 999; display: none;"></div>
<h2>Deactivate services</h2>
<select class="deactivate-services-box" multiple="multiple" data-bind="foreach: app_names">
<option data-bind="value: $data, text: $data"></option>
</select>
<button id="deactivate-clear-all-button" class="clear-button">Clear all</button>
<h2>Permanently delete services</h2>
<select class="delete-services-box" multiple="multiple" data-bind="foreach: app_names">
<option data-bind="value: $data, text: $data"></option>
</select>
<button id="delete-clear-all-button" class="clear-button">Clear all</button>
<br><br>
<p id="empty-set-error-message" style="color: red; display: none;">Please make a selection</p>
<button id="submit-button" data-bind="click: submit_deactivation_and_or_deletion" class="btn-primary btn-lg" style="margin-left: 20px; ">Submit</button>
<button id="submit-button" data-bind="click: submit_fails_demo" class="btn-info btn-lg" style="margin-left: 20px; ">Submit will fail</button>
</div>
<script type="text/javascript">
var app_names = [];
console.log("app names 1");
// knockout
function DeleteServicesViewModel(){
var self = this;
self.app_names = app_names;
console.log("app names 2");
self.currently_running_ajax = ko.observable(false);
// var djangoData = $('#my-data').data();
// self.app_names = djangoData.appNames;
self.find_any_duplicates = function(list_one, list_two){
var duplicates = [];
for (i = 0; i < list_one.length; i++){
var item = list_one[i];
if (_.contains(list_two, item)){
duplicates.push(item);
}
}
return duplicates;
}
self.display_error_message = function(error){
setTimeout(
function() {
$("#ajax-return-error-message").text(error)
$("#ajax-return-error-message").slideDown(500, function(){
setTimeout(function(){
$("#ajax-return-error-message").slideUp(500);
}, 2600);
});
}, 300
);
}
self.submit_deactivation_and_or_deletion = function(){
var deactivate_values = $deactivate_services_box.val();
var deletion_values = $delete_services_box.val();
// alert(deactivate_values);
if (deactivate_values.length == 0 && deletion_values.length == 0){
$("#empty-set-error-message").slideDown(500, function(){
setTimeout(function(){
$("#empty-set-error-message").slideUp(500);
}, 1700);
});
return;
}
var duplicates = self.find_any_duplicates(deactivate_values, deletion_values);
if (duplicates.length){
alert("We cannot both delete and deactivate the same item. You have the following duplicates:\n\n%dups%\n\nPlease remove duplicates".replace("%dups%", duplicates));
return;
}
console.log('duplicates: ', duplicates);
self.currently_running_ajax(true);
$.ajax({
url: "/run-deactivation-and-deletion",
method: "POST",
headers: {
"Content-Type": "application/json"
},
data: ko.toJSON(
{ deactivate_list: deactivate_values, deletion_list: deletion_values }
),
success: function(data) {
console.log("worked");
$deactivate_services_box.val(null).trigger("change");
$delete_services_box.val(null).trigger("change");
},
error: function(xhr, textStatus, error) {
console.log("failed");
console.log(error);
self.currently_running_ajax(false);
self.display_error_message(error);
},
complete: function(){
self.currently_running_ajax(false);
}
});
}
// TODO: delete after demo
self.submit_fails_demo = function(){
var deactivate_values = $deactivate_services_box.val();
var deletion_values = $delete_services_box.val();
// alert(deactivate_values);
if (deactivate_values.length == 0 && deletion_values.length == 0){
$("#empty-set-error-message").slideDown(500, function(){
setTimeout(function(){
$("#empty-set-error-message").slideUp(500);
}, 1700);
});
return;
}
var duplicates = self.find_any_duplicates(deactivate_values, deletion_values);
if (duplicates.length){
alert("We cannot both delete and deactivate the same item. You have the following duplicates:\n\n%dups%\n\nPlease remove duplicates".replace("%dups%", duplicates));
return;
}
console.log('duplicates: ', duplicates);
self.currently_running_ajax(true);
$.ajax({
url: "/run-deactivation-and-deletion-fails-demo",
method: "POST",
headers: {
"Content-Type": "application/json"
},
data: ko.toJSON(
{ deactivate_list: deactivate_values, deletion_list: deletion_values }
),
// designed to fail for demo
error: function(xhr, textStatus, error) {
console.log("failed");
console.log(error);
self.currently_running_ajax(false);
self.display_error_message(error);
},
complete: function(){
self.currently_running_ajax(false);
}
});
}
}
$.getJSON("/app-names", function(data){
var app_names_json_string = data.app_names;
var app_names = JSON.parse(data.app_names);
console.log("app names 3");
ko.applyBindings(new DeleteServicesViewModel(app_names) );
var $deactivate_services_box = $(".deactivate-services-box");
var $delete_services_box = $(".delete-services-box");
$deactivate_services_box.select2();
$delete_services_box.select2();
$("#deactivate-clear-all-button").on("click", function () { $deactivate_services_box.val(null).trigger("change"); });
$("#delete-clear-all-button").on("click", function () { $delete_services_box.val(null).trigger("change"); });
});
// ko.applyBindings(new DeleteServicesViewModel() );
</script>
</body>
</div><br>
</div>
</div>
</body>
</html>
wait for ajax result to bind knockout model
中找到了帮助页面加载的灵感我想加载html，我会做旋转的gif，说＆＃34;加载＆＃34;，进行AJAX调用以获取app_names，以及app_names到达时我将它们添加到select2框并初始化select2。
答案 0 :(得分：2)
这可能有助于您在AJAX调用后将项目包装到DOM中。
首先初始化你的viewmodel（在我的实例中为var PageModel）。
选择列表是 observableArrays 。将它们初始化为空，进行ajax调用。
ajax调用是延迟的，.then（）函数有两个参数，xhr成功，xhr失败。
如果ajax成功，则将结果放入observableArray。
在你的html中设置一些条件，以防止KO抛出错误，说这里没有数据，或者你试图访问的属性不可用。
最后捎带这样一个事实：你可以订阅observable并在值改变时做一些事情，在这种情况下，它从一个空数组变为一个带数据的数组。如果您知道它有数据，请按照您认为合适的方式初始化您的select2内容。
你可以使用对数据的异步调用来做各种简洁的事情。您可以使用单击绑定来运行一个函数，该函数将数据加载到其他一些observable中以检索项目列表或新图像（IE。第二个示例）。
var PageModel = function(r) {
var self = this;
this.Select1 = ko.observableArray([]);
self.Select1.subscribe(function (val) {
if (val) {
// Run function to initialize Select2 box
// $('#some-select2-thingy').select2 stuff or whatever
console.log('This select has data now');
}
});
this.Loading1 = ko.observable(false);
this.Errors = ko.observableArray([]);
ajaxCall('https://api.punkapi.com/v2/beers', 'GET', self.Select1, self.Loading1, self.Errors);
this.Image = ko.observable();
this.Loading2 = ko.observable(false);
this.LoadImage = function() {
ajaxCall('https://api.giphy.com/v1/gifs/random?api_key=dc6zaTOxFJmzC&tag=american+psycho', 'GET', self.Image, self.Loading2, self.Errors)
}
this.ClearImage = function () {
self.Image(null);
}
};
window.model = new PageModel();
ko.applyBindings(model);
function ajaxCall(url, method, selectObj, loadingObj, errorObj) {
return $.when($.ajax({
url: url,
method: method,
beforeSend: function() {
loadingObj(true);
}
})).then(function(response) {
selectObj(response);
loadingObj(false);
}, function(error) {
errorObj.push(error);
});
};<link href="https://cdnjs.cloudflare.com/ajax/libs/twitter-bootstrap/3.3.7/css/bootstrap.min.css" rel="stylesheet"/>
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/knockout/3.2.0/knockout-min.js"></script>
<div class="container-fluid" style="margin-top: 30px;">
<div class="row" style="margin-bottom: 30px;">
<div class="col-sm-6 col-sm-push-3">
<p class="alert alert-info" data-bind="visible: Loading1()">Loading...</p>
<!-- ko if: Select1().length && !Loading1() -->
<select id="some-select2-thingy" class="form-control" data-bind="options: Select1, optionsText: 'name', optionsValue: 'id', optionsCaption: '- Select a Beer -'"></select>
<!-- /ko -->
</div>
</div>
<div class="row">
<div class="col-sm-6 col-sm-push-3">
<div class="text-center" style="margin-bottom: 10px;">
<button class="btn btn-info" data-bind="click: LoadImage, text: Image() ? 'Get A Different Image' : 'Get An Image'">Get An Image</button>
<button class="btn btn-danger" data-bind="click: ClearImage, visible: Image()">Clear Image</button>
</div>
<p class="alert alert-info" data-bind="visible: Loading2()">Loading...</p>
<!-- ko if: Image() && !Loading2() -->
<!-- ko with: Image -->
<div class="text-center">
<img data-bind="attr: {'src': data.fixed_height_downsampled_url}">
</div>
<!-- /ko -->
<!-- /ko -->
</div>
</div>
</div>
答案 1 :(得分：2)
这是一个工作小提琴，用于从ajax调用中数据绑定jquery select2。 http://jsfiddle.net/LkqTU/33425/
不确定是否有更好的方法可以做到这一点但是我将数据放在自定义绑定的更新部分而不是init中，因为它是由ajax加载的，并且最初可能不是它们。
ko.bindingHandlers.select2 = {
init: function(element, valueAccessor, allBindings, viewModel, bindingContext) {
ko.bindingHandlers.value.init(element,valueAccessor, allBindings);
$(element).select2({
})
},
update: function(element, valueAccessor, allBindings, viewModel, bindingContext) {
var data = allBindings.get('select2Data');
var dataUnwrapped = ko.toJS(data);
$(element).select2({
data: dataUnwrapped
})
var value = valueAccessor();
ko.bindingHandlers.value.update(element,valueAccessor);
}
};