如何在带有复杂模型的Knockout JS上刷新JSON或将JSON加载到我的viewModel [英] How can I refresh or load JSON to my viewModel on Knockout JS with complex models
本文介绍了如何在带有复杂模型的Knockout JS上刷新JSON或将JSON加载到我的viewModel的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！
问题描述
我从这里派生代码: http://kindohm.github.io/knockout-query-builder/
该代码在客户端运行良好. 但是，当我尝试将viewModel另存为JSON，然后从服务器检索数据时，UI根本不会刷新.
这是原始的viewModel:
window.QueryBuilder = (function(exports, ko){
var Group = exports.Group;
function ViewModel() {
var self = this;
self.group = ko.observable(new Group());
// the text() function is just an example to show output
self.text = ko.computed(function(){
return self.group().text();
});
}
exports.ViewModel = ViewModel;
return exports;
})(window.QueryBuilder || {}, window.ko);
我将下一个方法添加到viewModel
self.Save = function () {
console.log(ko.toJSON(self));
}
将此按钮添加到视图
<input type="submit" value="Save" data-bind="click: Save"/>
这是组viewModel:
window.QueryBuilder = (function(exports, ko){
var Condition = exports.Condition;
function Group(data){
var self = this;
self.templateName = data.templateName;
self.children = ko.observableArray(data.children);
self.logicalOperators = ko.observableArray(data.logicalOperators);
self.selectedLogicalOperator = ko.observable(data.selectedLogicalOperator);
// give the group a single default condition
self.children.push(new Condition());
self.addCondition = function(){
self.children.push(new Condition());
};
self.addGroup = function(){
self.children.push(new Group());
};
self.removeChild = function(child){
self.children.remove(child);
};
// the text() function is just an example to show output
self.text = ko.computed(function(){
var result = '(';
var op = '';
for (var i = 0; i < self.children().length; i++){
var child = self.children()[i];
console.log(child);
result += op + child.text();
op = ' ' + self.selectedLogicalOperator() + ' ';
}
return result += ')';
});
}
exports.Group = Group;
return exports;
})(window.QueryBuilder || {}, window.ko);
因此，当我按下保存"按钮时，控制台将显示此viewModel的JSON，此处一切正常.
这是返回的JSON:
{"group":{"templateName":"group-template","children":[{"templateName":"condition-template","fields":["Points","Goals","Assists","Shots","Shot%","PPG","SHG","Penalty Mins"],"selectedField":"Points","comparisons":["=","<>","<","<=",">",">="],"selectedComparison":"=","value":0,"text":"Points = 0"},{"templateName":"condition-template","fields":["Points","Goals","Assists","Shots","Shot%","PPG","SHG","Penalty Mins"],"selectedField":"Points","comparisons":["=","<>","<","<=",">",">="],"selectedComparison":"=","value":0,"text":"Points = 0"},{"templateName":"condition-template","fields":["Points","Goals","Assists","Shots","Shot%","PPG","SHG","Penalty Mins"],"selectedField":"Points","comparisons":["=","<>","<","<=",">",">="],"selectedComparison":"=","value":0,"text":"Points = 0"}],"logicalOperators":["AND","OR"],"selectedLogicalOperator":"AND","text":"(Points = 0 AND Points = 0 AND Points = 0)"},"text":"(Points = 0 AND Points = 0 AND Points = 0)"}
我做了一个简单的技巧来避免与服务器的连接，所以我将json复制并粘贴到load事件上，然后发送给viewModel的构造函数:
var vm;
window.addEventListener('load', function(){
var json = {"group":{"templateName":"group-template","children":[{"templateName":"condition-template","fields":["Points","Goals","Assists","Shots","Shot%","PPG","SHG","Penalty Mins"],"selectedField":"Points","comparisons":["=","<>","<","<=",">",">="],"selectedComparison":"=","value":0,"text":"Points = 0"},{"templateName":"condition-template","fields":["Points","Goals","Assists","Shots","Shot%","PPG","SHG","Penalty Mins"],"selectedField":"Points","comparisons":["=","<>","<","<=",">",">="],"selectedComparison":"=","value":0,"text":"Points = 0"},{"templateName":"condition-template","fields":["Points","Goals","Assists","Shots","Shot%","PPG","SHG","Penalty Mins"],"selectedField":"Points","comparisons":["=","<>","<","<=",">",">="],"selectedComparison":"=","value":0,"text":"Points = 0"}],"logicalOperators":["AND","OR"],"selectedLogicalOperator":"AND","text":"(Points = 0 AND Points = 0 AND Points = 0)"},"text":"(Points = 0 AND Points = 0 AND Points = 0)"};
vm = new QueryBuilder.ViewModel(json);
ko.applyBindings(vm);
}, true);
然后我修改viewModel以接收json参数
window.QueryBuilder = (function(exports, ko){
var Group = exports.Group;
function ViewModel(json) {
var self = this;
self.group = ko.observable(json.group);
// the text() function is just an example to show output
self.text = ko.computed(function(){
return self.group().text();
});
self.Save = function () {
console.log(ko.toJSON(self));
}
}
exports.ViewModel = ViewModel;
return exports;
})(window.QueryBuilder || {}, window.ko);
刷新index.html时，视图永远不会正确加载，并在JS控制台上显示此错误:
TypeError: self.group(...).text is not a function
return self.group().text();
有人知道我的错误在哪里?
我遇到的最后一个问题与孩子的text()函数有关. 我通过使用try/catch来解决此问题.因此，当viewModel是新的时，它具有text()函数，但是当加载时，text()不存在，因此我直接从文本"字段中获取值.
try {
result += op + child.text();
}
catch(err) {
result += op + child.text;
}
问题出在组"类和条件"类上. 这是当前有效的代码:
window.QueryBuilder = (function(exports, ko){
var Condition = exports.Condition;
function Group(data){
var self = this;
self.templateName = data.templateName;
self.children = ko.observableArray(data.children);
self.logicalOperators = ko.observableArray(data.logicalOperators);
self.selectedLogicalOperator = ko.observable(data.selectedLogicalOperator);
// give the group a single default condition
self.children.push(new Condition(data.children[0]));
self.addCondition = function(){
self.children.push(new Condition());
};
self.addGroup = function(){
self.children.push(new Group());
};
self.removeChild = function(child){
self.children.remove(child);
};
// the text() function is just an example to show output
self.text = ko.computed(function(){
var result = '(';
var op = '';
for (var i = 0; i < self.children().length; i++){
var child = self.children()[i];
try {
result += op + child.text();
}
catch(err) {
result += op + child.text;
}
op = ' ' + self.selectedLogicalOperator() + ' ';
}
return result += ')';
});
}
exports.Group = Group;
return exports;
})(window.QueryBuilder || {}, window.ko);
window.QueryBuilder = (function(exports, ko){
function Condition(data){
var self = this;
self.templateName = data.templateName;
self.fields = ko.observableArray(data.fields);
self.selectedField = ko.observable(data.selectedField);
self.comparisons = ko.observableArray(data.comparisons);
self.selectedComparison = ko.observable(data.selectedComparison);
self.value = ko.observable(data.value);
// the text() function is just an example to show output
self.text = ko.computed(function(){
return self.selectedField() +
' ' +
self.selectedComparison() +
' ' +
self.value();
});
}
exports.Condition = Condition;
return exports;
})(window.QueryBuilder || {}, window.ko);
解决方案
您应该采用与加载self.group = ko.observable(new Group());时类似的方法，而不是self.group = ko.observable(json.group);，但这一次在
self.group = ko.observable(new Group(json.group));
我看不到Group的定义位置，但是您应该确保它能够处理并将现在传递的JSON转换为可观察对象.
I fork the code from here: http://kindohm.github.io/knockout-query-builder/
The code works nice on the client side. But when I try to save the viewModel as JSON and then retrieve the data from the server the UI never refresh at all.
This is the original viewModel:
window.QueryBuilder = (function(exports, ko){
var Group = exports.Group;
function ViewModel() {
var self = this;
self.group = ko.observable(new Group());
// the text() function is just an example to show output
self.text = ko.computed(function(){
return self.group().text();
});
}
exports.ViewModel = ViewModel;
return exports;
})(window.QueryBuilder || {}, window.ko);
I be added the next method to the viewModel
self.Save = function () {
console.log(ko.toJSON(self));
}
Added this button to the view
<input type="submit" value="Save" data-bind="click: Save"/>
This is the Group viewModel:
window.QueryBuilder = (function(exports, ko){
var Condition = exports.Condition;
function Group(data){
var self = this;
self.templateName = data.templateName;
self.children = ko.observableArray(data.children);
self.logicalOperators = ko.observableArray(data.logicalOperators);
self.selectedLogicalOperator = ko.observable(data.selectedLogicalOperator);
// give the group a single default condition
self.children.push(new Condition());
self.addCondition = function(){
self.children.push(new Condition());
};
self.addGroup = function(){
self.children.push(new Group());
};
self.removeChild = function(child){
self.children.remove(child);
};
// the text() function is just an example to show output
self.text = ko.computed(function(){
var result = '(';
var op = '';
for (var i = 0; i < self.children().length; i++){
var child = self.children()[i];
console.log(child);
result += op + child.text();
op = ' ' + self.selectedLogicalOperator() + ' ';
}
return result += ')';
});
}
exports.Group = Group;
return exports;
})(window.QueryBuilder || {}, window.ko);
So when I press the "save" button the console show the JSON from this viewModel, everything fine here.
This is the JSON returned:
{"group":{"templateName":"group-template","children":[{"templateName":"condition-template","fields":["Points","Goals","Assists","Shots","Shot%","PPG","SHG","Penalty Mins"],"selectedField":"Points","comparisons":["=","<>","<","<=",">",">="],"selectedComparison":"=","value":0,"text":"Points = 0"},{"templateName":"condition-template","fields":["Points","Goals","Assists","Shots","Shot%","PPG","SHG","Penalty Mins"],"selectedField":"Points","comparisons":["=","<>","<","<=",">",">="],"selectedComparison":"=","value":0,"text":"Points = 0"},{"templateName":"condition-template","fields":["Points","Goals","Assists","Shots","Shot%","PPG","SHG","Penalty Mins"],"selectedField":"Points","comparisons":["=","<>","<","<=",">",">="],"selectedComparison":"=","value":0,"text":"Points = 0"}],"logicalOperators":["AND","OR"],"selectedLogicalOperator":"AND","text":"(Points = 0 AND Points = 0 AND Points = 0)"},"text":"(Points = 0 AND Points = 0 AND Points = 0)"}
I make a simple hack to avoid the connection to the server, so I take that json copy and paste on the load event and send to the constructor of the viewModel:
var vm;
window.addEventListener('load', function(){
var json = {"group":{"templateName":"group-template","children":[{"templateName":"condition-template","fields":["Points","Goals","Assists","Shots","Shot%","PPG","SHG","Penalty Mins"],"selectedField":"Points","comparisons":["=","<>","<","<=",">",">="],"selectedComparison":"=","value":0,"text":"Points = 0"},{"templateName":"condition-template","fields":["Points","Goals","Assists","Shots","Shot%","PPG","SHG","Penalty Mins"],"selectedField":"Points","comparisons":["=","<>","<","<=",">",">="],"selectedComparison":"=","value":0,"text":"Points = 0"},{"templateName":"condition-template","fields":["Points","Goals","Assists","Shots","Shot%","PPG","SHG","Penalty Mins"],"selectedField":"Points","comparisons":["=","<>","<","<=",">",">="],"selectedComparison":"=","value":0,"text":"Points = 0"}],"logicalOperators":["AND","OR"],"selectedLogicalOperator":"AND","text":"(Points = 0 AND Points = 0 AND Points = 0)"},"text":"(Points = 0 AND Points = 0 AND Points = 0)"};
vm = new QueryBuilder.ViewModel(json);
ko.applyBindings(vm);
}, true);
Then I modify the viewModel to recibe the json parameter
window.QueryBuilder = (function(exports, ko){
var Group = exports.Group;
function ViewModel(json) {
var self = this;
self.group = ko.observable(json.group);
// the text() function is just an example to show output
self.text = ko.computed(function(){
return self.group().text();
});
self.Save = function () {
console.log(ko.toJSON(self));
}
}
exports.ViewModel = ViewModel;
return exports;
})(window.QueryBuilder || {}, window.ko);
When I refresh the index.html the view is never loaded correctly and show this error on the JS console:
TypeError: self.group(...).text is not a function
return self.group().text();
Someone knows where is my mistake?
The last problem I had was related to the text() function on the child. I fix this with the use of try/catch. So when the viewModel are new it have the text() function, but when this is loadad the text() does not exist, so I take the value directly from the "text" field.
try {
result += op + child.text();
}
catch(err) {
result += op + child.text;
}
The problem was on the Group class and Condition class. This is the current and working code:
window.QueryBuilder = (function(exports, ko){
var Condition = exports.Condition;
function Group(data){
var self = this;
self.templateName = data.templateName;
self.children = ko.observableArray(data.children);
self.logicalOperators = ko.observableArray(data.logicalOperators);
self.selectedLogicalOperator = ko.observable(data.selectedLogicalOperator);
// give the group a single default condition
self.children.push(new Condition(data.children[0]));
self.addCondition = function(){
self.children.push(new Condition());
};
self.addGroup = function(){
self.children.push(new Group());
};
self.removeChild = function(child){
self.children.remove(child);
};
// the text() function is just an example to show output
self.text = ko.computed(function(){
var result = '(';
var op = '';
for (var i = 0; i < self.children().length; i++){
var child = self.children()[i];
try {
result += op + child.text();
}
catch(err) {
result += op + child.text;
}
op = ' ' + self.selectedLogicalOperator() + ' ';
}
return result += ')';
});
}
exports.Group = Group;
return exports;
})(window.QueryBuilder || {}, window.ko);
window.QueryBuilder = (function(exports, ko){
function Condition(data){
var self = this;
self.templateName = data.templateName;
self.fields = ko.observableArray(data.fields);
self.selectedField = ko.observable(data.selectedField);
self.comparisons = ko.observableArray(data.comparisons);
self.selectedComparison = ko.observable(data.selectedComparison);
self.value = ko.observable(data.value);
// the text() function is just an example to show output
self.text = ko.computed(function(){
return self.selectedField() +
' ' +
self.selectedComparison() +
' ' +
self.value();
});
}
exports.Condition = Condition;
return exports;
})(window.QueryBuilder || {}, window.ko);
解决方案
Instead of self.group = ko.observable(json.group);, you should take a similar approach as you did on load self.group = ko.observable(new Group());, but this time pass the json.group data in Group
self.group = ko.observable(new Group(json.group));
I don't see where Group is defined, but you should make sure that it is able to handle and convert the JSON you now pass in, into observables.
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