I would like to create a constructor which can be instantiated with a json file which then is used by some private functions which in the end pass their results to a public function of the prototype. Is this the right approach?
Here more specific code:
//constructor
function queryArray(json){
this.json = json;
//init qry template with default values
function qryInit() {
var qryTemplate = {
//some stuff
}
return qryTemplate;
}
//generate array of request templates
function qryTempArray(json){
var template = qryInit();
var qryTempArray1 = [];
for(var i = 0; i < json.length; i++){
qryTempArray1.push({
'SearchIndex': json[i].SearchIndex,
'Title': json[i].Title,
'Keywords': json[i].Keywords,
'MinimumPrice': json[i].MinimumPrice,
'MaximumPrice': json[i].MaximumPrice,
'ResponseGroup': template.ResponseGroup,
'sort': template.sort
});
}
return qryTempArray1;
}
}
//function for finally building all the queries
queryArray.prototype.qryBuilder = function(){
var qryTempArray1 = [];
qryTempArray1 = qryTempArray(this.json);
//other stuff
}
If I call the qryBuilder function on an Object, I get an error
in the function qryTempArray at the json.length in the for loop (undefined).
Why that?
As the code is written above, I'm surprised you even get to the loop. It would seem you'd get undefined when you called qryBuilder();
I would expect something along the lines of the following to work.
//constructor
function queryArray(json) {
var self = this;
self.json = json;
//init qry template with default values
self.qryInit = function() {
var qryTemplate = {
//some stuff
}
return qryTemplate;
}
//generate array of request templates
self.qryTempArray = function(json) {
var template = self.qryInit();
var qryTempArray1 = [];
for (var i = 0; i < json.length; i++) {
qryTempArray1.push({
'SearchIndex': json[i].SearchIndex,
'Title': json[i].Title,
'Keywords': json[i].Keywords,
'MinimumPrice': json[i].MinimumPrice,
'MaximumPrice': json[i].MaximumPrice,
'ResponseGroup': template.ResponseGroup,
'sort': template.sort
});
}
return qryTempArray1;
}
return self;
}
queryArray.prototype.qryBuilder = function() {
var qryTempArray1 = [];
qryTempArray1 = this.qryTempArray(this.json);
return qryTempArray1;
}
var q = new queryArray([{
'SearchIndex': 0,
'Title': 'foo',
'Keywords': 'testing',
'MinimumPrice': 20,
'MaximumPrice': 40
}]);
console.log(q);
console.log(q.qryBuilder());
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);
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.
I am trying to make an angular service that returns a new object.
That's fine and good and works. new MakeRoll() creates an instance. But self.add, near the end also calls new MakeRoll() and that doesn't create an instance when I call add like I think it should.
I'm probably doing this all wrong but I haven't been able to figure it out.
var services = angular.module('services', []);
services.factory('Roll', [function() {
var MakeRoll = function () {
var self = {};
self.rolls = [];
self.add = function(number, sizeOfDice, add) {
var newRoll = {};
newRoll.number = number || 1;
newRoll.sizeOfDice = sizeOfDice || 6;
newRoll.add = add || 0;
newRoll.rollDice = function() {
var result = 0;
var results=[];
for (var i = 0; i < newRoll.number; i++) {
var roll = Math.floor(Math.random() * newRoll.sizeOfDice) + 1;
result += roll;
results.push(roll);
}
newRoll.results = results;
newRoll.result = result;
newRoll.Roll = new MakeRoll();
};
self.rolls.push(newRoll);
return self;
};
self.remove = function(index) {
self.rolls.splice(index, 1);
};
self.get = function(index) {
return self.rolls[index];
};
return self;
};
return new MakeRoll();
}
]);
angular service is designed to be singleton to accomplish some business logic, so don't mix up plain model with angular service. if you want to have more objects, just create a constructor and link it in service to be operated on.
function MakeRoll() {
...
}
angular.module('service', []).factory('Roll', function () {
var rolls = [];
return {
add: add,
remove: remove,
get: get
}
function add() {
// var o = new MakrRoll();
// rolls.push(o);
}
function remove(o) {
// remove o from rolls
}
function get(o) {
// get o from rolls
}
});
I have a class called question . I am trying to call this display method from another class by creating its correspoding object. But I get this error. Will be glad if you can help me with this.
///////////////QUESTION///////////////
function Question(id, text){
this.id = id;
this.text = text;
}
function QType1(id, text, choices, answers){
//this is true or false
Question.call(this, id, text) ;
this.choices = choices;
this.answers = answers;
}
QType1.prototype = new Question();
//inherit Question
QType1.prototype.constructor = QType1;
QType1.Display = function(){
console.log("Display Question");
}
///////////////QUIZ//////////////////
function quiz(){}
quiz.prototype.SetHomeScreen = function(x,y){
var svgCanvas = CreateCanvas(x,y);
AddText(svgCanvas,100,50, quiz_input.Settings.Layout.Text);
console.log("Text Added");
start_but = AddStartButton(svgCanvas, 300, 250);
console.log("start button Added");
start_but
.on("click", function(d,i) {
startquiz();
});
var startquiz = function(){
console.log(this);
quiz.prototype.StartQuiz();
};
}
quiz.prototype.question_objs = [];
quiz.prototype.user_ans = [];
quiz.prototype.corr_ans = [];
quiz.prototype.LoadQuestions = function(){
for(var i=0, l=questions.length; i<l; i++){
this.question_objs.push(new QType1(questions[i].id, questions[i].settings.text, questions[i].settings.choices, questions[i].settings.answers));
}
console.log(this.question_objs);
}
quiz.prototype.DisplayQuestions = function(){
var i = 0;
var l = this.question_objs.length;
while(i < l){
console.log(this.question_objs[i] instanceof QType1);
this.question_objs[i].Display();
}
}
quiz.prototype.StartQuiz = function(){
quiz.prototype.LoadQuestions();
console.log("Starting Quiz");
quiz.prototype.DisplayQuestions();
}
The Error Message which I get is.
Thanks in Advance
Two possible causes:
you didn't declare function Qtype1() {} and
you didn't instatiate a qtype1 object like so var q = new Qtype1()
EDIT: you didn't make Display a method of QType1.
The only way you could have a QType1.Display method is if you had declared QType1 as a variable, like var QType1 = {}
That way you could have a Display method directly bound to the variable. But as you declared it as a constructor you need QType1.prototype.Display = function () { console.log('Display question...'); };
Also - your inheritance is a bit messy. You're calling Question.call(this, id, text) then you're declaring QType1.prototype = new Question() and then doing the same with the constructor. You need to review your javascript prototypal inheritance theory a bit.
In my view model, I have an observable array that needs to be populated from a $.getJSON call. I would like to have a computed observable to represent the total of a "price" column contained in the JSON returned.
I've managed to populate the observable array...
(function($){
function Coupon(expiration, value) {
var self = this;
self.expiration = expiration;
self.value = value;
}
$(function() {
$.when($.getJSON(coupons_url, null)).done(function(couponsJson) {
ko.applyBindings({
coupons: ko.utils.arrayMap(couponsJson[0].objects,
function(coupon) {
return new Coupon(coupon.expiration, coupon.value);
})
savingsAvailable: ko.computed(function() {
var total = 0;
for (var i = 0; i < this.coupons().length; i++) {
total += parseFloat(this.coupons()[i].value / 100);
}
return total.toFixed(2);
})
});
});
});
})(jQuery);
...but I'm not sure how to then access the value of coupons when I try to populate the computed observable. this.coupons() errors out: "this.coupons() is not a function". What do I need to do to accomplish this, and/or what am I doing wrong?
ko.computed() takes a second parameter that defines the value of "this" when evaluating the computed observable. So what ever object hold "coupons" you would want to pass that in as the second parameter.
Or you could try something like the following create a view model instead of defining the object on the fly and passing it as a parameter to applyBindings.
var Coupon = function(expiration, value) {
var self = this;
self.expiration = expiration;
self.value = value;
}
var viewModel = function(couponsJson){
var self = this;
self.coupons = ko.utils.arrayMap(couponsJson[0].objects, function(coupon) {
return new Coupon(coupon.expiration, coupon.value);
})
self.savingsAvailable = ko.computed(function() {
var total = 0;
for (var i = 0; i < self.coupons().length; i++) {
total += parseFloat(self.coupons()[i].value / 100);
}
return total.toFixed(2);
})
}
(function($){
$(function() {
$.when($.getJSON(coupons_url, null)).done(function(couponsJson) {
var vm = new viewModel(couponsJson)
ko.applyBindings(viewModel);
});
});
})(jQuery);