问题
Im trying to create a computed property to get me the sum of the length of all pages.
But i cannot figure out how to access a child so i can get the childs of that child.
App.Document = DS.Model.extend({
name: DS.attr('string'),
spreads: DS.hasMany('App.Spread'),
pagesCount: function() {
// Here is where i go wrong, i can get the length of spreads, but not access a spread to get the page length.
var spreadsLength = this.get('spreads.length');
var firstSpread = this.get('spreads')[0];
return firstSpread.get('pages.length');
}.property('spreads')
});
App.Spread = DS.Model.extend({
document: DS.belongsTo('App.Document'),
pages: DS.hasMany('App.Page')
})
App.Page = DS.Model.extend({
spread: DS.belongsTo('App.Spread'),
page_name: DS.attr('string'),
page_items: DS.hasMany('DS.PageItem')
})
回答1:
Here is an example of how you get access to the first object in the array of spreads:
App.Document = DS.Model.extend({
name: DS.attr('string'),
spreads: DS.hasMany('App.Spread'),
pagesCount: function() {
// Here is where i go wrong, i can get the length of spreads, but not access a spread to get the page length.
var spreadsLength = this.get('spreads.length');
var firstSpread = this.get('spreads').objectAt(0);
// var firstSpread = this.get('spreads.firstObject'); // elegant way to first Object
return firstSpread.get('pages.length');
}.property('spreads.firstObject.pages.length')
});
But i guess you want to get the total number of pages here. So, here is an example how to iterate the spreads and sum the number of pages:
App.Document = DS.Model.extend({
name: DS.attr('string'),
spreads: DS.hasMany('App.Spread'),
pagesCount: function() {
// Here is where i go wrong, i can get the length of spreads, but not access a spread to get the page length.
var spreadsLength = this.get('spreads.length');
var ret = 0;
this.get("spreads").forEach(function(spread)){
ret += spread.get('pages.length');
}
return ret;
}.property('spreads.@each.pages.length')
});
Note: Look at the property dependency i declared via property. Since the ComputedProperty depend on those paths, you need to declare them there.
回答2:
App.User = DS.Model.extend({
firstName: DS.attr('string'),
lastName: DS.attr('string'),
email: DS.attr('st App.User = DS.Model.extend({
firstName: DS.attr('string'),
lastName: DS.attr('string'),
email: DS.attr('string'),
phone: DS.attr('string'),
status: DS.attr('string', { defaultValue: 'new' }),
notes: DS.attr('string'),
// projects: DS.hasMany("project", {async: true}),
projectsCount: function() {
// alert(this.get('projects'));
return this.get('projects.length');
}.property('id'),
fullName: function() {
return this.get('firstName') + ' ' + this.get('lastName')
}.property('firstName', 'lastName')
}),
App.User.reopenClass({
valid: function(fields) {
return fields.firstName && fields.lastNameenter code here
}
});ring'),
phone: D App.User = DS.Model.extend({
firstName: DS.attr('string'),
lastName: DS.attr('string'),
email: DS.attr('string'),
phone: DS.attr('string'),
status: DS.attr('string', { defaultValue: 'new' }),
notes: DS.attr('string'),
// projects: DS.hasMany("project", {async: true}),
projectsCount: function() {
// alert(this.get('projects'));
return this.get('projects.length');
}.property('id'),
fullName: function() {
return this.get('firstName') + ' ' + this.get('lastName')
}.property('firstName', 'lastName')
}),
App.User.reopenClass({
valid: function(fields) { App.User = DS.Model.extend({
firstName: DS.attr('string'),
lastName: DS.attr('string'),
email: DS.attr('string'),
phone: DS.attr('string'),
status: DS.attr('string', { defaultValue: 'new' }),
notes: DS.attr('string'),
// projects: DS.hasMany("project", {async: true}),
projectsCount: function() {
// alert(this.get('projects'));
return this.get('projects.length');
}.property('id'),
fullName: function() {
return this.get('firstName') + ' ' + this.get('lastName')
}.property('firstName', 'lastName')
}),
App.User.reopenClass({
valid: function(fields) App.User = DS.Model.extend({
firstName: DS.attr('string'),
lastName: DS.attr('string'),
email: DS.attr('string'),
phone: DS.attr('string'),
status: DS.attr('string', { defaultValue: 'new' }),
notes: DS.attr('string'),
// projects: DS.hasMany("project", {async: true}),
projectsCount: function() {
// alert(this.get('projects'));
return this.get('projects.length');
}.property('id'),
fullName: function() {
return this.get('firstName') + ' ' + this.get('lastName')
}.property('firstName', 'lastName')
}),
App.User.reopenClass({
valid: function(fields) {
return fields.firstName && fields.lastNameenter code here
}
}); {
return fields.firstName && fields.lastNameenter code here
}
});
return fields.firstName && fields.lastNameenter code here
}
});S.attr('string'),
status: DS.attr('string', { defaultValue: 'new' }),
notes: DS.attr('string'),
// projects: DS.hasMany("project", {async: true}),
projectsCount: function() {
// alert(this.get('projects'));
return this.get('projects.length');
}.property('id'),
fullName: function() {
return this.get('firstName') + ' ' + this.get('lastName')
}.property('firstName', 'lastName')
}),
App.User.reopenClass({
valid: function(fields) {
return fields.firstName && fields.lastNameenter code here
}
});
App.User = DS.Model.extend({
firstName: DS.attr('string'),
lastName: DS.attr('string'),
email: DS.attr('string'), App.User = DS.Model.extend({
firstName: DS.attr('string'),
lastName: DS.attr('string'),
email: DS.attr('string'),
phone: DS.attr('string'),
status: DS.attr('string', { defaultValue: 'new' }),
notes: DS.attr('string'),
// projects: DS.hasMany("project", {async: true}),
projectsCount: function() {
// alert(this.get('projects'));
return this.get('projects.length');
}.property('id'),
fullName: function() {
return this.get('firstName') + ' ' + this.get('lastName')
}.property('firstName', 'lastName')
}),
App.User.reopenClass({
valid: function(fields) {
return fields.firstName && fields.lastNameenter code here
}
});
phone: DS.attr('string'),
status: DS.attr(' App.User = DS.Model.extend({
firstName: DS.attr('string'),
lastName: DS.attr('string'),
email: DS.attr('string'),
phone: DS.attr('string'),
status: DS.attr('string', { defaultValue: 'new' }),
notes: DS.attr('string'),
// projects: DS.hasMany("project", {async: true}),
projectsCount: function() {
// alert(this.get('projects'));
return this.get('projects.length');
}.property('id'),
fullName: function() {
return this.get('firstName') + ' ' + this.get('lastName')
}.property('firstName', 'lastName')
}),
App.User.reopenClass({
valid: function(fields) {
return fields.firstName && field App.User = DS.Model.extend({
firstName: DS.attr('string'),
lastName: DS.attr('string'),
email: DS.attr('string'),
phone: DS.attr('string'),
status: DS.attr('string', { defaultValue: 'new' }),
notes: DS.attr('string'),
// projects: DS.hasMany("project", {async: true}),
projectsCount: function() {
// alert(this.get('projects'));
return this.get('projects.length');
}.property('id'),
fullName: function() {
return this.get('firstName') + ' ' + this.get('lastName')
}.property('firstName', 'lastName')
}),
App.User.reopenClass({
valid: function(fields) {
return fields.firstName && fields.lastNameenter code here
}
});s.lastNameenter code here
}
});string', { defaultValue: 'new' }),
notes: DS.attr('string'),
// projects: DS.hasMany("project", {async: true}),
projectsCount: function() {
// alert(this.get('projects'));
return this.get('projects.length');
}.property('id'),
fullName: function() {
return this.get('firstName') + ' ' + this.get('lastName')
}.property('firstName', 'lastName')
}),
App.User.reopenClass({
valid: function(fields) {
return fields.firstName && fields.lastNameenter code here
}
});
来源：https://stackoverflow.com/questions/15951223/emberjs-unable-to-get-the-length-of-an-hasmany-array-two-levels-down