CODEWITHSUNDEEP
c#xamarinxamarin.forms
Josh Isaacs
Josh Isaacs

Reputation: 87

Sorting an ObservableCollection of Objects by Properties in Xamarin Forms

I am trying to sort an observable collection of objects by one of their properties in Xamarin Forms.

It seems like the following code should work, but it does not. I am trying to learn as much as I can, so I am very interested why it does not. I'm certain I can copy and paste the solution somewhere, but I've yet to find an answer that explains the why.

using System;
using System.Collections.Generic;
using System.Collections.ObjectModel;
using System.Linq;
using Xamarin.Forms;
using Xamarin.Forms.Internals;

namespace engME
{
    public partial class YourFullNamesListPage : ContentPage
    {
        ObservableCollection<NameObject> _nameList {get; } = MainPage.NameList;
        public YourFullNamesListPage()
        {
            InitializeComponent();
            _nameList = _nameList.OrderByDescending(a => a.Name);
            FullNamesList.ItemsSource= _nameList;
        }
    }
}

Upvotes: 0

Views: 4241

Answers (2)

FreakyAli
FreakyAli

Reputation: 16479

Well first of all i don't think your property should be like 

ObservableCollection<NameObject> _nameList {get; } = MainPage.NameList;

Since you have to made changes in it later i would suggest you have get as well as set in your property(Since you might have to use it in some other class):

ObservableCollection<NameObject> _nameList {get; set; } = MainPage.NameList;

Then to set your order you do it something like this:

 public YourFullNamesListPage()
    {
        InitializeComponent();
        _nameList =  new ObservableCollection<NameObject>(_nameList.OrderByDescending(x => x.Name));
        FullNamesList.ItemsSource= _nameList;
    }

Where the below is of the type System.Linq.IOrderedEnumerable<T> and hence you need to convert it to an observable collection by wrapping it into one.

_nameList.OrderByDescending(x => x.Name)

And then you are good to go Revert in case of queries.

Upvotes: 1

christian
christian

Reputation: 114

Your _nameList is getonly, thus the following assignment wont change it at all:

 _nameList = ObservableCollection<NameObject>(MainPage.NameList.OrderByDescending(a => a.Name));

Upvotes: 0

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