How do i remove a specific collection from my model in C#

Question

This is my model:

    public class ObsModel : BindableBase
    {


        private String _ObsName = string.Empty;
        public string ObsName
        {
            get { return this._ObsName; }
            set { this.SetProperty(ref this._ObsName, value); }
        }

        private String _ObsColor = string.Empty;
        public string ObsColor
        {
            get { return this._ObsColor; }
            set { this.SetProperty(ref this._ObsColor, value); }
        }

        private String _ObsValue = string.Empty;
        public string ObsValue
        {
            get { return this._ObsValue; }
            set { this.SetProperty(ref this._ObsValue, value); }
        }
}

I can then populate my model using this object.

ObservableCollection<ObsModel> LastObsResults = new ObservableCollection<ObsModel>();

But how can I remove a particular collection if I have for example the observation name as a string variable by using the code below?

LatsObsResults.Remove( What DO I PUT HERE);

Overide the `Equals` and `GetHashCode` methods that compare `_ObsName — KV Prajapati, Apr 22 '15 at 13:45
Ok just to make sure, you have the `ObsModel.ObsName` and want to remove the corresponding `ObsModels` with that name? — ryanyuyu, Apr 22 '15 at 13:46
yes I want to remove everything associated with that obsname — user3929914, Apr 22 '15 at 13:52
Possible duplication (with solution): http://stackoverflow.com/questions/5118513/removeall-for-observablecollections This also avoids recreate the collection and allow you to remove one or a list of elements. — Max Bündchen, Apr 22 '15 at 13:59

score 1 · Accepted Answer · answered Apr 22 '15 at 13:59

1

You remove an object from the collection by passing in the object to remove. This can be done through Linq like so:

LastObsResults.Remove(LastObsResults.FirstOrDefault(obs => obs.ObsName == name));

answered Apr 22 '15 at 13:59

Cros

4,367
9
41
47

sorry but I am new to this what is obs supposed to be based on my code – user3929914 Apr 22 '15 at 14:05

score 0 · Answer 2 · answered Apr 22 '15 at 13:56

This solution uses LINQ .Where to produce the valid subset of your results, then assigns that subset to a new ObsevableCollection. I am using the constructor that accepts an IEnumerable.

var validSubset = LastObsResults.Where(obs => obs.ObsName != name);
LastObsResults = new ObservableCollection<ObsModel>(validSubset);

score 0 · Answer 3 · answered Apr 22 '15 at 13:58

Try this:

var lastObsUpdated = LastObsResults.Except(model => model.ObsName == "Whatever")
                                   .ToList()
                                   .AsObservable();

This will create you an updated ObservableCollection with all but a named item.

score -1 · Answer 4 · answered Apr 22 '15 at 14:45

If you want to remove all items you can use this:

LastObsResults .Clear();

If you want to create your own extension method you could do something like this:

public static class ObservableCollectionExtensions
{
    public static int Remove<T>(
        this ObservableCollection<T> coll, Func<T, bool> condition)
    {
        var itemsToRemove = coll.Where(condition).ToList();

        foreach (var item in itemsToRemove)
        {
            coll.Remove(item);
        }

        return itemsToRemove.Count;
    }
}

With the extension above you can remove all items that match the condition passed. Example:

LastObsResults.Remove(x=> x.ObsName == myName);

And finally, you could use the existing collection.Remove() method but make sure you use it like described here to avoid a very common issue.

How do i remove a specific collection from my model in C#

4 Answers4