Update specific object in array

Question

I have a DataTable and an array of objects that I loop through.

For each row in a data table, I search through my collection of objects with Linq, and if found, that object needs to be updated. But how do I refresh my collection without reloading it from the database?

Car[] mycars = Cars.RetrieveCars(); //This is my collection of objects

//Iterate through Cars and find a match 
using (DataTable dt = data.ExecuteDataSet(@"SELECT * FROM aTable").Tables[0])
{
    foreach (DataRow dr in dt.Rows) //Iterate through Data Table 
         {
            var found = (from item in mycars 
                         where item.colour == dr["colour"].ToString()
                            && item.updated == false
                         select item).First();
             if (found == null)
                //Do something
             else
             {
                  found.updated = true;
                  Cars.SaveCar(found);
                  //HERE: Now here I would like to refresh my collection (mycars) so that the LINQ searches on updated data.
                  //Something like mycars[found].updated = true
                  //But obviously mycars can only accept int, and preferably I do not want to reload from the database for performance reasons.
             }

How else can I search and update a single item in the array?

As an aside, I think you mean if (found == null)

Jon Skeet
– Jon Skeet

2013-08-02 12:23:05 +00:00
Commented Aug 2, 2013 at 12:23 — Jon Skeet
– Jon Skeet, Commented Aug 2, 2013 at 12:23

Jon Skeet · Accepted Answer · 2013-08-02 12:21:40Z

8

You don't need to update your collection - assuming Car is a class, you've already updated the object that the array refers to by setting found.updated to true.

Don't forget that the array only contains references - so the found reference is the same reference which is in the array; updating the object via either variable will result in the change being visible via the other one.

answered Aug 2, 2013 at 12:21

Jon Skeet

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2 Comments

Cameron Castillo Over a year ago

References you say. Interesting. Will test it. Thanks.

Jon Skeet Over a year ago

@user1208908: Yes. This is part of the core of C# - it's really important that you understand how objects and references work in C#. See pobox.com/~skeet/csharp/references.html

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