It sounds like you want to group the `MyObject` instances by `KeyedProperty` and put that grouping into a `Dictionary&lt;long,List&lt;MyObject&gt;&gt;`.  If so then try the following

    List&lt;MyObject&gt; list = ...;
    var map = list
      .GroupBy(x =&gt; x.KeyedProperty)
      .ToDictionary(x =&gt; x.Key, x =&gt; x.ToList());

You should use the [`ToLookup` extension method][1] on the [`Enumerable` class][2] like so:

    List&lt;MyObject&gt; list = ...;

    ILookup&lt;long, MyObject&gt; lookup = list.ToLookup(o =&gt; o.KeyedProperty);

If you want to place that in a dictionary, then you could use the [`ToDictionary` extension method][3], like so:

    IDictionary&lt;long, IEnumerable&lt;MyObject&gt;&gt; dictionary = lookup.ToDictionary(
        l =&gt; l.Key);


  [1]: http://msdn.microsoft.com/en-us/library/bb549073.aspx
  [2]: http://msdn.microsoft.com/en-us/library/system.linq.enumerable.aspx
  [3]: http://msdn.microsoft.com/en-us/library/bb549277.aspx

I found a way to get inherited members via  `class.getDeclaredFields();`
and acces to private members via `class.getFields()`
But i&#39;m looking for private inherited fields.
How can i achieve this?




Access to private inherited fields via reflection in Java

Can anybody tell me the reason for **failed binder transaction** error? I can see this error message in logcat.
I am getting this error while trying to put an bitmap dynamically in a widget...

Failed binder transaction when putting an bitmap dynamically in a widget

I have a 

    List&lt;MyObject&gt; 

that I retrieve from the database. However, I would like it keyed by a property in MyObject for grouping purposes. What is the best way with LINQ to cast my list to:

    Dictionary&lt;long, List&lt;MyObject&gt;&gt;

I have the following:

    myObjectList.ToDictionary(x =&gt; x.KeyedProperty)

But it returns:

    Dictionary&lt;long, MyObject&gt;

LINQ - Convert List to Dictionary with Value as List

I have a
<pre><code class="hljs language-php-template">List&#x3C;MyObject> 
</code></pre>
that I retrieve from the database. However, I would like it keyed by a property in MyObject for grouping purposes. What is the best way with LINQ to cast my list to:
<pre><code class="hljs language-swift">Dictionary&#x3C;long, List&#x3C;MyObject>>
</code></pre>
I have the following:
<pre><code class="hljs language-ini">myObjectList.ToDictionary(x => x.KeyedProperty)
</code></pre>
But it returns:
<pre><code class="hljs language-arduino">Dictionary&#x3C;long, MyObject>
</code></pre>

In C#, what is the difference between `ToUpper()` and `ToUpperInvariant()`?

Can you give an example where the results might be different? 

In C# what is the difference between ToUpper() and ToUpperInvariant()?

I created a &quot;Code Only&quot; POCO for use against an existing database using Entity Framework 4 and the CTP4.  When I run a query I get the error 

&gt;The model backing the &#39;xyzContext&#39; context has changed since the database was created. Either manually delete/update the database, or call Database.SetInitializer with an IDatabaseInitializer instance. For example, the RecreateDatabaseIfModelChanges strategy will automatically delete and recreate the database, and optionally seed it with new data.

I&#39;m unclear on why this is happening or what I can change.  I merely created the POCO, defined a simple DbContext, made a few tweaks, and then tried to run a simple query.  Since I&#39;m using &quot;Code Only&quot;, I&#39;m unaware of any configuration settings that need to be made. And I certainly don&#39;t want to recreate or delete the database since it&#39;s an existing database.

Thanks for any ideas.

Entity Framework Code Only error: the model backing the context has changed since the database was created

I would like to understand why you might want to use the `global::` prefix. In the following code, ReSharper is identifying it as redundant, and able to be removed:

![alt text][1]


  [1]: https://farm5.static.flickr.com/4141/4922038418_f6906070c3_o.png

Why use the global keyword in C#?

Say I have a `foreach` loop.

I have to do something with the first object of the loop that I don&#39;t have to do with any of the other objects.

How do I check if the item that&#39;s currently in the loop is the first object.


how do I check if an entity is the first element of a foreach loop

In the same solution, I have two projects: P1 and P2. How can I make use of a class of P1 in P2?

How to use a class from one C# project with another C# project

I&#39;ve found how to turn a DateTime into an [ISO 8601][1] format, but nothing on how to do the reverse in C#.

I have `2010-08-20T15:00:00Z`, and I want to turn it into a `DateTime` object.

I could separate the parts of the string myself, but that seems like a lot of work for something that is already an international standard.

  [1]: https://en.wikipedia.org/wiki/ISO_8601


How to create a .NET DateTime from ISO 8601 format

In &quot;C# 4 in a Nutshell&quot;, the author shows that this class can write 0 sometimes without `MemoryBarrier`, though I can&#39;t reproduce in my Core2Duo:

    public class Foo
    {
        int _answer;
        bool _complete;
        public void A()
        {
            _answer = 123;
            //Thread.MemoryBarrier();    // Barrier 1
            _complete = true;
            //Thread.MemoryBarrier();    // Barrier 2
        }
        public void B()
        {
            //Thread.MemoryBarrier();    // Barrier 3
            if (_complete)
            {
                //Thread.MemoryBarrier();       // Barrier 4
                Console.WriteLine(_answer);
            }
        }
    }

    private static void ThreadInverteOrdemComandos()
    {
        Foo obj = new Foo();

        Task.Factory.StartNew(obj.A);
        Task.Factory.StartNew(obj.B);

        Thread.Sleep(10);
    }

This need seems crazy to me. How can I recognize all possible cases that this can occur? I think that if processor changes order of operations, it needs to guarantee that the behavior doesn&#39;t change.

Do you bother to use Barriers?

Why we need Thread.MemoryBarrier()?

Acting on the answer to my [Select a model property using a lambda and not a string property name][1] question, wanting to add properties to a collection as follows: 

    var props = new ExportPropertyInfoCollection&lt;JobCard&gt;();
    props.Include(model =&gt; model.BusinessInstallNumber).Title(&quot;Install No&quot;).Width(64).KeepZeroPadding(true);
    props.Include(model =&gt; model.DeviceName).Title(&quot;Device&quot;).Width(70);
    props.Include(model =&gt; model.DateRequested).Title(&quot;Request Date&quot;).Format(&quot;{0:dd/MM/yyyy}&quot;).Width(83);

I wrote the following code in the `Include` method:

    public class PropertyCollection&lt;T&gt;
    {
        public void Include(Expression&lt;Func&lt;T, object&gt;&gt; expression)
        {
            var memberExpression = expression.Body as MemberExpression;
            if (memberExpression != null)
            {
                var pes = new ExportPropertyInfoBuilder {Property = new ExportPropertyInfo {Property = memberExpression.Member as PropertyInfo}};
                Properties.Add(pes.Property.Property.Name, pes.Property);
                return pes;
        }

However, on running the code, I found some of the lambdas yielded **MemberExpression** values as expected, but others yielded **UnaryExpression** values.  I had to change the first line of code to the following before I could add all my properties using lambdas:

    var memberExpression = expression.Body as MemberExpression ?? ((UnaryExpression) expression.Body).Operand as MemberExpression;

All the properties are &#39;simple&#39; types, i.e. string, DateTime, int, bool, etc. in a POCO business object.  They are decorated with several varying **DataAnnotations** attributes.

What causes some of the lambdas in my example to yield **MemberExpression** values and others **UnaryExpression** values?  In my example, the first **UnaryExpression** is on the third line, the **DateTime** property, but boolean properties also result in **UnaryExpressions**.


  [1]: https://stackoverflow.com/questions/3558974/select-a-model-property-using-a-lambda-and-not-a-string-property-name

Why are some object properties UnaryExpression and others MemberExpression?

I have some doubts over how Enumerators work, and LINQ. Consider these two simple selects:

    List&lt;Animal&gt; sel = (from animal in Animals 
                        join race in Species
                        on animal.SpeciesKey equals race.SpeciesKey
                        select animal).Distinct().ToList();

or

    IEnumerable&lt;Animal&gt; sel = (from animal in Animals 
                               join race in Species
                               on animal.SpeciesKey equals race.SpeciesKey
                               select animal).Distinct();

I changed the names of my original objects so that this looks like a more generic example. The query itself is not that important. What I want to ask is this:

    foreach (Animal animal in sel) { /*do stuff*/ }

1. I noticed that if I use `IEnumerable`, when I debug and inspect &quot;sel&quot;, which in that case is the IEnumerable, it has some interesting members: &quot;inner&quot;, &quot;outer&quot;, &quot;innerKeySelector&quot; and &quot;outerKeySelector&quot;, these last 2 appear to be delegates. The &quot;inner&quot; member does not have &quot;Animal&quot; instances in it, but rather &quot;Species&quot; instances, which was very strange for me. The &quot;outer&quot; member does contain &quot;Animal&quot; instances. I presume that the two delegates determine which goes in and what goes out of it?

2. I noticed that if I use &quot;Distinct&quot;, the &quot;inner&quot; contains 6 items (this is incorrect as only 2 are Distinct), but the &quot;outer&quot; does contain the correct values. Again, probably the delegated methods determine this but this is a bit more than I know about IEnumerable.

3. Most importantly, which of the two options is the best performance-wise?

The evil List conversion via `.ToList()`?

Or maybe using the enumerator directly?

If you can, please also explain a bit or throw some links that explain this use of IEnumerable.

IEnumerable vs List - What to Use? How do they work?

With extension methods, we can write handy LINQ operators which solve generic problems.

I want to hear which methods or overloads you are missing in the `System.Linq` namespace and how you implemented them.

Clean and elegant implementations, maybe using existing methods, are preferred.


What&#39;s your favorite LINQ to Objects operator which is not built-in?

I have 

`string[] pkgratio= &quot;1:2:6&quot;.Split(&#39;:&#39;);`

    var items = pkgratio.OrderByDescending(x =&gt; x);

I want to select the middle value and have come up with this. Is this a correct way to select the second value in an IEnumberable?

    pkgratio.Skip(1).Take(1).First();

LINQ - selecting second item in IEnumerable

Unfortunately the names of these methods make terrible search terms, and I&#39;ve been unable to find a good resource that explains the difference between these methods--as in when to use each.

Thanks.

Edit:

The sort of query that I&#39;m trying to fully understand is something like this:

    context.Authors.Where(a =&gt; a.Books.Any(b =&gt; b.BookID == bookID)).ToList();

And thanks to all who&#39;ve answered.

Content Type	Original Author	Original Content on Stackoverflow
Question	Brandon	View Question on Stackoverflow
Solution 1 - C#	JaredPar	View Answer on Stackoverflow
Solution 2 - C#	casperOne	View Answer on Stackoverflow

LINQ - Convert List to Dictionary with Value as List

C# Problem Overview

C# Solutions

Solution 1 - C#

Solution 2 - C#

Failed binder transaction when putting an bitmap dynamically in a widget

Access to private inherited fields via reflection in Java

Attributions