Get value from C# lookup

c# lookup example
c# lookup get all values
c# lookup vs dictionary
c# lookup table
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c# tolookup
c# lookup multiple values
c# lookup key not found

I'm interested in how to get value from C# lookup structure.

Example:

var myLookup = (Lookup<string, int>)data.Rows.Cast<DataRow>().ToLookup(row => row["Name"], row => row["Id"]);

foreach (var myLookupItem in myLookup)
                    {
                        Debug.WriteLine("Name: " + myLookupItem.Key);
                        Debug.WriteLine("Id: " + myLookupItem.ToString());
                    }

Problem is that the

myLookupItem.ToString()

doesn't display actual value, instead only System.Linq.Lookup2[System.String,System.Int32] is displayed.

Later on, I should get the lookup value using lambda:

 int lookupValue = myLookup.Where(x => x.Key == "Test").Select(x => x).FirstOrDefault());

but this also gives the same as above.

Please advise how to achieve this.

Thanks in advance.

That's because the lookup item is a collection. You can see every value of the lookup like this:

foreach (var myLookupItem in myLookup)
{
    Debug.WriteLine("Key: " + myLookupItem.Key);
    foreach (var myLookupValue in myLookupItem)
    {
        Debug.WriteLine("Value: " + myLookupValue);
    }
}

Lookup<TKey,TElement> Class, Several times in my project I need to convert a list to dictionary, packing different elements in dictionary and return it to user as key, value pair in� His code dumps the lookup values from the meta into dictionaries. If you need the values from an entity, then I would suggest loading the entity and reading it. Below is an example of reading a lookup field. It assumes you have ORGANIZATION set in a string in the class.

"I do not think it means what you think it means."

A Lookup (from MSDN):

Represents a collection of keys each mapped to one or more values.

i.e. it groups them (even if these groups are singular).

It looks like you want to use something like a Dictionary instead of a Lookup. In the case of a Dictionary. You can use the ToDictionary() extension method instead of the ToLookup() extension method. You'd then use key and value on the dictionary.

Lookup In LINQ, We never, ever get KeyNotFound exception while using ILookup Although you can Count all keys with values in your Lookup or check if it� We never, ever get KeyNotFound exception while using ILookup indexer, worst case scenario you just end with empty Enumerable. Although you can Count all keys with values in your Lookup or check if it contains some key. Here’s interface which is being implemented by Lookup class implementation.

int lookupValue = myLookup.Where(x => x.Key == "Test").SelectMany(x => x).FirstOrDefault())

LookUp class in C# – have you ever tried it? – Hryniewski.NET, All groupings are accessed and enumerated. Note: The lambda expression in this example specifies that the lookup value for each string is the string's length. The specified seed value is used as the initial accumulator value, and the specified function is used to select the result value. All<TSource>(IEnumerable<TSource>, Func<TSource,Boolean>) Determines whether all elements of a sequence satisfy a condition.

C# ToLookup Method (Get ILookup), C# program that uses Dictionary, Add, Initializer and Count using System; using System.Collections. This is often the most efficient lookup method. As the name We can use the value we access without getting it a second time. C# program� Later on, I should get the lookup value using lambda: int lookupValue = myLookup.Where(x => x.Key == "Test").Select(x => x).FirstOrDefault()); but this also gives the same as above. Please advise how to achieve this.

C# Dictionary Examples, C# provides another Collection type called Lookup as a part of .NET Framework 3.5 which maps keys into a collection of values. This tip is all about using For More information Read this article from MSDN. Hope this helps ! The Lookup columns (SPFieldLookup) can have multiple values or just single value based on the AllowMultipleValues property. During creating a new Lookup column, If the AllowMultipleValues is checked, the column is multiple values; else, it's a single value.

Maps Keys to a Collection of Values using Lookup Collection, Count) and you can access the items with [value]. When you look up a key that does not exist in the Lookup, you don't get a KeyNotFound-� C# ToLookup Method (Get ILookup) First, this example uses an input string array of 3 string elements. The ToLookup method receives a Func delegate. This is specified as a lambda expression.

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