SelectMany in LINQ
Written By:- Isha Malhotra
What is SelectMany
SelectMany projects each elements result into one sequence i.e IEnumerable<T>.
Earlier we used select operator to select data from linq.
Example of SelectMany
Take a class in which one filed is another data source like array, list etc. as I have created contact number as int array.
public class employee
{
public int id { get; set; }
public string name { get; set; }
public string dept { get; set; }
public Int64[] contact { get; set; }
}
Now I have created list to add data
List<employee> emp = new List<employee>()
{
new employee(){ id=101, name="isha", dept="hr", contact=new Int64[]{9787878787, 8989898980}},
new employee(){ id=102, name="neha", dept="sales", contact=new Int64[]{9786868687, 8989898986}},
new employee(){ id=103, name="pooja", dept="hr", contact=new Int64[]{9787888087, 8989898984}},
new employee(){ id=104, name="rahul", dept="development", contact=new Int64[]{1234567890, 8989898987}}
};
Now I need to fetch the contact numbers which is stored in the format of array.
So result set will be like IEnumerable<Int64[]>
I need to use two loop to traverse this result.
Response.Write("Result of Select Operator <br>");
IEnumerable<Int64[]> res= emp.Select(x => x.contact);
foreach (Int64[] data in res)
{
foreach (Int64 contact in data)
{
Response.Write(contact + "<br>");
}
}
Now use selectMany operator in which it projects all elements into single sequence
Response.Write("Result of Select Many <br>");
IEnumerable<Int64> res_selectmany = emp.SelectMany(x => x.contact);
foreach (Int64 contact in res_selectmany)
{
Response.Write(contact + "<br>");
}
Now execute the code
Figure 2
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