LINQ: Sequence Contains No Elements:First()


LINQ: Sequence Contains No Elements:

The InvalidOperationException:Sequence contains no lelments exception will occur whenever we will try to retrive data from table in database doesn’t contain no elements… so whenever we are trying to get data it does not match our query, this error will occur.

 What is First() in Linq:

Whenever we want to select first record only from list of records we will use this first() method as follows

Var x = (from n in Contextorentity.TableName select n).first();

If we want to select last record only from list of records we will use Last() method as follows

Var x = (from n in Contextorentity.TableName select n).first();

Without where Condition:

 var x = (from n in Contextorentity.TableName select n).first();

if the above select query contains no records in it it will return error like sequence contain no elements

with where condition:

if we are using any where condition in our query as follows

var x = (from n in Contextorentity.Employee where n.EmpId == 100  select n).first();

if no record matches with this query it returns error because the first method should select single record from list only, so if no list founds it will returns error.

Remidy:

We have solution for this error in linq only that is,

Instead of using First() method we can use FirstOrDefault() method.

What is FirstOrDefault() Method:

Firstordefault() method will also select single record from list of records, if no records found it will returns null value, so error won’t come…

 

Thanks

………………..Happy Coding………………….

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