Lazy and Eager Loading in Entity Framework

We see that for “Timken eng” there are 2 in the location count. As we discussed, lazy loading is enabled by default. Let's now explain the output. Here the total 2 query is fireed in the DB. The first query is at the time of company loading and the next one is at the time of count loading within the foreach loop and the output is here.

Now, we will disable lazy loading in the application and we will check the behavior of the application. Here is the code for turning off lazy loading that was enabled by default:

Eager loading

And we see that the number of counts for “Timken Eng” is 0 in this case. Because only one query was fired and the query within the foreach was not executed, so the count value is 0.

So, to solve the problem, we can explicitly specify the table names that need to be loaded even when lazy loading is false. Here is the modified code:

static void Main(string[] args)

{

using (var ctx = new efDBEntities())

{

ctx.Configuration.LazyLoadingEnabled = false;

var company = ctx.companies.Include("company_location").Take(1).ToList<company>();

foreach (company c in company)

{

Console.WriteLine("Company Name:" + c.company_name);

Console.WriteLine("Location:" + c.company_location.Count);

}

}

Console.ReadLine();

}

We have now specified a table name “company_location” in the query within Include(), it implies that the table is also loaded at the time of query execution. If we run the code above, we will see that the count property is populated again.

Finally

It's always necessary to turn off lazy loading at the time of serialization of the resultant object otherwise it will throw an error. Thanks for reading, in our next article we will learn Explicit loading.