Question

If I use entity framework with linq to sql to query it and I have an object Person but I only need two properties of that object, what’s in memory will be load, the entire object ?

Example :

I got the entity Person with properties : Name, Age, Address, Country, Language …

I only need to use the property Name and Age. So I got no need to load the address, country and other property … what will be in memory and what type of query will be ask to SQL ?

If my Linq query is :

public IQueryable<Person> FindAllPersons()
{
    return from person in db.Persons
           select person;
}

And later in code I only call the Name and Age property of each Person in the list.

Answer 1

You can query for only the fields you need.

Like so,

public IQueryable<Person> FindAllPersons()
{
    return from person in db.Persons
           select new Person(){Name = person.Name, Age = person.Age};
}