Strange behavior of INCLUDE in Entity Framework

Question

This works:

using (var dbContext = new SmartDataContext())
{
    dbContext.Configuration.ProxyCreationEnabled = false;

    var query = dbContext.EntityMasters.OfType<Person>();
    if (includeAddress)
        query.Include(p => p.Addresses);
    if (includeFiles)
        query.Include(p => p.FileMasters);

    output.Entity = query.Include(s=>s.Addresses).FirstOrDefault<Person>(e => e.EntityId == id);
}

while this doesn't:

using (var dbContext = new SmartDataContext())
{
    dbContext.Configuration.ProxyCreationEnabled = false;

    var query = dbContext.EntityMasters.OfType<Person>();
    if (includeAddress)
        query.Include(p => p.Addresses);
    if (includeFiles)
        query.Include(p => p.FileMasters);

    output.Entity = query.FirstOrDefault<Person>(e => e.EntityId == id);
}

I am trying to include Addresses, Files based on boolean flags coming from function. However it seems, EF not including them when using IF condition.

This is related to my previous question which actually worked using Include.

Rule of thumb: If you have to say "Edit" to put in an edit, then you don't really need the edit. — Robert Harvey
– Robert Harvey, Commented Jul 9, 2015 at 21:13

Aducci · Accepted Answer · 2015-07-09 21:16:42Z

2

You need to assign the result of Include back to query

query = query.Include(p => p.Addresses);

answered Jul 9, 2015 at 21:16

Aducci

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Comments

Roy T. · Accepted Answer · 2015-07-09 21:00:36Z

0

Entity framework's 'Include' function only works when it is connected to the entire linq query that was looking up the entity. This is because the linq query is actually a form of Expression that can be inspected as a whole before it is executed.

In the second example there the Person object is already detached from the database so EF has no information on which table Person came from and how it should join Person with the address table to get the results you want.

If you turn on dynamic proxy generation EF is able to keep track of the relation between the entity and the database. However, I'm not sure if this will make the include statement work.

answered Jul 9, 2015 at 21:00

Roy T.

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1 Comment

Shantanu Gupta Over a year ago

I am not convinced with your statement. When you say Person object is already detached from database, what do you mean? Its a IQueryable object and query variable is holding the query that's being modified.

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