EF Core returns null relations until direct access

I have some models like those below:

public class Mutant

{

    public long Id { get; set; }

    ...



    // Relations

    public long OriginalCodeId { get; set; }

    public virtual OriginalCode OriginalCode { get; set; }

    public int DifficultyLevelId { get; set; }

    public virtual DifficultyLevel DifficultyLevel { get; set; }

}

and

public class OriginalCode

{

    public long Id { get; set; }

    ...



    // Relations

    public virtual List<Mutant> Mutants { get; set; }

    public virtual List<OriginalCodeInputParameter> OriginalCodeInputParameters { get; set; }

}

and in the OnModelCreating of DBContext I made the relations like these:

        modelBuilder.Entity<Mutant>()

            .HasOne(m => m.OriginalCode)

            .WithMany(oc => oc.Mutants)

            .HasForeignKey(m => m.OriginalCodeId)

            .OnDelete(Microsoft.EntityFrameworkCore.Metadata.DeleteBehavior.Restrict);



        modelBuilder.Entity<Mutant>()

            .HasOne(m => m.DifficultyLevel)

            .WithMany(dl => dl.Mutants)

            .HasForeignKey(m => m.DifficultyLevelId)

            .OnDelete(Microsoft.EntityFrameworkCore.Metadata.DeleteBehavior.Restrict);

now when I request for Mutants, the OriginalCode is null:

Null OriginalCode

but as soon as I request for OriginalCodes like below:

OriginalCodes

then the OriginalCode field of the mutants will be not null:

Filled Object

What is the reason and how could I fix it?

edited Dec 13 '18 at 4:31

Cœur

17.4k9103145

asked Feb 19 '17 at 13:03

ConductedClever

1,2381135

add a comment |

I have some models like those below:

public class Mutant

{

    public long Id { get; set; }

    ...



    // Relations

    public long OriginalCodeId { get; set; }

    public virtual OriginalCode OriginalCode { get; set; }

    public int DifficultyLevelId { get; set; }

    public virtual DifficultyLevel DifficultyLevel { get; set; }

}

and

public class OriginalCode

{

    public long Id { get; set; }

    ...



    // Relations

    public virtual List<Mutant> Mutants { get; set; }

    public virtual List<OriginalCodeInputParameter> OriginalCodeInputParameters { get; set; }

}

and in the OnModelCreating of DBContext I made the relations like these:

        modelBuilder.Entity<Mutant>()

            .HasOne(m => m.OriginalCode)

            .WithMany(oc => oc.Mutants)

            .HasForeignKey(m => m.OriginalCodeId)

            .OnDelete(Microsoft.EntityFrameworkCore.Metadata.DeleteBehavior.Restrict);



        modelBuilder.Entity<Mutant>()

            .HasOne(m => m.DifficultyLevel)

            .WithMany(dl => dl.Mutants)

            .HasForeignKey(m => m.DifficultyLevelId)

            .OnDelete(Microsoft.EntityFrameworkCore.Metadata.DeleteBehavior.Restrict);

now when I request for Mutants, the OriginalCode is null:

Null OriginalCode

but as soon as I request for OriginalCodes like below:

OriginalCodes

then the OriginalCode field of the mutants will be not null:

Filled Object

What is the reason and how could I fix it?

edited Dec 13 '18 at 4:31

Cœur

17.4k9103145

asked Feb 19 '17 at 13:03

ConductedClever

1,2381135

add a comment |

I have some models like those below:

public class Mutant

{

    public long Id { get; set; }

    ...



    // Relations

    public long OriginalCodeId { get; set; }

    public virtual OriginalCode OriginalCode { get; set; }

    public int DifficultyLevelId { get; set; }

    public virtual DifficultyLevel DifficultyLevel { get; set; }

}

and

public class OriginalCode

{

    public long Id { get; set; }

    ...



    // Relations

    public virtual List<Mutant> Mutants { get; set; }

    public virtual List<OriginalCodeInputParameter> OriginalCodeInputParameters { get; set; }

}

and in the OnModelCreating of DBContext I made the relations like these:

        modelBuilder.Entity<Mutant>()

            .HasOne(m => m.OriginalCode)

            .WithMany(oc => oc.Mutants)

            .HasForeignKey(m => m.OriginalCodeId)

            .OnDelete(Microsoft.EntityFrameworkCore.Metadata.DeleteBehavior.Restrict);



        modelBuilder.Entity<Mutant>()

            .HasOne(m => m.DifficultyLevel)

            .WithMany(dl => dl.Mutants)

            .HasForeignKey(m => m.DifficultyLevelId)

            .OnDelete(Microsoft.EntityFrameworkCore.Metadata.DeleteBehavior.Restrict);

now when I request for Mutants, the OriginalCode is null:

Null OriginalCode

but as soon as I request for OriginalCodes like below:

OriginalCodes

then the OriginalCode field of the mutants will be not null:

Filled Object

What is the reason and how could I fix it?

edited Dec 13 '18 at 4:31

Cœur

17.4k9103145

asked Feb 19 '17 at 13:03

ConductedClever

1,2381135

I have some models like those below:

public class Mutant

{

    public long Id { get; set; }

    ...



    // Relations

    public long OriginalCodeId { get; set; }

    public virtual OriginalCode OriginalCode { get; set; }

    public int DifficultyLevelId { get; set; }

    public virtual DifficultyLevel DifficultyLevel { get; set; }

}

and

public class OriginalCode

{

    public long Id { get; set; }

    ...



    // Relations

    public virtual List<Mutant> Mutants { get; set; }

    public virtual List<OriginalCodeInputParameter> OriginalCodeInputParameters { get; set; }

}

and in the OnModelCreating of DBContext I made the relations like these:

        modelBuilder.Entity<Mutant>()

            .HasOne(m => m.OriginalCode)

            .WithMany(oc => oc.Mutants)

            .HasForeignKey(m => m.OriginalCodeId)

            .OnDelete(Microsoft.EntityFrameworkCore.Metadata.DeleteBehavior.Restrict);



        modelBuilder.Entity<Mutant>()

            .HasOne(m => m.DifficultyLevel)

            .WithMany(dl => dl.Mutants)

            .HasForeignKey(m => m.DifficultyLevelId)

            .OnDelete(Microsoft.EntityFrameworkCore.Metadata.DeleteBehavior.Restrict);

now when I request for Mutants, the OriginalCode is null:

Null OriginalCode

but as soon as I request for OriginalCodes like below:

OriginalCodes

then the OriginalCode field of the mutants will be not null:

Filled Object

What is the reason and how could I fix it?

entity-framework-core

edited Dec 13 '18 at 4:31

Cœur

17.4k9103145

asked Feb 19 '17 at 13:03

ConductedClever

1,2381135

edited Dec 13 '18 at 4:31

Cœur

17.4k9103145

asked Feb 19 '17 at 13:03

ConductedClever

1,2381135

edited Dec 13 '18 at 4:31

Cœur

17.4k9103145

edited Dec 13 '18 at 4:31

Cœur

17.4k9103145

edited Dec 13 '18 at 4:31

Cœur

17.4k9103145

asked Feb 19 '17 at 13:03

ConductedClever

1,2381135

asked Feb 19 '17 at 13:03

ConductedClever

1,2381135

asked Feb 19 '17 at 13:03

ConductedClever

1,2381135

add a comment |

1 Answer
1

active

oldest

votes

The reason is explained in the Loading Related Data section of the EF Core documentation.

The first behavior is because EF Core currently does not support lazy loading, so normally you'll get null for navigation properties until you specifically load them via eager or explicit loading. However, the Eager loading section contains the following:

Tip

Entity Framework Core will automatically fix-up navigation properties to any other entities that were previously loaded into the context instance. So even if you don't explicitly include the data for a navigation property, the property may still be populated if some or all of the related entities were previously loaded.

which explains why the navigation property is not null in the second case.

Now, I'm not sure which of the two behaviors do you want to fix, so will try to address both.

The first behavior can be "fixed" by using one of the currently available methods for loading related data, for instance eager loading:

var mutants = db.Mutants.Include(m => m.OriginalCode).ToList();

The second behavior is "by design" and cannot be controlled. If you want to avoid it, make sure to use fresh new DbContext instance just for executing a single query to retry the data needed.

Update: Starting with v2.1, EF Core supports Lazy Loading. However it's not enabled by default, so in order to utilize it one should mark all navigation properties virtual, install Microsoft.EntityFrameworkCore.Proxies and enable it via UseLazyLoadingProxies call, or utilize Lazy-loading without proxies - both explained with examples in the EF Core documentation.

edited Jul 9 '18 at 18:02

answered Feb 19 '17 at 15:24

Ivan Stoev

100k770125

1

As you could guess I want to control the first behavior. But there is still a big question. This way you mentioned, I should explicitly address the relations to be filled, true?
– ConductedClever
Feb 19 '17 at 15:51

Indeed. You have to specify each one you want to be "included" using several Include / ThenInclude methods. AFAIK there are some plans for making this automatically in the future, but for now that's the only option.
– Ivan Stoev
Feb 19 '17 at 16:02

What about guessing, one never knows - for instance see a few question before yours in EF Core tag - Can I stop Entity Framework Core from populating my result with partial data? :)
– Ivan Stoev
Feb 19 '17 at 16:08

1

:) Thanks. Very Helpfull answer.
– ConductedClever
Feb 19 '17 at 16:50

1

Now EF Core support lazy loading: docs.microsoft.com/en-us/ef/core/querying/…
– Pejman.Nik
Apr 22 '18 at 13:41

|
show 2 more comments

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The reason is explained in the Loading Related Data section of the EF Core documentation.

Tip

Entity Framework Core will automatically fix-up navigation properties to any other entities that were previously loaded into the context instance. So even if you don't explicitly include the data for a navigation property, the property may still be populated if some or all of the related entities were previously loaded.

which explains why the navigation property is not null in the second case.

Now, I'm not sure which of the two behaviors do you want to fix, so will try to address both.

The first behavior can be "fixed" by using one of the currently available methods for loading related data, for instance eager loading:

var mutants = db.Mutants.Include(m => m.OriginalCode).ToList();

The second behavior is "by design" and cannot be controlled. If you want to avoid it, make sure to use fresh new DbContext instance just for executing a single query to retry the data needed.

edited Jul 9 '18 at 18:02

answered Feb 19 '17 at 15:24

Ivan Stoev

100k770125

1

As you could guess I want to control the first behavior. But there is still a big question. This way you mentioned, I should explicitly address the relations to be filled, true?
– ConductedClever
Feb 19 '17 at 15:51

Indeed. You have to specify each one you want to be "included" using several Include / ThenInclude methods. AFAIK there are some plans for making this automatically in the future, but for now that's the only option.
– Ivan Stoev
Feb 19 '17 at 16:02

What about guessing, one never knows - for instance see a few question before yours in EF Core tag - Can I stop Entity Framework Core from populating my result with partial data? :)
– Ivan Stoev
Feb 19 '17 at 16:08

1

:) Thanks. Very Helpfull answer.
– ConductedClever
Feb 19 '17 at 16:50

1

Now EF Core support lazy loading: docs.microsoft.com/en-us/ef/core/querying/…
– Pejman.Nik
Apr 22 '18 at 13:41

|
show 2 more comments

The reason is explained in the Loading Related Data section of the EF Core documentation.

Tip

Entity Framework Core will automatically fix-up navigation properties to any other entities that were previously loaded into the context instance. So even if you don't explicitly include the data for a navigation property, the property may still be populated if some or all of the related entities were previously loaded.

which explains why the navigation property is not null in the second case.

Now, I'm not sure which of the two behaviors do you want to fix, so will try to address both.

The first behavior can be "fixed" by using one of the currently available methods for loading related data, for instance eager loading:

var mutants = db.Mutants.Include(m => m.OriginalCode).ToList();

The second behavior is "by design" and cannot be controlled. If you want to avoid it, make sure to use fresh new DbContext instance just for executing a single query to retry the data needed.

edited Jul 9 '18 at 18:02

answered Feb 19 '17 at 15:24

Ivan Stoev

100k770125

1

As you could guess I want to control the first behavior. But there is still a big question. This way you mentioned, I should explicitly address the relations to be filled, true?
– ConductedClever
Feb 19 '17 at 15:51

Indeed. You have to specify each one you want to be "included" using several Include / ThenInclude methods. AFAIK there are some plans for making this automatically in the future, but for now that's the only option.
– Ivan Stoev
Feb 19 '17 at 16:02

What about guessing, one never knows - for instance see a few question before yours in EF Core tag - Can I stop Entity Framework Core from populating my result with partial data? :)
– Ivan Stoev
Feb 19 '17 at 16:08

1

:) Thanks. Very Helpfull answer.
– ConductedClever
Feb 19 '17 at 16:50

1

Now EF Core support lazy loading: docs.microsoft.com/en-us/ef/core/querying/…
– Pejman.Nik
Apr 22 '18 at 13:41

|
show 2 more comments

The reason is explained in the Loading Related Data section of the EF Core documentation.

Tip

Entity Framework Core will automatically fix-up navigation properties to any other entities that were previously loaded into the context instance. So even if you don't explicitly include the data for a navigation property, the property may still be populated if some or all of the related entities were previously loaded.

which explains why the navigation property is not null in the second case.

Now, I'm not sure which of the two behaviors do you want to fix, so will try to address both.

The first behavior can be "fixed" by using one of the currently available methods for loading related data, for instance eager loading:

var mutants = db.Mutants.Include(m => m.OriginalCode).ToList();

The second behavior is "by design" and cannot be controlled. If you want to avoid it, make sure to use fresh new DbContext instance just for executing a single query to retry the data needed.

edited Jul 9 '18 at 18:02

answered Feb 19 '17 at 15:24

Ivan Stoev

100k770125

The reason is explained in the Loading Related Data section of the EF Core documentation.

Tip

Entity Framework Core will automatically fix-up navigation properties to any other entities that were previously loaded into the context instance. So even if you don't explicitly include the data for a navigation property, the property may still be populated if some or all of the related entities were previously loaded.

which explains why the navigation property is not null in the second case.

Now, I'm not sure which of the two behaviors do you want to fix, so will try to address both.

The first behavior can be "fixed" by using one of the currently available methods for loading related data, for instance eager loading:

var mutants = db.Mutants.Include(m => m.OriginalCode).ToList();

The second behavior is "by design" and cannot be controlled. If you want to avoid it, make sure to use fresh new DbContext instance just for executing a single query to retry the data needed.

edited Jul 9 '18 at 18:02

answered Feb 19 '17 at 15:24

Ivan Stoev

100k770125

edited Jul 9 '18 at 18:02

answered Feb 19 '17 at 15:24

Ivan Stoev

100k770125

answered Feb 19 '17 at 15:24

Ivan Stoev

100k770125

answered Feb 19 '17 at 15:24

Ivan Stoev

100k770125

1

As you could guess I want to control the first behavior. But there is still a big question. This way you mentioned, I should explicitly address the relations to be filled, true?
– ConductedClever
Feb 19 '17 at 15:51

Indeed. You have to specify each one you want to be "included" using several Include / ThenInclude methods. AFAIK there are some plans for making this automatically in the future, but for now that's the only option.
– Ivan Stoev
Feb 19 '17 at 16:02

What about guessing, one never knows - for instance see a few question before yours in EF Core tag - Can I stop Entity Framework Core from populating my result with partial data? :)
– Ivan Stoev
Feb 19 '17 at 16:08

1

:) Thanks. Very Helpfull answer.
– ConductedClever
Feb 19 '17 at 16:50

1

Now EF Core support lazy loading: docs.microsoft.com/en-us/ef/core/querying/…
– Pejman.Nik
Apr 22 '18 at 13:41

|
show 2 more comments

1

As you could guess I want to control the first behavior. But there is still a big question. This way you mentioned, I should explicitly address the relations to be filled, true?
– ConductedClever
Feb 19 '17 at 15:51

Indeed. You have to specify each one you want to be "included" using several Include / ThenInclude methods. AFAIK there are some plans for making this automatically in the future, but for now that's the only option.
– Ivan Stoev
Feb 19 '17 at 16:02

What about guessing, one never knows - for instance see a few question before yours in EF Core tag - Can I stop Entity Framework Core from populating my result with partial data? :)
– Ivan Stoev
Feb 19 '17 at 16:08

1

:) Thanks. Very Helpfull answer.
– ConductedClever
Feb 19 '17 at 16:50

1

Now EF Core support lazy loading: docs.microsoft.com/en-us/ef/core/querying/…
– Pejman.Nik
Apr 22 '18 at 13:41

As you could guess I want to control the first behavior. But there is still a big question. This way you mentioned, I should explicitly address the relations to be filled, true?
– ConductedClever
Feb 19 '17 at 15:51

Indeed. You have to specify each one you want to be "included" using several Include / ThenInclude methods. AFAIK there are some plans for making this automatically in the future, but for now that's the only option.
– Ivan Stoev
Feb 19 '17 at 16:02

What about guessing, one never knows - for instance see a few question before yours in EF Core tag - Can I stop Entity Framework Core from populating my result with partial data? :)
– Ivan Stoev
Feb 19 '17 at 16:08

:) Thanks. Very Helpfull answer.
– ConductedClever
Feb 19 '17 at 16:50

Now EF Core support lazy loading: docs.microsoft.com/en-us/ef/core/querying/…
– Pejman.Nik
Apr 22 '18 at 13:41

|
show 2 more comments

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