Why EF navigation property return null?

asp.net asp.net-mvc c# entity-framework

Question

I have two model 1)

public class Indicator
{
    public long ID { get; set; }
    public string Name { get; set; }
    public int MaxPoint { get; set; }
    public string Comment { get; set; }
    public DateTime DateChanged { get; set; }
    public DateTime DateCreated { get; set; }

    public virtual IList<CalculationType> CalculationTypes { get; set; }
    public virtual IList<TestEntity> TestEntitys { get; set; }
    public virtual IndicatorGroup IndicatorGroup { get; set; }
}

2)

public class CalculationType
{
    public long ID { get; set; }
    public string UnitName { get; set; }
    public int Point { get; set; }
    public DateTime DateCreated { get; set; }
    public DateTime DateChanged { get; set; }

    public virtual Indicator Indicator { get; set; }
    public virtual IList<Сalculation> Calculations { get; set; }
}

I executing this code

var indicator = DataContext.Indicators.FirstOrDefault(i => i.ID == indicatorID);
var test = DataContext.CalculationTypes.FirstOrDefault();

first line return null on navigation property CalculationTypes enter image description here

Second line return empty collection.enter image description here Why?

UPDATE snapshot database enter image description hereenter image description here project link https://github.com/wkololo4ever/Stankin

added Calculation

    public class Сalculation
{
    public long ID { get; set; }

    public virtual CalculationType CalculationType { get; set; }
    public virtual ApplicationUser Creator { get; set; }
}
1
12
3/26/2015 8:21:43 AM

Popular Answer

1) Is Lazy Loading enabled? If not, you need to explicitly load your navigation properties with the '.Include' syntax.

2) Are you sure EF should be able to detect that relation? Did you use Code First or Database First?

Edit: 3) Are you sure there is data in your database and that the foreign key from Indicator to IndicatorGroup has a value for that specific record? I am saying this because the value "null" is valid if there is simply no data.

P.S. If you do not see a foreign key on Indicator called "IndicatorGroupId", there might be an "IndicatorId" on the table "IndicatorGroup", in which case - going from the names you provided - your database is misconfigured and you will need to use fluent syntax or data attributes to instruct EF on how to make the foreign keys.

5
3/26/2015 7:29:41 AM


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