Why does the EF navigation property return null?

Question

I have two models 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<alculation> Calculations { get; set; }
}

I execute this code

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

first line returns null for the CalculationTypes navigation property

The second line returns an empty collection. Why?

UPDATE snapshot database project link https://github.com/wkololo4ever/Stankin

calculation added

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

    public virtual CalculationType CalculationType { get; set; }
    public virtual ApplicationUser Creator { get; set; }
}

Answer 1

1) Is lazy loading enabled? If not, you need to explicitly load your navigation properties using the ".Include" syntax.

2) , EF ? Code First Database?

: 3) , Indicator to IndicatorGroup ? , "null" , .

P.S. "IndicatorGroupId", "IndicatorGroup" "IndicatorId", - , , - , EF , .

Answer 2

:

DbContext.Configuration.ProxyCreationEnabled = true;    
DbContext.Configuration.LazyLoadingEnabled = true;  

DbContext.Configuration.ProxyCreationEnabled false, DbContext - , Include. DbContext.Configuration.LazyLoadingEnabled true false .

DbContext.Configuration.ProxyCreationEnabled true, , DbContext.Configuration.LazyLoadingEnabled .

, :

: 3) , , Indicator to IndicatorGroup ? , "null" , .

P.S. "IndicatorGroupId", "IndicatorId" "IndicatorGroup", - , - , EF , .

, .

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; }
    [ForeignKey("IndicatorID")]
    public string IndicatorId { get; set; } //this is the foreign key, i saw in your database is: Indicator_ID, avoid this, rename it to IndicatorID or IndicatorId

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

Answer 3

, , :

, myContext.Configuration.AutoDetectChangesEnabled

, , .

Answer 4

: . , null .

, . "include" IQuearable .

: , , "" IQueryable.