System.NullReferenceException: 'Object reference not set to an instance of an object.' about laraue.efcoretriggers

[win7user10]

Hi, @mehmet-erdogdu, looks like the entity doesn't contain information about table name, could you please provide your Users and Transactions models code to reproduce the issue?

[rekosko]

I'm having the same issue. What do you mean that entity doesn't contain information about table name? All I can think about is to specify e.g.: builder.ToTable("TableName"); Is there something else that you have in mind?

[win7user10]

I had this error when building a trigger for an entity that DbSet hasn't been added to DbContext. The readable exception was added for this case.

[portno]

Hi,

the issue seems to appear when using inheritance. Consider this example:

public abstract class BaseModel
{
    public Guid Id { get; set; }
}
public class Product: BaseModel
{
    // ...
}

and in DbContext:

public DbSet<Product> Products { get; set; }

and somewhere in your trigger use ... , product) => product.Id === ...).
GetColumnName(MemberInfo memberInfo) gets the MemberInfo of that expression which has BaseModel as DeclaringType and not Product which is the type that is used as a table.

Adding .Entity<BaseModel>().ToTable("Whatever") can cause other issues if you did not intend ModelBase to be a table.

[Meberem]

@portno I encountered this today with a slightly more complex setup. In my case, the base model had not been configured before the Trigger configuration runs on the builder. A simple hack that worked for me was changing the order of my IEntityTypeConfiguration<TType> from:

public class MyTypeConfiguration : IEntityTypeConfiguration<BaseModel>, IEntityTypeConfiguration<Product>
{
    public void Configure(EntityTypeBuilder<BaseModel> builder)
	{
         builder.AfterInsert(....);
    }

    public void Configure(EntityTypeBuilder<Product> builder)
	{
    }
}

public class MyTypeConfiguration : IEntityTypeConfiguration<Product>, IEntityTypeConfiguration<BaseModel>
{
    public void Configure(EntityTypeBuilder<BaseModel> builder)
	{
         builder.AfterInsert(....);
    }

    public void Configure(EntityTypeBuilder<Product> builder)
	{
    }
}

I don't know if that will work for you, or what the root cause is just yet, but it might help