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How can i configure model builder to delete all recipes when user is deleted but when recipe is deleted keep the user [duplicate]

This question already has an answer here:
Cascade deleting with EF Core
(1 answer)
Closed 2 years ago.
This is my model builder right now, but when i delete user it sets recipes userid to null.
protected override void OnModelCreating(ModelBuilder modelBuilder)
{
base.OnModelCreating(modelBuilder);
modelBuilder.Entity<ApplicationUser>().HasMany(e => e.Recipes).WithOne(e => e.ApplicationUser)
.OnDelete(DeleteBehavior.Cascade);
modelBuilder.Entity<Recipe>().HasOne(e => e.ApplicationUser).WithMany(e=>e.Recipes)
}

I think you've overstated the mapping, you only need to map one entity to the other.
Try to use this one first;
modelBuilder.Entity<ApplicationUser>().HasMany(e => e.Recipes).OnDelete(DeleteBehavior.Cascade);
modelBuilder.Entity<Recipe>().HasOne(e => e.ApplicationUser);
If the above doesn't work, try this one alone;
modelBuilder.Entity<ApplicationUser>().HasMany(e => e.Recipes).OnDelete(DeleteBehavior.Cascade);

EF Core - 2 Entities, each with a reference to another lookup Entity. On Add - IOE - cannot be tracked because another instance with the key value

We're using EF Core 3.1
We have 2 Entities - item and batch. Each have a reference to currency. When we add both an item and a batch, each with a reference to a loaded (and tracked) currency EF Core spits out the following System.InvalidOperationException:
The instance of entity type 'Currency' cannot be tracked because another instance with the key value '{Id: 103}' is already being tracked. When attaching existing entities, ensure that only one entity instance with a given key value is attached.
We're not doing anything too irregular:
var currency = _context.Set<Currency>.SingleOrDefault(currencyId);
var item = new Item(currency);
var batch = Batch.Create(currency, new[] { item });
_context.Set<Batch>.Add(batch);
item.Batch = batch;
_context.Set<Item>.Add(instruction);
And our maps have fks etc ItemMap:
modelBuilder
.HasOne(i => i.Currency)
.WithMany()
.IsRequired();
modelBuilder
.HasOne(i => i.Batch)
.WithMany();
and BatchMap:
modelBuilder
.HasOne(i => i.Currency)
.WithMany()
.IsRequired();
and CurrencyMap:
modelBuilder
.ToTable("Currency")
.HasKey(cur => cur.Id);
modelBuilder
.HasData(new Currency(103));
I wonder if anyone can point out my stupidity or at least explain where I may be going wrong?

NHibernate ClassMapping creates automatic a unique key

I use NHibernate with ClassMapping. I created an index on one of the properties, like this:
public class ShopMapping : ClassMapping<Shop>
{
public ShopMapping()
{
Table("Shops");
Id(p => p.Id, m => m.Generator(NHibernate.Mapping.ByCode.Generators.GuidComb));
Property(p => p.CountryCode, m =>
{
m.Length(10);
m.NotNullable(true);
m.Index("ShopCountryCodeIdx");
m.Unique(false);
});
}
}
This generates the index called ShopCountryCodeIdx, but I got also a unique index, called 'CountryCode' on the same column. I tried it with an without m.Unique(false), but no effects.
I just moved to a new pc. Old pc: VS2012 on 32bitand new pc: VS2015 on 64bit. NHiberate version is on both the same (3.4.1.4). Database is MySQL 5.7 (on old machine I used MySQL 5.5).
How is this possible?

Part of the problem found. I had in one of my other ClassMapping classes an unique index across three columns. One of the was also a CountryCode column. That results in this strange behavior.
Property(p => p.CountryCode, m =>
{
m.Length(10);
m.NotNullable(true);
m.Index("PanelShopCountryCodeIdx");
//m.UniqueKey("UK_psPanelShopnrIdx");
});
Property(p => p.ShopNr, m =>
{
m.Length(25);
m.NotNullable(true);
//m.UniqueKey("UK_psPanelShopnrIdx");
});
Property(p => p.PanelCode, m =>
{
m.Length(25);
m.NotNullable(true);
// m.UniqueKey("UK_psPanelShopnrIdx");
});
Getting rid of those m.UniqueKey statements, solved the problem (which let me with another challenge, how to create in this scenario a unique index across three columns from which one column has also an own (non unique) index...

NHibernate map by code keycolumn?

just started on a project to convert a NHibernate Fluent mapping into the NHibernate Mapping By Code as part of an upgrade associated with one of my old applications.
Almost there, but I stumbled upon something I can't convert properly and found myself stumped. Now I hope maybe some of you experienced out there can help me with it.
Below is the original mapping using Fluent:
HasMany<ExampleEntity>(x => x.OtherExampleEntities)
.OptimisticLock.False()
.AsSet()
.KeyColumn("ParentExampleEntityId")
.Inverse()
.Cascade.SaveUpdate();
Now I got stuck on converting the KeyColumn-part of my mapping, below is my current progress (thus keyColumn still being there):
Set(x => x.OtherExampleEntities, x => {
x.OptimisticLock(false);
x.KeyColumn("ParentExampleEntityId");
x.Inverse(true);
x.Cascade(Cascade.Persist);
}, map => map.OneToMany(r => r.Class(typeof(ExampleEntity))));
There's not a lot of documentation regarding the mapping by code part of NHibernate but I've been spending a lot of time with the posts made by notherdev (#blogspot.se). All help is appreciated.

There is a comprehensive post about <set> mapping
Mapping-by-Code - Set and Bag by Adam Bar
Small snippet, but please observe the post:
Set(x => x.Users, c =>
{
c.Fetch(CollectionFetchMode.Join); // or CollectionFetchMode.Select,
// CollectionFetchMode.Subselect
c.BatchSize(100);
c.Lazy(CollectionLazy.Lazy); // or CollectionLazy.NoLazy, CollectionLazy.Extra
c.Table("tableName");
c.Schema("schemaName");
c.Catalog("catalogName");
c.Cascade(Cascade.All);
c.Inverse(true);
c.Where("SQL command");
c.Filter("filterName", f => f.Condition("condition"));
c.OrderBy(x => x.Name); // or SQL expression
c.Access(Accessor.Field);
c.Sort<CustomComparer>();
c.Type<CustomType>();
c.Persister<CustomPersister>();
c.OptimisticLock(true);
c.Mutable(true);
<key column="" ...> mapping:
c.Key(k =>
{
k.Column("columnName");
// or...
k.Column(x =>
{
x.Name("columnName");
// etc.
});
k.ForeignKey("collection_fk");
k.NotNullable(true);
k.OnDelete(OnDeleteAction.NoAction); // or OnDeleteAction.Cascade
k.PropertyRef(x => x.Name);
k.Unique(true);
k.Update(true);
});
....

Foreign Key to a table with 2 columns primary key (CompositeId)

I've defined the primary key as following:
CompositeId()
.KeyProperty(x => x.Id)
.KeyProperty(x => x.Type);
I've tried the following:
References(x => x.EntityWith2ColsPK);
And failed with:
Foreign key (Fk_MyEntity_EntityWith2ColsPK:MyEntities [Fk_EntityWith2ColsPK])) must have same number of columns as the referenced primary key (EntityWith2ColsPKs [Id, Type])
How can I reference EntityWith2ColsPK from another entity?
Update:
I've tried the following (according to AlfeG's comment):
HasMany<EntityWith2ColsPK>(x => x.EntityWith2ColsPK).KeyColumns.Add("Id", "Type").Cascade.All();
Which failed with:
Custom type does not implement UserCollectionType: EntityWith2ColsPK
But anyway I don't want a 1 to many relation, I want a 1 to 1 relation. Still, I can't make either of them work.
Also, I've tried:
HasOne<EntityWith2ColsPK>(x => x.EntityWith2ColsPK).PropertyRef(x => x.Id).PropertyRef(x => x.Type);
Which fails with:
NHibernate.MappingException : property not found: Type on entity EntityWith2ColsPK
What can I do for this to really work?
I managed to achieve something in the db.. but yet, for some reason I suspect it maps the property "Type" twice, because I want it to be both part of the Primary Key, and part of the Foreign Key..
This is what I did:
References(x => x.EntityWith2ColsPK).Columns("EntityWith2ColsPKId", "Type").Formula("Id = :EntityWith2ColsPKId AND Type = :Type");
But I received the following exception:
System.IndexOutOfRangeException : Invalid index 8 for this SqlParameterCollection with Count=8.
Because the mapping of this entity is same as EntityWith2ColsPK:
CompositeId()
.KeyProperty(x => x.Id)
.KeyProperty(x => ((ILocalizedEntity) x).Language);
HELP!

You can use something like this since you aren't using cascade anyway on your Reference
References(x => x.EntityWith2ColsPK)
.Columns(new string[] { "ID", "TYPE" })
.Not.Update()
.Not.Insert();