I have a couple of tables in my schema with PK and FK relationships. I have created the DAL using the SubSonic generator. If I create a new parent and its children, how should I save both? Separately or in one shot?
e.g.
Parent.Save();
ChildCollection.SaveAll();
I tried the above, but it does not work because ChildCollection does not have its parent's ID. Is it that I have to assign parent IDs for each child myself or is there an option to save it all in one shot?
Assumption: That your Primary Keys are auto generated by your Data Base. If so, what you will need to do first is Save() the parent and then populate the ParentID property in each of the objects in your ChildrenCollection. Once you have done that, you will be able to Save() your ChildrenCollection.
Parent.Save();
ChildCollection.ForEach(x => x.ParentID = Parent.ParentID);
ChildCollection.SaveAll();
You can use partial classes with custom overload of save function to provide the desired functionality.
public partial class Class1
{
public void Save(bool childern)
{
Save();
if (childern)
{
//based on primary/foreign key SubSonic provides
//methods to fetch child collections related to
//this (primary key) table.
ChildernCollection col = Childerns();
col.SaveAll();
}
}
}
Related
i have create an sql function in my database that take to Date params and get data from 5 tables.
after that add it to project as entity framework from database and the code generated is:
[DbFunction("Dr_EmploEntities", "SelectEmployee")]
public virtual IQueryable SelectEmployee(Nullable frm_date, Nullable to_date)
{
var frm_dateParameter = frm_date.HasValue ?
new ObjectParameter("frm_date", frm_date) :
new ObjectParameter("frm_date", typeof(DateTime));
var to_dateParameter = to_date.HasValue ?
new ObjectParameter("to_date", to_date) :
new ObjectParameter("to_date", typeof(DateTime));
return ((IObjectContextAdapter)this).ObjectContext.CreateQuery("[Dr_EmploEntities].[SelectEmployee](#frm_date, #to_date)", frm_dateParameter, to_dateParameter);
}
public DbSet SelectEmployee_Result { get; set; }
as you see i have now "SelectEmployee_Result" that don't take any params, and "SelectEmployee" that take two date params.
after that i have create an controller for "SelectEmployee_Result" class.
after that i run my project Index View that working with "SelectEmployee_Result" class give me err:
"The type 'SelectEmployee_Result' is mapped as a complex type. The Set method, DbSet objects, and DbEntityEntry objects can only be used with entity types, not complex types."
and i make breakpoint and see that "SelectEmployee_Result" has no data so i change the Index Code in controller and fill "SelectEmployee" with two date params
and when run got same err msg too.
so how can i fill "SelectEmployee_Result" from the beginning with data between two dates to let me use it in all views ?
all what i need here is view data i got i edit before saving it in database Like using DataTable but i need to do that from Entity with sql function
and what is difference between "SelectEmployee" that is my function name and that is need two params and "SelectEmployee_Result"?
I have been trying desperately to delete an item from the database but have so far been unable to get it to work. The error message I see is this one:
"The operation failed: The relationship could not be changed because one or more of the foreign-key properties is non-nullable."
I am using EF4.1, with EDMX (Database first) and POCO objects. I have a repository for each type and a general repository that implements the base methods.
The specific problem is when I want to delete an item. Deleting the children is not a problem - everything works perfectly - the problem is when I come to delete the entity itself.
Consider the following model. I have an entity "Foo" which has a 1 to many relationship with "Bar". I call the following method in my repository:
public override void Delete(Models.Foo entity)
{
//Load the child items...
base.Context.Entry(entity).Collection(x => x.Bars).Load();
//Bar
BarRepository barRep = new BarRepository();
foreach (var item in entity.Bars)
{
var obj = barRep.GetById(item.ID);
barRep.Delete(obj);
}
barRep.Save();
//First attempt
//base.Delete(entity);
//base.Save();
//Have to resort to some SQL
base.ExecuteSqlCommand(string.Format("delete from Foo where ID = {0}", entity.ID));
}
The GenericRepository "Delete" method is:
public virtual void Delete(T entity)
{
_entities.Set<T>().Remove(entity);
}
The GenericRepository "Save" method is simply:
public virtual void Save()
{
_entities.SaveChanges();
}
What I would like to get to work is this:
//First attempt
//base.Delete(entity);
//base.Save();
But unfortunately the only way (currently) for me to delete the item is to run some SQL which just calls _entities.Database.ExecuteSqlCommand(SQL).
I've read a lot of things but nothing seems to work. I would really appreciate some help in trying to understand what is going on.
Thanks,
Jose
I have a couple of tables and have defined relationships for them.
{Table Department} {Table Unit} {Table Branch}
A Department can have more than one branch, a branch can only belong to one department. I need to be able to get the department name, departmentid, branchname
Branch has an instance of departmentid in it.
How do I pull this in one ORM call?
class Model_Admin_Departments extends ORM
{
protected $_has_many = array('branches' => array ());
class Model_Admin_Branches extends ORM
{
protected $_belongs_to = array('departments ' => array());
I have also created the foreign key constraints on the db side with action cascade on delete. Could this cause problems or that is fine?
Assuming you have the right relationships declared you should be able to use the with(...) method on your ORM object.
About Domain Driven Design, Order and OrderLines are always seen as an aggregate, where Order is the root. Normally, once an order is created, one cannot change it. In my case however, that is possible. Instead each order has a state determining whether the order can be changed or not.
In this case, are both Order and OrderLines their own “aggregate root”? I need to be able to update order lines, so I figure that they should have their own repository. But I do not want to retrieve order lines, and persist them without the order. So this indicates that there’s still an aggregate where Order is the root with a factory method to create order lines (Order.CreateOrderLine(quantity, text, …).
Another approach could be to update the Order when the order lines collection has been modified, and then call UpdateOrder(Order). I would need some way of detecting that only the collection should be updated, and no the Order itself (using Entity Framework).
What do you think?
Order lines shouldn't be an aggregate of it's own, and doesn't need it's own repository. Your aggregate should be setup something like this...
public class Order
{
private List<OrderLine> _orderLines;
private OrderState _orderState;
public IEnumerable<OrderLine> OrderLines
{
get { return _orderLines.AsReadOnly();}
}
public OrderState Status
{
get { return _orderState; }
}
public void DeleteOrderLine(Guid orderLineID)
{
if (Status.IsProcessed)
throw new InvalidOperationException("You cannot delete items from a processed order");
OrderLine lineToRemove = _orderLines.Find(ol => ol.Id == orderLineID);
_orderLines.Remove(lineToRemove);
}
public void AddOrderLine(Product product, int quantity)
{
if (Status.IsProcessed)
throw new InvalidOperationException("You cannot add items to a processed order");
OrderLine line = new OrderLine(product.ProductID, (product.Price * quantity), quantity);
_orderLines.Add(line);
}
}
Entity framework has some built in features to detect changes to your object. This is explained here (conveniently with an order/order lines example): http://msdn.microsoft.com/en-us/library/dd456854.aspx
I have app that stores tree structure in CoreData.
There is an ManagedObject, "Item", and it has attributes:
itemId (string)
List item
title (string)
parentId (string)
parent (relationship to Item)
parentTitle (string)
parentId points to another Item object.
How do I make property parentTitle to be filled automatically with title of parent Item ?
While Martin's suggestion is a good solution for derived values, my question on yours is, why would you want this? You are not manipulating the value from the parent at all, ever. Since you are just accessing it, access the parent directly via KVC such as:
Item *item = ...;
NSString *title = [item valueForKeyPath:#"parent.title"];
//Do something with title
The only time you would want to use the keyPathsForValues... functionality is if you are changing something based on that value. If you are just accessing it, use KVC directly.
This is a possibility to achieve the desired functionality:
// implement in Item.m
// manages KVO notifications
+ (NSSet *)keyPathsForValuesAffectingParentTitle
{
return [NSSet setWithObjects:#"parent.title", nil];
}
// getter for parentTitle
- (NSString*) parentTitle
{
return [self valueForKeyPath:#"parent.title"];
}
additionally declare the property for parentTitle as readonly in Item.h
There is no need to declare a Core Data attribute "parentTitle".
The only problem I see with this solution is the following:
Item A is parent of item B
A gets turned into fault
B is still active and some View is bound to B.parentTitle
The view gets a notification because of the dependency declared with keyPathsForValuesAffecting, still object A is already faulted (and on shutdown unable to be unfaulted again) does Core Data manage such faulting&observation problems automatically?