i'm trying to do a simple linq 2 sql many-to-many, insert some data, operation.
here's the stock Northwind model representing a many to many:
alt text http://www.iaingalloway.com/images/linq-detail.jpg
Now what i'm trying to do is insert a new order and if the product doesn't exist, then insert that at the same time, within the same transaction. The error i'm getting is:
System.Data.Linq.DuplicateKeyException: Cannot add an entity with a
key that is already in use.
So this is my (pseduo) code:
using (SqlContext db = new SqlContext())
{
// Get existing or create a new instance.
Order newOrder = GetOrder(order.Id) ?? new Order();
// Left to right stuff.
newOrder.Foo = order.Foo;
// Now associate this new order to a product (which might not exist).
if (!order.ProductList.IsNullOrEmpty())
{
// We have some products...
IList<Order_Detail> orderDetailList = new List<Order_Detail>();
foreach(Models.Product product in order.ProductList)
{
// Associate each product to the a new order_detail.
orderDetailList.Add(new Order_Detail
{
Product = new SqlContext.Product
{
Foo = product.Foo
}
});
}
// Now associate all the order_details to this order.
newOrder.Order_Details.AddRange(orderDetailList);
if (newOrder.Id <= 0)
db.InsertOnSubmit(newOrder);
db.SubmitChanges(); // <-- exception throw here.
}
}
I'm assuming i need to save the products first before i try and save the order? I'm so confused :(
// Associate each product to the a new order_detail.
orderDetailList.Add(new Order_Detail
{
Product = new SqlContext.Product
{
Foo = product.Foo
}
});
One thing that is wrong here, is that you create a new product to set on your Order_Detail.Product property. Instead , you should take the product that's comming from the database and set it on the property.
I'm not sure what order.ProductList has inside - if these products are loaded from the database then you should set them directly to your Order_Detail.Product instead of doing new SqlContext.Product.
#jfar L2S does support many-to-many relationships , you just can't have a property Products on your Order ( in this case this is actually a good thing because OrderDetails has Quantity and other properties).
Many to Many relationships aren't supported in Linq2Sql. :(
There are a couple of workarounds:
http://www.iaingalloway.com/many-to-many-relationships-in-linq-to-sql
http://blogs.msdn.com/mitsu/archive/2008/03/19/how-to-implement-a-many-to-many-relationship-using-linq-to-sql-part-ii-add-remove-support.aspx
Weird that the picture of your db schema is the same as one of the articles...
Related
is there a way to make a laravel trigger for this sql command? sorry I am new to laravel and having a hard time figuring it out.
So what should happen is when the table.a get its content, it will automactically fill the column with ids from the other table. is it possible for laravel? Thank you so much.
UPDATE table_a
INNER JOIN table.b ON table_a.account_code =
table.ac_code
SET table_a.ut_id = table.ut_id, table_a.pj_id
= table.pj_id
I used to use laravel event for trigger stuff in laravel (it assumes you have models on this). In your to be listened Model_B (table_b), you can define something like :
public function boot()
{
parent::boot();
static::created(function ($model) {
/*update table a here*/
$ut_id = $model->ut_id;
$pj_id = $model->pj_id;
Table_A::customUpdate($ut_id, $pj_id);
});
}
Please define your public customUpdate( ) as you want.
Check laravel doc above to see other possibilities for boot methods: creating, created, updating, updated, saving, saved, deleting, deleted, restoring, restored
I have the database just like this
==== Invoices ====
id
costumer_id
description
==== Costumers ===
id
firstname
lastname
Now I have made the relation in between models just like this.In Invoices models the relation is as like this
public function relations()
{
return array(
'customer' => array(self::BELONGS_TO, 'Customer', 'customer_id')
);
}
In costumer model the relation is just like this
public function relations()
{
return array(
'invoice' => array(self::HAS_MANY, 'Invoices','customer_id')
);
}
Now as my relation is defined one costumer has many invoices and the invoice is belongs to the costumer.
Now I made multimodel and loaded the Costumer model into Invoice model just like this.
public function actionCreate()
{
$model = new Invoices;
$customers = new Customers;
// Uncomment the following line if AJAX validation is needed
// $this->performAjaxValidation($model);
if (isset($_POST['Invoices'],$_POST['Customers']))
{
$model->attributes = $_POST['Invoices'];
$customers->attributes = $_POST['Customers'];
$valid = $model->validate();
$valid = $customers->validate();
if($valid)
{
$model->save(false);
$customers->id = $model->customer_id;
$customers->save(false);
$this->redirect(array('view','id'=>$model->id));
}
}
$this->render('create',array(
'model'=>$model,
'customers'=>$customers,
));
}
Here every thing is okay. I can insert the data for both models easily. But my problem comes here in the way that when I am inserting data from Invoice multimodel the foreign key id is not changing. It is showing zero everytime. Can some one tell me where I am wrong.Any help and suggestions will be highly appriciable.
My guess is that you are overriding the customer's primary key with the invoice's foreign key. I do not say that's not correct that way (maybe in your scenario it makes sense).
Let me explain what you are doing in that code:
First, you create new instances of two models, Invoices and Customers. Yii understands that as "they wish to insert new items in the database".
Then, you check if there are the items coming from an ajax form. If true, then,
You populate Invoices (defined as $model. I'd change it to $invoice, in case you need to edit and understand it further).
You also popupulate the customer's information, overriding the $valid value (so, you don't know if invoice is actually valid).
If valid (remember you're only validating customer's information), do,
Save the invoice
Override customer's id with invoice's foreing key to customer.
Save the customer, and redirect.
Now, what I got from that:
$valid doesn't work as expected: I'd change that to an incremental assignment.
You may not be passing a customer_id coming from the ajax form. Foreing keys are integers, and so if not defined within a model, it becomes 0 or NULL.
You are always passing id = 0 / NULL to Customer's model, so it would probably warn you when validating. However, you are using save(false), which means it doesn't pre-validate on save, so you never know it doesn't work.
So, according to this:
public function actionCreate()
{
$invoice = new Invoices;
$customers = new Customers;
// Uncomment the following line if AJAX validation is needed
// $this->performAjaxValidation($invoice);
if (isset($_POST['Invoices'],$_POST['Customers']))
{
$invoice->attributes = $_POST['Invoices'];
$customers->attributes = $_POST['Customers'];
$valid = true; /* expect it is always valid */
$valid &= $invoice->validate(); /* if $invoice is not valid, $valid will be false (true&false = false) */
$valid &= $customers->validate(); /* same as the above line */
if($valid)
{
$customers->save(); /* First save customers. It's the Foreign item */
$invoice->customer_id = $customers->getPrimaryKey(); /* new instances use getPrimaryKey() to get its id */
$invoice->save(); /* Save invoice AFTER getting customer's primary key */
$this->redirect(array('view','id'=>$invoice->id));
}
}
$this->render('create',array(
'invoice'=>$invoice,
'customers'=>$customers,
));
}
I hope this solves your problem.
Please you need to understand a clear scenerio here. why would you use
if($valid)
{
$model->save(false);
$customers->id = $model->customer_id;
$customers->save(false);
$this->redirect(array('view','id'=>$model->id));
}
$model->save(false); tells model that if this record is not save(), the it shoud set the $customers->id = $model->customer_id;
This will only return false because. I do rather prefer if you call ( $customers->id = $model->customer_id;) before the $model->save();
REMEMBER, if you need to check if Save() returns true, then set it to $model->save(true)
I have this going me crazy,
I'm attaching a List with 1 Customer and 1 Address child record row.
Everything seems OK while debugging. 1 customer Row and 1 Address Row should inserted.
But instead I get 2 Customer Records and 1 Address Row.
I don't know why. When Attaching and looping inside the List only 1 record seen.
Any points?
[EDITED]
Code Attached:
public bool InsertUpdateCustomers(List<Customer> customerList, List<Customer> originalCustomers)
{
using (DbContext db = new DbContext(DbContext.ConnectionString))
{
db.Log = Console.Out;
List<Customer> customerCloned = new List<Customer>();
customerList.ForEach(p => customerCloned.Add(p.CloneObjectGraph()));
customerCloned.ForEach(p => p.Address =
customerList.Where(pe => pe.Id == p.Id).Single().Address.CloneObjectGraph());
customerCloned.ForEach(p =>
{
if (p.Id > 0)
{
db.Customer.Attach(p,
originalCustomers.Single(
x => x.Id == p.Id));
db.Address.Attach(p.Address,
originalCustomers.Single(
x => p.AddressId== x.AddressId).
Address);
}
});
customerCloned.ForEach(p =>
{
if (p.Id == 0)
db.Customer.InsertOnSubmit(p);
});
try
{
db.SubmitChanges(ConflictMode.ContinueOnConflict);
return true;
}
catch (Exception ex)
{
return false;
}
}
}
I have checked the Log in the output and I see indeed 2 Inserts in the table.
I don't see nothing about the Address, but inserts correctly.
It could be the foreign key problem i don't get it.
I guess you've solved this for now but I ran into a similar issue and wanted to report back my understanding of this issue for future users.
The issue, I believe, is that you are using an existing list of Customer objects retrieved from the DB using a particular DataContext. You are then creating a new DataContext in your method and with this new DataContext, you are attaching an Address object.
This Address object (assuming has a foreign key relation with Customer) creates a new Customer object in the DB since the DataContext for which SubmitChanges is called, the originalCustomer is also treated as a new record.
In other words, to avoid these problems, you must re-use the existing DataContext using which the originalCustomer List was fetched so that inserting the child record of Address doesn't trigger an entry into the parent table.
Hope this helps.
I have 2 objects - Order and Product. On the Order only productID is saved and when I view orders I want to see the product name. According to ScuttGu blog this is easily done by using a template field with Eval("Product.ProductName"). However, when reviewing the actual queries I see that for each order a separate query is made.
It doesn't sould right to me because for many rows and/or foreign keys many additional queries will be made. Doesn't it make the whole this too inefficient (i.e. why linq doesn't use a join)?
Thanks
That is because your products are lazy loaded - that is they are loaded when needed.
You can DataLoadOptions to set your fetchingstrategy, and load the products with your order:
MyDataContext db = new MyDataContext();
DataLoadOptions options = new DataLoadOptions();
options.LoadWith<Order>(order => order.Product);
db.LoadOptions = options;
var orders = from c in db.Orders
If you don't like the pr. datacontext specification of loadoptions you do something like this (not testet):
MyDataContext db = new MyDataContext();
db.Orders
.Select(o => new { Order = o, Products = o.Products})
.ToList()
.Select(x => x.Order)
.ToList();
I have implemented something like this guys fethingstrategies, which works out nicely with my repositories and the specification pattern.
This happens because at the point that Eval has run, the query already has, without said join.
When you're fetching the query you can use DataLoadOptions to include this using the .LoadWith() method:
var dlo = new DataLoadOptions();
dlo.LoadWith<Order>(o => o.Product);
var dc = new DataContext();
dc.LoadOptions = dlo;
var orders = from dc.Orders select o;
I'm trying to figure out the best way to save a simple one-to-many relationship in Linq2Sql.
Lets assume we have the following POCO model (pseduo code btw):
Person has zero to many Vechicles.
class Person
{
IList<Vehicle> Vehicle;
}
class Vehicle
{
string Name;
string Colour;
}
Now, when i save a Person, i pass that poco object to the repository code (which happens to be L2S). I can save the person object fine. I usually do this.
using (Db db = new Db())
{
var newPerson = db.People.SingleOrDefault(p => p.Id == person.Id) ?? new SqlContext.Person();
// Left to right stuff.
newPerson.Name = person.Name;
newPerson.Age = person.Age;
if (newPerson.Id <= 0)
db.People.InsertOnSubmit(newPerson);
db.SubmitChanges();
}
i'm not sure where and how i should handle the list of vehicles the person might have? any suggestions?
using (Db db = new Db())
{
var newPerson = db.People.SingleOrDefault(p => p.Id == person.Id) ?? new SqlContext.Person();
// Left to right stuff.
newPerson.Name = person.Name;
newPerson.Age = person.Age;
// add vehicles.
Vehicle firstV = new Vehicle();
firstV.Name = "some name";
firstV.Person = newPerson; // need to do this to set the person Id on the vehicle.
newPerson.Vehicle.Add(firstV);
// now when you save the Person it should save the Vehicle list
// if you set Cascade save update on the list. (not sure how to do that in L2S
if (newPerson.Id <= 0)
db.People.InsertOnSubmit(newPerson);
db.SubmitChanges();
}
Now you may choose to construct the list of vehicles at another level , with the data that's coming from the interface.
But you need to remember that it's not enough to add the Vehicle to the list on the Person object , you also need to set the vehicles Person property to the person that has the vehicles.
Observation I'm not sure about this but when you do db.People.SingleOrDefault you might be loading the whole People table in memory . That's not something you want to do. Corrected by Slace in the comments.
All you need to do is ensure that there are the appropriate relationships set up within the database.
If your Vehicle table has a PersonId and there is a foreign key between them when you add them to the DBML Linq to SQL will detect that there is a relationship between them and create a Table<T> representation of the relationship.