We are starting a new web based product in which we are planning to expose our business logic through WCF services. We will be using ASP.NET 4.0, C#, EF 4.0. In future we want to build iphone applications and WPF applications based on the services. I have been reading a lot about using POCO vs Self Tracking Entities (STE) and from my understand the STEs do not work well with the web scenario.
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I have POCO's in a separate project and now I need Self Tracking Entities. Does anyone know if I need to generate new POCO's that are self tracking and they will replace my current POCO's? Or, do I setup self tracking entities in addition to my current POCO's?
View 1 RepliesI have a Consumer class and a BillableConsumer : Consumer class. When trying to do any operation on my "Consumers" set, I get the error message "Object mapping could not be found for Type with identity Models.BillableConsumer.
From the CSDL:
[code]....
Is this because I did not specifically add the BillableConsumer entity to the object set? How do I do that in a POCO scenario?
let us assume that I have a reusable business layer that further makes use of a data access layer that was implemented using Entity Framework 4.0. The entities returned/consumed by the business layer are self-tracking, allowing us all the goodies that come with those type of entities. I would like to be able to store the entities I work with across post backs (on order to avoid re-querying every time). Basically let us assume I have a paged GridView with 10 items in it, and something like a DetailsView to edit those items. Every time you select a new row on the grid, the details view updates with the information of the selected row. My preference would be to only query for the entities on the initial request of the page and store it in session. Then subsequently I have a list of entities that I can work with and eventually modify and send back to the business layer with all of the changes.
I really want to use session instead of view state to reduce the page payload (self tracking entities are heavy) however I really like view state for this because of the fact that when the user navigates away from the page there is no residual effect. Some of the things that worry me are: When a user navigates away from the page to another page, the entities from the previous page are still in session. I could always do something on load of a page to do housekeeping type of work. Not sure if that's good practice. I am worried about people opening browser tabs and having two views into the same page, it seems like that might pose a problem. Is this even a good approach? Seems like I am trying to have the best of all worlds, it would definitely be much easier to simply re-query on every post back for the entities and pay the 50-100ms hit of the database trip.
I have a model that consists of Order, OrderLine, Product.
I want to create an Order and add OrderLines (each OrderLine related to a Product). I create the Order and add new OrderLines to it. Between posts I store the Order entity in Session (or ViewState). Just so you know I have added suppport for binary serialisation which works fine.
The relationship is therefore Order > OrderLine(s) > Product(s).
You might have already guessed what the problem is - that when I SaveChanges() I get the usual 'AcceptChanges cannot continue because the object's key values conflict with another object in the ObjectStateManager.' error.
I have referred to a number of articles online but none seem to handle this case (where I have the relationship across more than two entities) e.g. [URL].
This must be a very common requirement surely? Is there anyone out there doing the same kind of thing with Entity Framework (and without using DTOs etc)?
I have a datamodel with a couple of tables. One of my tables have about 40 fields (I know that is a lot, but we have to keep the structure in place as we are upgrading a classic ASP project to MVC). Some of my Actions only updates 1 or 2 fields in my table.
Is there a way to create Entities, for instance, that only contains the contact details of the client table, and not any other details, and then another entity that contains only the address details. I don't want to submit the entire row when I only update telephone details, or the client's picture.
How to use Stored Procedures with Linq to Entities? I prefer an example with input and output The videos on asp.net only show how to do this with Linq to SQL.
View 5 RepliesI have a simple join:
SELECT * FROM MessageAlerts AS A LEFT OUTER JOIN Contacts AS C ON A.ContactId = C.Id LEFT OUTER JOIN
Users AS U ON A.UserId = U.Id INNER JOIN Businesses AS B ON B.Id = C.BusinessId OR B.UserId = U.Id
how to do this : ON B.Id = C.BusinessId OR B.UserId = U.Id with linq in entity framework.
WHY are all the examples on this site linq to SQL? Did ms not themselves announce dropping support for l2SQL over a year ago? i really don't get it. Examples are great.. but really not helping me since i've gone ahead and listened to MS. And can someone at MS clarify what the position is for linq 2 SQL.. Is it supported? Recommended? What the hell.
View 7 RepliesI use Linq To Entities to get 2 objects m1 & m2. And I don't understand why 2 different objects reference the SAME Template table.
I suspect that the reason due to the connection between MConfigOnPage1, MConfigOnPage2 with MConfiguration. Maybe it should be splitted somehow?
Here I attached my ERD and the code.
[Code]....
I make ASP.NET MVC3 application for spa and I've encoutered problem with M:N relationship. I've got this model Each Insurance Company has different pricing for each patient medical indication, so sample data looks like this:
IC
Indication
Patient
IC1
Indication1
Patient1
Patient2
Indication2
Patient3
[Code]....
And I don't know how to make Edit with possibility of changing not only Indication but IC to.
Having the following model Admin and AdminGroup is joined by AdminAdminGroup which has (AdminId, AdminGroupId) fields. When I add a new Admin row AdminGroups are associated with it automatically however this only works on INSERT.When I'm trying to update or associate more AdminGroup's with particualr Admin row (_repo.Update((DataLayer.Admin)row);) only Admin gets updated and no groups are ever modified.What is the correct way of updated "related" entities? so that AdminGroup also get's updated.
View 6 Repliesi am having a little problem in mapping all the entities in contained in the namespace "nhibernateTest.Domain" . it basically contains all the Map Classes like , StudentMap, DepartmentMap etc. .. now in case of normal nhibernate what we used to do is :
[Code]....
now what it used to do is . look for all the "*.hbm.xml" files in my namespace and automatically map them...
how to do the same for fluent nHibernate ? so that it looks for all map classes in folder
"nhibernateTest.Domain" ...resolve the namespace "nhibernateTest.Domain"... and automatically map them so that i dont have to create the session separately for diffrent Map classes ?
I have the following admx:
I have to add the (AccData, CntactData, PhnNumber, FnclDetail)entities to the database in one shot
What's the best practices to do the add operation for the above entities??
I have I method where I insert muliple records to a SQL Server 2008 database. The table in which the records are inserted has a primary key integer column with auto increment. The problem is that I have another column called GroupId where I want an integer representing the current insert to be set, i.e. for each time the method gets called a new group id should be generated the group id column of the records to be inserted should be set to this value. What's the best way to generate this group id? I guess I could do a SELECT MAX(GroupId) + 1 FROM Table to generate an id before I make the inserts but this won't be a good solution when it comes to concurrency.
View 13 RepliesI am trying to learn LINQ to entities, and am working out how to best structure my BLL layer. I have generated the entity model and have created a generic repository in my DAL that returns results as IList<T>. I initially created the BLL to also return
results as IList<T>:
public IList<DAL.Customer> SelectAll()
{ [code]...
Now I am working on the aspx page, and I can create an ObjectDataSource and configure it to use my BLL, but since I am returning IList, I can't sort since I am not using a DataView. I have seen some articles on the web for converting IList to DataView, but that seems like a lot of overhead for every query.My goal is to keep a clean separation between layers without making things overly complicated. I would like to know how others have done this, or maybe a link to a good tutorial that shows how to structure all three layers.
I have the following code for the SelectedIndexChanged event of a drop down list. This works fine as it is but this entity has a relationship to another entity (Genre). if i change the select statement to { m, m.Genre.MovieGenre }).ToList(); it doesnt work as contains anonomyous types.
[code].....
I typically don't play with betas, so I am just now getting used to vs 2010 pro. I grabbed it from DreamSpark yesterday, and so far I like all the changes.
I was wondering though, with some of the changes to ado.net EF, is there now a way to set a coding namespace for both the context as well as the entities, instead of just setting the custom tool namespace (this wraps both context and entities)? Typically, I like having my classes grouped into namespaces by type, and since a context isn't an entity, it shouldn't go in the entities namespace. note: I am talking about actual coding namespaces, not the conceptual namepsaces used internally by EF.
I was also wondering if having this (the x86 vs 2010 ide) beside my old one (x64 vs 20080 ide) would pose any problems? It seems to be working ok, I just wanted to make sure I hadn't missed announcements saying I had to de-install one before installing the other.
I am building a web application in asp.Net 4.0 and entity framework. I am trying to retrieve a list of products based on a collection of id's. I first gather all the id's in a collection and then pass it to the linq query. I am trying to get a functionality similar to the IN clause in SQL. The problem seems to be with the Contains() method in the Linq to entities query. Here is my Linq code:
[Code]....
I got the above Linq to entities method from here: [URL]
I use the ObjectDataSource in an ASP.NET Application.
Using the ASPxGridView. When Updating it goes back to the Data Access Layer and tries to update the Entity, now as I can see while having some properites (Columns, Visible = false) when the entity arrives in the update method the visible = false columns have no values.
I don't want to show all the columns...what if I need 3 of the 30 columns? So I thought I would get the original entity from the context and merge the differences from the updated entity.
I am currently trialing EF4 code-first. My POCO classes inherit from an Audit class that contains CreatedBy, CreatedOn, UpdatedBy, UpdatedOn. I was hoping the framework would include the Audit properties in my Action table when creating my database, however this doesn't appear to be the case. Does anyone know how to enable this without overriding the OnModelCreating() method?
Public Class Audit
Public Property CreatedOn as DateTime
End Class
Public Class Action
inherits Audit
Public Property ActionId As Int32
End Class
I am currently developing some user controls so that I can use them at several places within a project. One control is a about editing a list of addresses for a customer. Since this needs to be done at several places within the project I want to make it a simple user control. The user control contains a repeater control. By default the repeater displays one address item to be edited. If more addresses need to be added, the user can click on a button to append an additional address to be entered. The user control should work for creating new addresses as well as editing existing ones.
The address business entity looks something like this:
public class Address
{
public string Street { get; set; }
public City City { get; set; }
public Address(string street, City city)
{
Check.NotNullOrEmpty(street);
Check.NotNull(city);
Street = street;
City = city;
}
}
As you can see an address can only be instantiated if there is a street and a city.
Now my idea was that the user control exposes a collection property called Addresses.The getter of this property collects the addresses from the repeater and return it in a collection. The setter would databind the addresses to be edited to the repeater.
Like this:
public partial class AddressEditControl : System.Web.UI.UserControl
{
public IEnumerable<Address> Addresses
{
get
{
IList<Address> addresses = new List<Address>();
// collect items from repeater and create addresses
foreach (RepeaterItem item in addressRepeater.Items)
{
// collect values from repeater item
addresses.Add(new Address(street, city));
}
return addresses;
}
set
{
addressRepeater.DataSource = value;
addressRepeater.DataBind();
}
}
}
First I liked this approach since it is object oriented makes it very easy to reuse the control. But at some place in my project I wanted to use this control so a user could enter some addresses. And I wanted to pre-fill the street input field of each repeater item since I had that data so the user doesn't need to enter it all by his self.
Now the problem is that this user control only accepts addresses in a valid state (since the address object has only one constructor). So I cannot do:
IList<Addresses> addresses = new List<Address>();
addresses.Add(new Address("someStreet", null)); // i dont know the city yet (user has to find it out)
addressControl.Addresses = addresses;
So the above is not possible since I would get an error from address because the city is null.
Now my question: How would I create such a control? ;)
I was thinking about using an Address DTO instead of a real address, so it can later be mapped to an address. That way I can pass in and out an address collection which addresses don't need to be valid.
Or did I misunderstood the way user controls work?
I have a message table that self joins to itself where Message.ID == Message.Parent. So I have 1 Message with several ChildMessages. This is set up nicely with a Navigation property.
The code is currently:
var message = from m in soe.Messages.Include("ChildMessages")
where m.ID == id
&& m.IsActive
select m;
return message.FirstOrDefault();
What I really want is to only return 1 Message (that is equal to a particular ID and isActive) with all of its Active ChildMessages and I want to do it in one call to the database.
i am working on POCO entities. i had a requirement to provide Edit feature for parent and respective Child records in single View.
Eg: Parent-Customer, Child-Order tables
when updating the parent entity by using => UpdateModel(CustomerIns);
and updating the child entity by using => TryUpdateModel(CustomerIns.Order, "Orders");
The Child Controls Names are like Orders[0].OrderID,Oders[0].OrderDate,etc
The Parent and Child Entities are updating when UpdateModel() is called but when saving Changes by calling Context.SaveChanges() i am getting exception like:
"The operation failed: The relationship could not be changed because one or more of the foreign-key properties is non-nullable. When a change is made to a relationship, the related foreign-key property is set to a null value. If the foreign-key does not support null values, a new relationship must be defined, the foreign-key property must be assigned another non-null value, or the unrelated object must be deleted."
I have a table of user ids that is huge.
I have an array of user ids that I want.
I have two tables that have a foreign user id key.
What is the best way to get this information performance wise?
Ideally in SQL the final result would be somewhat like this (null values if there is no user ID in one table but not the other):
userid table1value table2value
1 null 12
5 123 null
