Entity Framework - Connect Data Access Methods To UI?
Mar 2, 2010
I am seriously at a loss here. The three things that will not change in this project are the fact that we are using the Entity Framework to do our data access, the fact that we want thorough unit testing and that our UI is asp.net. My question is how the hell do you make this work in Asp.net? E.g. You can use an ObjectDataSource to connect a method to a control, but if this control is a FormView you have all these problems [URL] to deal with and it simply doesn't work.
Furthermore, with grids, you don't get paging or sorting out of the box unless you use an EntityDataSource which basically circumvents your entire application. I can't be the only person who cries at this. What do you do?
I have a few entities I'd like to update at the same time. However I'd like to write individual update methods in each classes partial class file, for each entity and call them all at the same time. For example:
public sub UpdateEntity1() ... end sub
public sub UpdateEntity2() ... end sub
public sub UpdateEntity3() ... end sub
public sub UpdateAll() UpdateEntity1() UpdateEntity2() UpdateEntity3() end sub
My question is how do I manage the object context? do I create one object context in the class I'm calling UpdateAll(), then pass it as a parameter to each individual update method? Or do I create a new context for each Update? I'd like to use the same context because the object are related, and this would decrease the db calls to update all the records.
I have been asking my self this question from the time i started workin in the software development field, What is the best way to access data? Which gives the best performance? Which is the best for maintainability? There are lots of solutions to deal with database in the Asp.Net web app,Entity framework 4.0 Classes generator using ADO.Net such as Code Author ( i liked the way it works and the way it accesses the database using the data access block in Microsoft Enterprise Library). i will start a new project tomorrow,and i don't know which approach is better?
A relative newcomer to .net MVC2 and the entity framework, I am working on a project which requires a single web application, (C# .net 4), to connect to multiple different databases depending on the route of access, (ie subdomain).
No problem with this in principle and all the logic is written to transform the subdomain into an entity connection and pass this through to the Entity Model.
The problem comes with the fact that the different database whilst being largely similar in structure contain 3 or 4 unique tables bespoke to that instance.
To my mind there are two ways to solve this issue, neither of which i am sure will be possible.
1/ Use a separate entity model for each database. -Attempts down this route have through up conflicts where table/sp names are the same across differnt db's, or implicit conversion errors when I try and put the different models in different namespaces. or
2/ Overwrite the classes which refer to the changeable database objects based on the value of a base controller property.
My question is if either of theser routes can ever work in principle or if i should just give up on the EF and connect to the dtabases directlky using ADO. Perhaps there is another way to solve this problem i haven't thought of?
Is there a way to export a EF 4.0 Data Model to EF 3.5?
I looked around and found that we are not able to access EF 4.0 from a ASP.Net 3.5 project here: [URL]
Our project is the 1st to go to .Net 4.0 using Entity Framework and we (the team) were wondering if there was a way for the other projects that "might" need to access our data that are still using the .Net 3.5 framework.
I'm currently learning entity framework (from the Julia Lerman book "Programming Entity Framework") and got really confused at the grouping part.
var contacts = from c in context.Contacts group c by c.Title into myGroup select myGroup;
This is supposed to return a Grouping<K,T> type, but the book didn't give an example on how exactly do I access this "contacts" query and I can't figure it out. When I did foreach(var contact in contacts), my "contact' variable has no knowledge of any of the properties of the Contact type (contact.FirstName etc).
First and foremost ... I already made a few changes in the template, the most important one changing the methods generated for stored procedures with OUTPUT parameters and no resultset so that instead of instantiating a few OutputParameter objects, passing them to the method and extracting the values (all without any type checking) you just call the method with a few "out someType?" parameters so I do not need the very basics. I am totally confused by all those GlobalItem, EdmProperty,BuiltInTypeKind, TypeUsage and all this made of objects, all alike and all different though so as soon as I need more data than what's already used by the template I run into problems :-(What I would like is to change the WritePrimitiveTypeProperty() so that it outputs [StringLength(xxx)] for all char, varchar, nchar and nvarchar properties. But I can't find a way to get from an EdmProperty in the model to the database type in the store.anyone is interested here's the modified stored procedure mapping code for the template. The first code replaces the original in the .tt:
[Code]....
the second needs to be added into a copy of EF.Utility.CS.ttinclude that you add to your project and reference from the .tt
I am trying to add a new entity and have to refernce associated data to add it. I cannot load the Referencetables. Giving "The EntityReference could not be loaded because it is not attached to an ObjectContext." How do i complete this task in Entity Framework 3.5
I am new to entity framework , it is really very good , but I want to know what is the difference between using entity framework with stored procedure or without stored procedure , which one the faster and what is the benefits for using stored procedures with entity framework.
I have an EDM, it includes the entities extension and history. My goal is to use history to keep track of all the changes made to extension entity. For example, if extension with ID 223 has its property 'Name_Display' changed - I want the history entity to record this.
I'm using ASP.NET with VB.NET. Where in my code do I put the hook to say, "update the history entity" and what should that hook look like?
I get an cast exception when i am trying to insert an entity in Entity Framework (using code-first). From this code :
public virtual T Insert(T entity) { return Context.Set<T>().Add(entity); }
The cast exception is like "impossible to cast ...Collection'1(Entity) to type (Entity)" I can't figure out why. I am pretty sure ive done everything right. Post entity
public class Post { public long PostId { get; private set; } public DateTime date { get; set; } [Required] public string Subject { get; set; } public User User { get; set; } public Category Category { get; set; } [Required] public string Body { get; set; } public virtual ICollection<Tag> Tags { get; private set; } public Post() { Category = new Category(); if (Tags == null) Tags = new Collection<Tag>(); }................................
I am mapping a stored procedure to an entity by right clicking on the entity (in the .edmx) and selecting "Stored Procedure Mapping." This brings you to a Mapping Details - "Name of Entity" Window that allows you to select the insert, update, and delete stored procedures associated with the Entity. It also maps the stored procedure parameter to the Entity "Property" (Column).
I'm gettin an error "error 2042: Parameter Mapping specified is not valid." The cause of the error is fairly obvious, in the Insert stored procedure that has been selected, a 'CHAR' parameter is being mapped to an Int32 Entity Property. I altered the stored procedure parameter to match the entity, I deleted the stored procedure, readded, and reslected it as the Insert function. I also cleaned, validated, updated model from database. No matter what I do, the parameter list in the mapping details doesn't reflect the change to the stored procedure. It's stuck on a char --> int32 mapping, even though it has been changed, like it's buried deep in meta data some where.
I have a stupid problem with the Entity Framework. I get the following Exception:
[Code]....
I have an entity with a 4 fields representing the primary key. I copy it via serialization (works fine). I set the old entity to not valid (Datefield set to a date in the past, this field is part of the PK) and set the copied entity to DateTime.Now.Date. When I call context.AddObject I get the Exception above. I tried copying the entity via reflection but the entity has 3-4 references. And when copied, I get another Exception before even Adding the entity to the context. I also tried setting newObj.EntityKey = null and reset all the fields neccessary for the PK. I just want a whole copy of an entity with a different primary key (and some other fields changed too) and Create it in the database.
I'm writing a custom .NET MembershipProvider (not the built in one) and trying to update using Entity Framework. But of course i have no access to (Try)UpdateModel. How can i update it?
I have an Events table and an InstallmentPlans table. The relationship is 0..1 : an Event can have 0 or 1 Installment plans. If I want to remove the existing InstallmentPlan for an event, how do I do this? Setting it to null doesn't seem to work:
Here's a simple code snippet where I create a new Entity object and call SaveChanges() to create a new record in the mapped database table.
[Code]....
What I'm trying to figure out is whether there is a way to derive this new key for my entity, e, from the ObjectContext, m? The reason for this is that the way my actual code is structured, my entity object is already out of scope at the point where I call the SaveChanges() method.
But ofcourse it is not working as I want to. The Ordering works on Question.Order, but I would also the Questions.SubQuestions List to be ordered according to SubQuestions.Order
How can I give set foreign key value field in Entity Framework. I have Kartlar entity (related from kartlar table). I need simple save method this field but, RehberID, KAmpanyaId,BirimID is foregin Key....
public static class SatisServicesUpdateTables { public static void SaveKartlar(int RehberID, int KampanyaID, int BrimID) { using (GenSatisModuleEntities genSatisKampanyaCtx = new GenSatisModuleEntities()) { Kartlar kartlar = new Kartlar(); kartlar.RehberReference.EntityKey = new System.Data.EntityKey("genSatisKampanyaCtx.Rehber", "ID", RehberID); kartlar.KampanyaReference.EntityKey = new System.Data.EntityKey("genSatisKampanyaCtx.Kampanya", "ID", KampanyaID); kartlar.BirimReference.EntityKey = new System.Data.EntityKey("genSatisKampanyaCtx.Birim", "ID", BrimID); kartlar.Notlar = "hfhfhfhfhfhfghfghfgfghk"; genSatisKampanyaCtx.AddToKartlar(kartlar); genSatisKampanyaCtx.SaveChanges(); } } }
But it throws to me : ArgumentException was unhandled by user code link text
I have a weired problem. One of the pages in my application show's status of tasks in a table. I am using entity framework ( entity to object) to do all the data handling with DB. I noticed that even though the status is updated in DB, its not reflected on my webpage even after continuous refresh! If i stop the server and start the application again (currently running on VS2008 dev server) the updated data is displayed!
Am I seeing the cached data? how do I prevent this from happening?
I have just added the Dynamic Data Filtering library to an Entity Framework based Dynamic Data web application, but on trying to access List.aspx, I get the following error. Is there anything I can do about this on .NET 4?The method 'Skip' is only supported for sorted input in LINQ to Entities. The method 'OrderBy' must be called before the method 'Skip'.
I have a web form in asp.net. I load the data on the page using EF4 and a foreach. Now it is time to save that data. What is the best way to do that using a postback?
I've written a 2-tier C# asp.net application. Everything works OK, but if I modify the SQL Server data using the management console, the changes are not displayed on screen. It seems the application reads the data from a cached instance.
I have tried everything to make sure it's not a browser cache issue... the data remains static until I restart the app or restar the web site. even clearing IIS cache doesn't help. If the data is updated by the application, it works ok... Any info about a default setting on the EF that caches data automatically?I'm running Win Server 2k8 and SQL Server 2008, but the problem was there also for SQL2005.
Picture Properties id name Navigation Properties Firm
Firm Properties id name email Navigation Properties Picture
So column id_firm from table Picture is column Firm in model Picture ? What type should have column Firm in model Picture - int, Firm or something else ?
