MVC :: Pattern For EF 4.0 CRUD / Transactions When Updating Multiple Objects?
Nov 17, 2010
I am looking for an accepted pattern for using MVC 2 and EF. Especially I am interested on how to implement updates. Where should the ObjectContext be created, where should the queries be, how to pass a model object from the controller and have it persisted with minimum robust code. I also want to be able to use transactions when updating multiple objects.
I used Linq in an asp.net application (code behind model). With EF I was hearing it was much more n-tier friendly, but I don't find it any different, rather than people talking about POCO which to me, all it means is satisfying the desire of those that want to have control of every piece of code being created.
I have a view that is based on a view model. This model has a single property called Entity, of type ServiceProvider, which is a Linq2SQL object. This object has relationships to 2 other objects Address and ServiceProviderGroup. In a HTML view I have textboxes that allow the properties of the Entity property to be changed and also the properties of the Address object related to it.
E.g: ViewModel.Entity.Code, ViewModel.Entity.Name, ViewModel.Entity.Address.City, etc, etc.
There is also a selectlist that will allow the Entity.GroupId (int) property to be changed. This defines a relationship to the ServiceProviderGroup class which is also accessible via a Group propery. (standard linq2sql back references)
The Edit[Post] method accepts an instance of this view model and all properties (on the Entity, Entity.Address properties) are set as expected. I then lookup the original object in the database and I also bring back the original address and group data.
E.G: entity => entity.Code == viewModel.Code && entity.Address.Id == viewModel.Address.Id && entity.Group.Id == viewModel.Entity.GroupId (I'm not looking at the code, but it's something similar to this)
Either way the original Entity, Entity.Address, etc, come back from the database. I then apply the changes from the view model to the original object using UpdateModel and everything is updated as expected. But, if I try to change Entity.GroupId, i.e. change the relationship on the entity to another ServiceGroupProvider object, I get an exception in the generated code of the ServiceProvider object.
This happens in the GroupId property of the ServiceProvider class (viewModel.Entity). When it reaches the line if(!this.HasLoadedOrAssignedValue) it enters the "if" statement and throws an exception. When the data is first read from the database it skips this part. But, when UpdateModel attempts to apply the new Entity.GroupId value it throws the exception.
the best practice for a designing a simple CRUD application with some screens updating various tables (like admin pages to maintain static data for an application). the simplest way would be to drag a data grid/gridview, bind it to a dataset and use a data adapter for CRUD operations. but if this application needs to be scalable, lets say to add any extra UI/business logic in future, then is there any design pattern that can with this? should I be using an object data source control and bind it to business objects instead? or are there any better ways of doing it? should I build a complete layered application or will that be overengineering for this requirement?
Are there any transactions around multiple webservice calls.Let me start with a commonly used example -- the travel agency. A customer intends to create a travel plan through an online travel agency. To do this, the online travel application calls the following three Web services:
These three services are available from three separate vendors. If any one of these three services fails, the customer does not wish to proceed with the transaction (again, either all three services must succeed or none at all).My language programming is Asp.net c#.
One is adding Userdetails(Fn Name : AddUserDtls) and another one adding address details(Fn name : AddAddresDtls) based on UserName which will get added after execution of first method ie AddUserDtls.
Problem I am facing is :
I have a single transaction and in that I have all the methods.
After the execution of first method,with out commiting i will go to second method.
and if any error occurs in second method.
I will rollback everything including the changes made by first method also.
Here one issue is there.
Since I am not committing the changes made by first method,
While I am executing the second method I am getting error that 'No user Name exists'
I understood that if we commit the transaction before the second method starts ,it will solve the issue.
But then it creates another problem.If some problem araise in the second method,then I cannot rollback the changes made by first method since it aleready commited.
I am trying to delete three related objects on one submit. Delete fails on one of the child objects, because of foreign key contraint with another table, It deletes one (the parent) but not the two child objects. All in one SubmitChanges(). I even used the TransactionScope, still same thing. So here is the scenario:
I have an object called Page which has a collection of objects called Webinars. There is another object Called Product which is one to one with Webinar.
In my project's earlier version I used Stored Procedures (SPs) & directly used them inside presentation layer. SP contains multiple Insert & Update queries for multiple tables.
Now I have decided to use a DAL(Typed DataSets & TableAdapters)
How can i use the same SPs with TableAdapters or If not possible how to wrap Multiple TableAdapters inside Transactions.
1 more thing in my earlier version i was using Transaction in SPs & Presentation Layer.
I set a session object at one juncture in my code:
Session("my_name") = "Dave"
Later in my code I give the user a chance to update this object:
Session("my_name") = TextBox1.Text
I reload my page and display a little hello statement like this:
Label1.Text = "Hello" & CStr(Session("my_name"))
The result is: "Hello Dave" no matter what I change Session("my_name") too.
EDIT: Here is the a full code-behind I wrote up to demonstrated:
Public Class WebForm1 Inherits System.Web.UI.Page Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load Response.Cache.SetCacheability(HttpCacheability.NoCache) Response.ExpiresAbsolute = DateTime.Now.AddMonths(-1) If Page.IsPostBack = False Then Session("my_name") = "Dave" End If Label1.Text = CStr(Session("my_name")) End Sub Protected Sub Button1_Click(ByVal sender As Object, ByVal e As EventArgs) Handles Button1.Click Session("my_name") = TextBox1.Text End Sub
I found some code on the web and it threw me off. Look at the code below. You will notice only when the Hits == 1, does the cache get added. After that, the cache object isn't updated. It begs the question, does the object when updated, update the cache as well automatically? The answer here would make me remove some code in some of my classes.
I have a question, much liket this unanswered one. I'm trying to work with the entity framework, and having a tough time getting my foreign tables to update. I have something basically like this in the DB:
Incident (table):
-ID -other fields
Responses (table):
-FK:Incident.ID -other fields
And and entities that match:
Incident (entity) -ID -Other fields -Responses (EntityCollection of Responses via navigation property)
Each Incident can have 0 or more responses.
In my Webpage, I have a form to allow the user to enter all the details of an Incident, including a list of responses. I can add everything to the database when a new Incident is created, however I'm having difficulty with editing the Incident.
When the page loads for edit, I populate the form and then store the responses in the viewstate. When the user changes the list of responses (adds one, deletes one or edits one). I store this back into the viewstate. Then when the user clicks the save button, I'd like to save the changes to the Incident and the Responses back to the DB. I cannot figure out how to get the responses from the detached viewstate into the Incident object so that they can be updated together.
Currently when the user clicks save, I'm getting the Incident to edit from the db, making changes to the Incident's fields and then saving it back to the DB. However I can't figure out how to have the detached list of responses from the viewstate attach to the Incident. I have tried the following without success:
Clearning the Incident.Responses collection and adding the ones from the viewstate back in:
Incident.Responses.Clear() for each objResponse in Viewstate("Responses") Incident.Responses.add(objResponse) next Creating an EntityCollection from my list and then assiging that to the Incident.Responses Incident.Responses = EntityCollectionFromViewstateList Iterating through the responses in Incident.Response and assigning the corresponding object from viewstate: for each ObjResponse in Incident.Responses objResponse = objCorrespondingModifedResonseFromViewState Next
These all fail, I'd like to be able to merge the changes into the Inicdent object so that when the BLL calls SaveChanges on the changes to both the Incident and Responses will happen at the same time.
What I am trying to figure out is how to use a custom delimiter, single character or set of characters, to wrap a block of text inside a larger body of text and then pull that text out via regex. I have successfully done this with a single instance of wrapped text. If I have multiple instances, it blows up. Here is an example.
This would be my text block with the internally wrapped text:
[Code]....
When my current regex runs on this block, the greedy nature gives me a match starting with my first wrapped block delimeter and ending with my second wrapped block end delimeter. So my regex of @"#Delim(.*)#EndDelim" doesn't work in this instance. I am trying to figure out how to exclude the #EndDelim from my grouping. Simply using ([^#EndDelim]*) doesn't work as it tells regex to ignore the individual characters inside the brackets and not the actual word so this breaks if I have any of those characters inside my wrapped block of text.
I am probably making this harder than it needs to be. Does anyone know of a good solution or how to ignore entire words in regex?
i am using EF4 and StructureMap in an asp.net web application. I am using the repository/unit of work patterns as detailed in this post. In the code, there is a line that delegates the setup of an ObjectContext in global.asax.
EntityUnitOfWorkFactory.SetObjectContext(() => new MyObjectContext());
On the web page code-behind, you can create a generic repository interface like so ...
My question is what is a good approach to refactoring this code so that I can use more than one ObjectContext and differentiate between them in the code-behind? Basically i have two databases/entity models in my application and need to query them both on the same page.
I've scenerio where i've two dropdownlist box (one dependent on other, displays handset brand name and on selection displays the respective model name), two combolistbox which is bounded to their respective datasource(Displays the fault and accessories).
Now i've to update the three tables booking(Handsetid, Brand,model), accessories(handsetId,AcesoriesID) and fault(handsetID,faultID). Ive to update multiple rows in Accessories and fault.
These controls are present in datagridview EditTemplate
We have an ASP.NET MVC site that uses Entity Framework abstractions with Repository and UnitOfWork patterns. What I'm wondering is how others have implemented navigation of complex object graphs with these patterns. Let me give an example from one of our controllers:
[code]....
It's a registration process and pretty much everything hangs off the POCO class Person. In this case we're caching the person through the registration process. I've now started implementing the latter part of the registration process which requires access to data deeper in the object graph. Specifically DPA data which hangs off Legal inside Country.
The code above is just mapping out the model information into a simpler format for the ViewModel. My question is do you consider this fairly deep navigation of the graph good practice or would you abstract out the retrieval of the objects further down the graph into repositories?
Does anyone have a working pattern for converting a GET-POST-GET pattern to asny?
I'm encountering the following issues:
1. You cannot mix Sync and Async action methods SubmitForm(), SubmitFormAsync(bool? confirm), SubmitFormCompleted() ... (because the resolver gets all confused ... it doesn't use the HTTP verb to decide who to target. BTW: I think that's poor design, or a bug)
2. Renaming the get method name to something else eg: SubmitFormConfirmation(), SubmitFormAsync(bool? confirm), SubmitFormCompleted() would be very awkward if it works ... because you have to doctor the <form markup to specify an action name.
3. You cannot give them all async names SubmitFormAsync(), SubmitFormAsync(bool? confirm), submitFormCompleted(), because the call just keeps malfunctioning. It sometime even behaves as if you are requesting a delete of something.
Can someone give an insight from an actually working sample.
Now that the next version of ASP.NET MVC is being prototyped and previewed (ASP.NET MVC 3 Preview 1 came out a couple of weeks ago), I wonder if we should call the attention of the Core Dev team (S Hanselman, Phil Haack and all) to this "feature."there a easy/non tacky way of associating subdomains → areas?Something like: [URL]Also, whats the best accepted design pattern in implementing PRG pattern in ASP.NET MVC? I guess it should also get some official loving in MVC 3.
I was wondering if it is possible to map multiple DTO objects to a single ViewModel object using Automapper?
Essentially, I have multiple DTO objects and would like to display information from each on a single screen in ASP.NET MVC 2.0. To do so I would like to flatten the DTO objects (or parts of them...) into the Viewmodel and pass said viewmodel to the view. If I had one DTO this would be easy, but I've never seen it being done with multiple. Obviously there are a number of roundabout ways to do this (outside of automapper), but this is the approach that I would like to take if possible.
I have a form which I use to create an issue. WHen you post the form, the form elements are that of a custom DTO. The DTO is then used on my POST method to create the new entity. That all works fine.
However, I want to add the functionality to add multiple issues at the same time from the same view. In effect, the user would click something like 'Report Additional Problem', and an extra set of form fields would appear (I will like use jquery for this, which I don't have an issue with). However, even with just leaving one set of form fields, the user should still be able to create just one issue. But if I habve my post method take a list or array of my DTO, it doesn't work.
Here is the post method before editing:
[Code]....
What I want to do is for this to take an array or list of NewIssueDto. I would then loop through each one in the list and create a new issue from it.
<p>Hi</p> <p>I'm a newbie in MVC but a veteran web forms developer. I really like the idea of strongly typed views but what if I have multiple objects to pass to my razor view. Would I then NOT use strongly typed views and just use the ViewBag?</p>
since asp.net contains multiple threads that are executing at the same time.so if 2 threads access an object (simple or complex) that i got from the the asp.net httpcontext Cache.can't this lead to state problems on that object if these 2 theads tried to modify/read it at the same time?so what kind of precautions should i implement?for example i am thinking maybe locking the object while working with it? (wont this cause performance problems?)or maybe when i retrieve some object from the cache i should create a copy from it? or maybe i dont need to worry about this issue at all?
I'm trying to use the AutoComplete feature of JQuery to update multiple fields on an ASP.NET web page. The individual textbox is functioning perfectly, but I cannot figure out how to update multiple textboxes on the page once the user selects.
I've read many suggestions here that state I need to implement a result handler, but my intellisense is not showing that as an option, and IE I get a JS error saying that the object doesn't support this method.
I am linking to jquery-1.4.2.min.js and jquery-ui-1.8.5.custom.min.js .Here's my code:
