I'm got 2 model objects. Category and CategoryItem. I try to add a CategoryItem to Category in my Controller but It wont save to database, and I know why because I don't know how to call the submitChanges on the add while using repository, I dont got the DBContext right there is you know what I mean?.. here I will show you with code.
[Code]....
I am not familiar much with linqtoSQL and I need a better way to write this code:
[Code]....
[Code]....
I was trying to delete records from database and sometimes on production, the SubmitChanges() goes through and updates the associated entities yet the data does not gets deleted in the database.This is happening only in production and I could not replicate the same on stage or on my local machine. Now the table in which I am performing the delete transaction does have primary keys.
My code reads like
[Transactional(TransactionalTypes.TransactionScope)]
im developing a silverlight project using silverlight 3, vs2008 and linq2sql. when projects starts, im storing all the data from database into some static list variables. so when ever i need data, im reading it from those static list variables. all i want to know is, is it good to store data in static list variables and use it when ever necessary or is it good to get data directly from DataClassesDataContext object like db.mytable. which is the rite and fastest way or retrieving data. i mean which will use less connections to database?
View 2 RepliesI am confused about why I would need to wrap the DataContext's SubmitChanges within a transactionScope when modifying multiple tables. I was under the impression that the DataContext would track these changes and would therefore create its own transaction if need be.
In other words, if a change was made to update table A, B and C or if I made changes to 10 out of 20 items in a collection of rows, that the datacontext would track these changes and create its own transaction. If that is correct then why have I seen examples that wrapped these types of updates in a TransactionScope?
I am working on a page which display a gridview of members in a household. There are also other inputs for the entire household and one button at the bottom of the page that is intended to save the changes, or insert a new household depending on the situation. The number of rows is dynamic and the user can add and remove displayed rows. This is fine for a new household, but on an existing one I need it to delete the member from the household. I can do this easily right away, but I'm wondering if there is a way I can save or store the pending changes, basically the deleteonsubmit, insertonsubmit, and updates, till I call the submitchanges method when the user clicks save. That way if they change their mind about the changes, say the delete a member or an income they
View 1 RepliesCould someone explain what happens to the Repositories that are created when they are no longer needed? Are they automatically disposed of, or should we dispose of them manually?
Using EF4 as the DAL, to keep the program efficient I have been building repositories for the Model that abstract the data needed for specific views or actions. I have also used the Iinterface for the methods and call them in the Controller to pass them to the View. At some point the program needs to pass a behavior or request that requires the creation of a new repository and the process may repeat itself over and over again. What happens to the repositories that created for previous views, but are no longer needed? Should the dispose be written into each repository, or does garbage collection take care of this? How should this handled?
I've been reading up on MVC 2 and the recommended patterns, so far I've come to the conclusion (amongst much hair pulling and total confusion) that:
Model - Is just a basic data container Repository - Provides data access Service - Provides business logic and acts as an API to the Controller
The Controller talks to the Service, the Service talks to the Repository and Model. So for example, if I wanted to display a blog post page with its comments, I might do:
post = PostService.Get(id);
comments = PostService.GetComments(post); Or, would I do:
post = PostService.Get(id);
comments = post.Comments;
If so, where is this being set, from the repository? the problem there being its not lazy loaded.. that's not a huge problem but then say I wanted to list 10 posts with the first 2 comments for each, id have to load the posts then loop and load the comments which becomes messy.All of the example's use "InMemory" repository's for testing and say that including db stuff would be out of scope. But this leaves me with many blanks, so for a start can anyone comment on the above?
UML and Patterns: An Introduction to Object-Oriented Analysis and Design and Iterative Development, that follows the UP(Unified Process). It uses a Grasp Controller pattern to interact with domain classes by some methods like NewSale(), AddNewItemToSale() and CloseSale. In windows form, I can instantiate a object of this class in the UI and then use its methods to perform the actions. This works well in Client apps, but when I use asp.net mvc, I cannot find a way to instantiate an object (one for each user) that was always visible for a Controller (MVC). I cannot insert as an attribute inside Controller because it always create a new one.
View 1 RepliesI'm wondering about if there is a difference (in performance) when I use:
User usr = (from u in Adapter.User
where u.Login == login
select u).FirstOrDefault();
or
User usr = Adapter.getUserByLogin(login); //stored procedure
I would like to start a debate on traditional repositories versus one built on the UnitOfWork pattern. In a traditional repository, we wrap inserts, updates and deletes in a transaction, but selects don't really need them. In addition, nhibernate configuration is typically done once per application due to BuildSessionFactory being rather expensive. We often have several repositories of this type (one per aggregate chain). We also need to have projected, ahead of time, exactly what kinds of queries we'll need in order to build the interfaces and concretes correctly. In a single UnitOfWork repository we have the ability to manage both the current session and transaction, perform several operations, and then commit any changes all at once. In such a repository we may opt to put our configuration in the constructor since (typically speaking) no more than one Action is called per request anyway, initializing it in the application doesn't seem like much of an overall gain in speed. I must admit, I'm very temped to use the UnitOfWork pattern, as the following code looks really nice to me:
Csharp Code:
using (IUnitOfWork worker = new UnitOfWork()){// session and transaction are now both set
// save changes to three itemsworker.SaveOrUpdate(item1);worker.SaveOrUpdate(item2);worker.SaveOrUpdate(item3);
// grab a fourth var item4 = worker.Criteria<Foo>().Add(Expression.Eq("title", title)).UniqueResult<Foo>();
// delete the fourthworker.Delete(item4);
// all pending operations are commited or rolled back as a single unit (if one fails, all are rolled back), and then disposed, along with the session}
My proposed UnitOfWork class is rather simple. It implements IDisposable where I use a try-catch-finally in Dispose() to attempt a tx.Commit(), doing a tx.Rollback on failure, and a cleaning everything up in the finally clause. It also exposes common things like SaveOrUpdate, Delete, GetAll, Get, and even a Critera<T>() for custom on-the-spot queries. So what are your thoughts on this? I'd really like to hear about your experience with this pattern.
In a typical business application, a session is started and persisted across several pages. It is commited only when the transaction is complete. A good example of this is a tax preparation application. Once the session is started, it is persisted through session, cookies, or both. Nothing is written to file, or database, until the entire profile is complete and the refund/return is calculated. In such an ennvironment, is makes a great deal of sense to work with the structure imposed by domain driven design, and using a single repository to simple commit the session. However, there are times when this doesn't translate correctly, even when domain driven design is used.
An example of this is my forum project. While the entities themselves are good targets for domain driven design, I am not sure about the repositories. The basic structure is that a Category has many Forums, a Forum has many Threads, and a Thread has many posts. There are other things in there, but that's enough to describe what I want to get across. If a user has navigated to /Thread/Edit/42, and they have rights to edit it, all I am concerned about is fetching that record and displaying it. On postback, all I want is to be able to save it..................
Assuming my application did not warrant a full blown DDD setup, would Repositories still be useful? I like the way they shield from implementation details (such as use of Entity Framework) underneath. However Repositories tend to be tied to Aggregate Roots (the concept is still a holy grail to me) by definition.
I suppose the question could also be put as such: if I have a typical 3-tier application, with a business layer facade consisting of "logical grouping" classes based on functionality (rather than aggregate roots as in DDD) such as TradingManager and ContactsManager, would it make sense to also create "logical grouping" repositories. Or perhaps a Data Access Object, which I believe is like a Repository without the aggregate root requirement. Of course I will still have a Model (EF POCOs) that will be passed up and down between the layers.
Also, is what I just described would be considered as a Transaction Script approach? It's certainly not DDD, and not Active Record. I'm not even sure if Active Record exists with EF4 like it does with Nhibernate.
I am trying to understand how others structure n-layered applications when they do not follow DDD.
I have a couple of tables I ported over to a new database. Everything is exactly the same from the legacy one to the new one. The back-end code that submits the user generated data to the database is also the same. When I submit changes to the database, all of the submitted information populates the correct columns but the column that stores the GUID populates with all 0's. When I enter in the columns manually using SQL Server Management Studio, the GUID gets populated as it does in the legacy version.
View 2 RepliesAre there advantages in creating complex types in EF4 Entities and then use the complex properties in the repositories; instead of creating the aggregates in the the repository themselves? I.e. If the customer repository consists of properties of 3 entities: customers, addresses, email would it make sense to create a complex type consisting of the address and email properties, and add them as a complex property of the customer entity then just call the customer entity and the complex property in the repository, rather than just creating the repository class and aggregate the entities in the repository.What are there advantages or disadvantages in doing this in a MVC3 application?
View 10 RepliesI have a few repositories in my project. All repositories inherit from an abstract interface repository containing the public datacontext variable and a Save function for the entire DB.
In my controllers I want to make changes to the the db and in one of my functions I'm working with two different repositories. Calling the Save function on each of the repositories I'm using can cause a situation in which one of the calls to Save succeeds and and the other fails resulting in a need of rolling back the changes of the Save function that failed.
What is the best way to work against multiple repositories and access to the DB to avoid such a situation?
Don't know if this is possible, but i have a site with categories, when you click a category i want it to redirect to the same page, but with a querystring parameter of the category id. The page will then load a lightbox to open the images with the correct category id. That is my basic thought. if any1 has a better ide, i'll gladly listen. Dont worry about the linq2sql parts, that i am sure how to do.
View 1 RepliesIn my 2nd ASP.NET MVC project I'm facing a very weird problem: when I call the SubmitChanges method of the DataContext class, nothing updates in the database. It's weird because everything works fine with my first project. I'm using a remote database created in Sql Server Management Studio, I tried doing some queries there and in Visual Studio 2010 (where I have the connection to the database), they all work. Where might the problem be hidden?
DBDataContext DB = new DBDataContext();
var myuser = DB.Users.Single(u => u.ID == id);
myuser.Age = 45;
DB.SubmitChanges();
This is embarrassing :D Indeed I didn't have a primary key. Now it works!
I am running through this tutorial on ASP.NET MVC: [URL] Everything seemed to be going fine. I created my DB, created my Model classes, created a controller class and then started creating some Action handlers. When I finally created the page that submits updates to the DB, I got the following error:
System.NotImplementedException: The method or operation is not implemented.
Line 49: public void Save()Line 50: {Line 51: db.SubmitChanges();Line 52: }
when I call the "SubmitChanges()" method of the DataContext class. I tried recreating my DBML file from my tables, but I still get the same error.
The ASP.NET linq SubmitChanges method commits changes for all previous database modifications since the last time it was called.
I have a case where I do something like the following:
ClassX x = new Abc.Linq.ClassX();
DataContext.InsertOnSubmit(x);
ClassY y = new Abc.Linq.ClassXY();
DataContext.InsertOnSubmit(y);
DataContext.SubmitChanges();//x and y are committed to the database
I would like to insert y but not X in the line above. Then I would like to insert X with another call to SubmitChanges() sometime later. I have to execute the code in the order shown.
Is that possible?
I am working on a content management system which is being sort of retrofitted onto an existing database, and the database has many many tables. There will be a staging database, where we will make changes and allow users to 'preview in place'. Then any changes have to be approved, and to publish them we will connect to a live version of the same database (same schema) and play-forward the captured changes.I have found some code (called Doddle Audit) which, with some customization, is giving me great information about what is changing. I am able to get a list of all columns, before and after, for updates, inserts, and deletes. But what I would really like to have is the underlying SQL being run by SubmitChanges(). LinqToSql has to generate this, so why can't I have it? I have googled around and looked at code involving SubmitChanges, mousing over stuff, and I can't seem to find it. Does anyone know of a way to obtain this?
View 4 RepliesI'm building a music voting application, similar to stack overflow almost.I have 3 tables, Charts, ChartItems, Votes.I'm trying to bring back a list of chartitems, which link to a single chart, with the number of votes for each chart item counted.This is what I am trying currently
var firstList = from chartItem in db.ChartItems
join vote in db.Votes on chartItem.ixChartId equals vote.ixChartId into j1
where chartItem.ixChartId == id[code]...
The problem is once I have performed the grouping, I can't get any of the other properties I need from the join to populate the model. For example each ChartItem should have a title, id etc...I have created a ViewModel to hold all the properties that I need, called ChartItemWithVotes(includes all entity values + int totalVotes)In the end I am looking for this
Chart Name
Votes Name
20 - ChartItemname
15 - ChartItemname
12 - ChartITemName
Im using LINQ2SQL and i have an object called Article. Its has 2 properties FinishText and SwedishText. The idea is to let the user choose language. Swedish is default.
I bind the objects to a listView and there is a label that takes the swedish language. When the user presses the Finish flag button i want the objects to reload and the finish text to show instead of the swedish. The problem is that the text label is bound to the SwedishText property in the mark up like this:
<%#DataBinder.Eval(Container.DataItem, "SwedishText")%>
I can think of some ways to solve this, and i have one that doesnt work that well. My question is, what would be a good way to solve this? Im not so experienced so i know that there are lots of you out there that know how to do this much better.
Another problem i dont like my solution to is when i have an object that has a association with my Article object, like ArticleCategory. The ArticleCategoryId of my Article is, lets say 31, which is corresponds to the category "Movies". I dont want to display the category id but rather the name of the category itself (Movies).
So this is what i do:
<%#GetCategoryNameFromId(DataBinder.Eval(Container.DataItem, "Article_Id"))%>
I call a method that recreates the artice object and from there creates the ArticleCategory and gets the name from it. Its a horrible solution cause it involves lots of trips to the Database. Especially since i do similar things with other properties.
Just wanted to hear what is a proper and good way to deal with these common but for me new tasks.
As a new developer I'm getting thoroughly confused by naming and structural conventions for developing c# code using best practice.I appreciate it's perhaps applicable to each domain I am developing for but I've seen the code of many different open source projects and there seems to be a common theme. The successful projects have well thought out structure for maintenance and extensibility.The terms context, service, repository and controllers are used often and I wondered if these are open to interpretation or is there a consensus or convention on what, where or how these get used.
In an e-commerce platform I've seen there are order services, order contexts, customer repositories and product controllers for example. What should they do based on these names? Does a controller do something different to a service? When should you use a context? Is there a convention for namespaces? It's mind boggling when you try and push from a spoon fed newbie developer and try to move on.What software/tools should I really be looking at to develop quality code? Unit Testing, Continous Integration, Resharper, Mocking tools, DOI Containers, nHibernate.
I'm not really aware of blogs/books that will help me push on from being a proficient web developer into someone who can develop extensible, quality and testable code. There are big gaps in authors assumptions. You are either a newbie or a software architect. I want to push from being a junior developer with a long term aim of being a software architect. I realise it's all about patterns and practices but where are the training materials? I work on my own so don't have the opportunity of learning from others.
want to know if linq to sql auto updated the id column of a class (table row object) after SubmitChanges is called inserting a new row to that table, that would be fantastic, would anyone be able to confirm this?
View 2 Replies