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  • ASP MVC C#: LINQ Foreign Key Constraint conflicts

    - by wh0emPah
    I'm having a problem with LINQ. I have 2 tables (Parent-child relation) Table1: Events (EventID, Description) Table2: Groups (GroupID, EventID(FK), Description) Now i want to create an Event an and a child. Event e = new Event(); e.Description = "test"; Datacontext.Events.InsertOnSubmit(event) Group g = new Group(); g.Description = "test2"; g.EventID = e.EventID; Datacontext.Groups.InsertOnSubmit(g); Datacontext.SubmitChanges(); When i debug, i can see that after inserting the event. the EventID has gotten a new value (auto increment). But when Datacontext.SubmitChanges(); gets called. I get the following exception "The INSERT statement conflicted with the FOREIGN KEY constraint ... I know this can be solved by creating a relation in the LINQ diagram between Events and groups. And then setting the entity itself. But i don't want to load the events everytime i ask a list of groups. All i need is some way that when inserting the group fails, the event insert won't be comitted in the database. Sorry if this is a bit unclear, My english isn't really good. Thanks in advance!

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  • Cannot attach an entity that already exists.

    - by coure06
    i am trying to update code via Linq, but getting this error Cannot attach an entity that already exists. C# code is here var con = (from c in cmsContentTable where c.ContentName == contentId select c).FirstOrDefault(); cmsContentTable.Attach(con); con.ContentData = "New Value"; cmsContentTable.Context.SubmitChanges();

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  • Database design - alternatives for Entity Attribute Value (EAV)

    - by Bob
    Hi, see http://stackoverflow.com/questions/695752/product-table-many-kinds-of-product-each-product-has-many-parameters for similar topic. My question: i want to design a database, that will be used for a production facility of different types of products where each product has its own (number of) parameters. because i want the serial numbers to be in one tabel for overview purposes i have a problem with these different paraeters . One solution could be EAV, but it has its downsides, certainly because we have +- 5 products with every product +- 20.000 serial numbers (records). it looks a bit overkill to me... I just don't know how one could design a database so that you have an attribute in a mastertable that says: 'hey, you could find details of this record in THAT detail-table". 'in a way that you qould easely query the results) currenty i am using Visual Basic & Acces 2007. but i'm going to Visual Basic & MySQL. thanks for your help. Bob

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  • LoginView inside FormView control is not databinding on PostBack

    - by subkamran
    I have a fairly simple form: <asp:FormView> <EditItemTemplate> <asp:LoginView> <RoleGroups> <asp:RoleGroup roles="Blah"> <ContentTemplate> <!-- Databound Controls using Bind/Eval --> </ContentTemplate> </asp:RoleGroup> </RoleGroups> </asp:LoginView> <!-- Databound Controls --> </EditItemTemplate> </asp:FormView> <asp:LinqDataSource OnUpdating="MyDataSource_Updating" /> I handle my LinqDataSource OnUpdating event and do some work handling some M:N fields. That all works. However, once the update is finished (and I call e.Cancel = true), the LoginView control does not databind its children... so they are all blank. The FormView's viewstate is still fine, as all the rest of the controls outside of the LoginView appear fine. I even handle the FormView_DataBound event and a Trace shows that the FormView is being databound on postback. Why then is the LoginView not keeping its ViewState/being databound? Here's a sample code snippet showing the flow: protected void MyDataSource_Updating(object s, LinqDataSourceUpdateEventArgs e) { try { Controller.DoSomething(newData); // attempts to databind again here fail // frmView.DataBind(); // MyDataSource.DataBind(); // LoginView.DataBind(); } catch { // blah } finally { e.Cancel = true; } }

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  • Are soft deletes a good idea?

    - by Khou
    Are soft deletes a good idea or a bad idea? Instead of actually deleting a record in your database, you would just flag it as "IsDeleted" = true, and upon recovery of the record you could just flag it as "False". Is this a good idea?

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  • How can I write a clean Repository without exposing IQueryable to the rest of my application?

    - by Simucal
    So, I've read all the Q&A's here on SO regarding the subject of whether or not to expose IQueryable to the rest of your project or not (see here, and here), and I've ultimately decided that I don't want to expose IQueryable to anything but my Model. Because IQueryable is tied to certain persistence implementations I don't like the idea of locking myself into this. Similarly, I'm not sure how good I feel about classes further down the call chain modifying the actual query that aren't in the repository. So, does anyone have any suggestions for how to write a clean and concise Repository without doing this? One problem I see, is my Repository will blow up from a ton of methods for various things I need to filter my query off of. Having a bunch of: IEnumerable GetProductsSinceDate(DateTime date); IEnumberable GetProductsByName(string name); IEnumberable GetProductsByID(int ID); If I was allowing IQueryable to be passed around I could easily have a generic repository that looked like: public interface IRepository<T> where T : class { T GetById(int id); IQueryable<T> GetAll(); void InsertOnSubmit(T entity); void DeleteOnSubmit(T entity); void SubmitChanges(); } However, if you aren't using IQueryable then methods like GetAll() aren't really practical since lazy evaluation won't be taking place down the line. I don't want to return 10,000 records only to use 10 of them later. What is the answer here? In Conery's MVC Storefront he created another layer called the "Service" layer which received IQueryable results from the respository and was responsible for applying various filters. Is this what I should do, or something similar? Have my repository return IQueryable but restrict access to it by hiding it behind a bunch of filter classes like GetProductByName, which will return a concrete type like IList or IEnumerable?

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  • Build and render infinite hierarchical category tree from self-referential category table

    - by FreshCode
    I have a Categories table in which each category has a ParentId that can refer to any other category's CategoryId that I want to display as multi-level HTML list, like so: <ul class="tree"> <li>Parent Category <ul> <li>1st Child Category <!-- more sub-categories --> </li> <li>2nd Child Category <!-- more sub-categories --> </li> </ul> </li> </ul> Presently I am recursively rendering a partial view and passing down the next category. It works great, but it's wrong because I'm executing queries in a view. How can I render the list into a tree object and cache it for quick display every time I need a list of all hierarchical categories?

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  • Can a DevExpress XtraGrid be filled using a a Dynamic SELECT statement string

    - by Gerhard Weiss
    Can a DevExpress XtraGrid be filled using a a Dynamic SELECT statement string? i.e. SELECT * FROM Employee or SELECT * FROM Dependents To fill our XtraGrids currently, we use a ORM that creates entities. To do this it takes a lot of steps and time. What is driving me to ask this question is we do a lot of client aquistions where we get hundreds of files. I do not want to create entities for all of these then have to create an XtraGrid for each entity. Ideally if I can just feed it a SELECT statement and the XtraGrid could render it then I could use the XtraGrid very nice data minipulation features (Filter, Group By, etc). If you have any other ideas or suggestions please to not hesitate to post them.

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  • Can't enter to webadmin in godaddy mssql

    - by gon009
    I just pay for the deluxe plan in godaddy for my website but I have a problem, I created the database in mssql and when I click to webadmin ,it redirects me to: http://mssql.myname.com/silentlogon.aspx with the message: This webpage is not available. But if I create a mysql database everything is ok, idk what I am doing wrong , I know I cant contact GoDaddy but the line is busy or when I talk to them they don't understand. Thanks four your time and help :)

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  • Sharepoint OLE DB - field not updateable

    - by Pandincus
    I need to write a simple C# .NET application to retrieve, update, and insert some data in a Sharepoint list. I am NOT a Sharepoint developer, and I don't have control over our Sharepoint server. I would prefer not to have to develop this in a proper sharepoint development environment simply because I don't want to have to deploy my application on the Sharepoint server -- I'd rather just access data externally. Anyway, I found out that you can access Sharepoint data using OLE DB, and I tried it successfully using some ADO.NET: var db = DatabaseFactory.CreateDatabase(); DataSet ds = new DataSet(); using (var command = db.GetSqlStringCommand("SELECT * FROM List")) { db.LoadDataSet(command, ds, "List"); } The above works. However, when I try to insert: using (var command = db.GetSqlStringCommand("INSERT INTO List ([HeaderName], [Description], [Number]) VALUES ('Blah', 'Blah', 100)")) { db.ExecuteNonQuery(command); } I get this error: Cannot update 'HeaderName'; field not updateable. I did some Googling and apparently you cannot insert data through OLE DB! Does anyone know if there are some possible workarounds? I could try using Sharepoint Web Services, but I tried that initially and was having a heck of a time authenticating. Is that my only option?

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  • Use a stored procedure parameter for unit parameter of DATE_SUB

    - by Mike
    I would like to know if it's possible to pass a parameter to a mysql stored procedure and use this parameter as the unit parameter of the DATE_SUB function. It seems that the unit parameter is a reserved word so I don't know if there's a type for unit. Exemple of what I'm trying to do : DELIMITER $$ DROP PROCEDURE IF EXISTS `test` $$ CREATE DEFINER=`root`@`%` PROCEDURE `test`(param1 unit) BEGIN select DATE_SUB(now(), INTERVAL 1 param1); END $$ DELIMITER ;

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  • Sorting Anonymous Types

    - by strobaek
    I have a question of how to sort an anonymous type. Using Linq2SQL I have the following query, which returns a list of submissions: var submissions = EventSubmissions .Where(s => s.EventId.Equals(eventId)); Consider the following interface (somewhat simplyfied): public interface IQuerySorter { IOrderedQueryable Sort(IQueryable query); IOrderedQueryable<T> Sort<T, U>(IQueryable<T> query, Expression<Func<T,U>> selector); ... } Using this interface allows me to implement a number of 'sorters', e.g. on Date, Rating or whether or not a submission has been nominated (for voting). sortedQuery = sorter.Sort(submissions) So far so good. A submission can be made "votable". I get the number of votes a nominated submission may have using the following query: var withVoteCount = submissions .Select(s => new {NumberOfVotes = s.Votes.Count(), Submission = s}); I would like to sort this new query by NumberOfVotes using my "general" sorter class, but run into the problem that the anonymous type/member does not seem to live outside the repository-method, hence I am unable to sort on it. Any input would be greatly appreciated.

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  • Opinions on sensor / reading / alert database design

    - by Mark
    I've asked a few questions lately regarding database design, probably too many ;-) However I beleive I'm slowly getting to the heart of the matter with my design and am slowly boiling it down. I'm still wrestling with a couple of decisions regarding how "alerts" are stored in the database. In this system, an alert is an entity that must be acknowledged, acted upon, etc. Initially I related readings to alerts like this (very cut down) : - [Location] LocationId [Sensor] SensorId LocationId UpperLimitValue LowerLimitValue [SensorReading] SensorReadingId Value Status Timestamp [SensorAlert] SensorAlertId [SensorAlertReading] SensorAlertId SensorReadingId The last table is associating readings with the alert, because it is the reading that dictate that the sensor is in alert or not. The problem with this design is that it allows readings from many sensors to be associated with a single alert - whereas each alert is for a single sensor only and should only have readings for that sensor associated with it (should I be bothered that the DB allows this though?). I thought to simplify things, why even bother with the SensorAlertReading table? Instead I could do this: [Location] LocationId [Sensor] SensorId LocationId [SensorReading] SensorReadingId SensorId Value Status Timestamp [SensorAlert] SensorAlertId SensorId Timestamp [SensorAlertEnd] SensorAlertId Timestamp Basically I'm not associating readings with the alert now - instead I just know that an alert was active between a start and end time for a particular sensor, and if I want to look up the readings for that alert I can do. Obviously the downside is I no longer have any constraint stopping me deleting readings that occurred during the alert, but I'm not sure that the constraint is neccessary. Now looking in from the outside as a developer / DBA, would that make you want to be sick or does it seem reasonable? Is there perhaps another way of doing this that I may be missing? Thanks. EDIT: Here's another idea - it works in a different way. It stores each sensor state change, going from normal to alert in a table, and then readings are simply associated with a particular state. This seems to solve all the problems - what d'ya think? (the only thing I'm not sure about is calling the table "SensorState", I can't help think there's a better name (maybe SensorReadingGroup?) : - [Location] LocationId [Sensor] SensorId LocationId [SensorState] SensorStateId SensorId Timestamp Status IsInAlert [SensorReading] SensorReadingId SensorStateId Value Timestamp There must be an elegant solution to this!

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  • SubSonic missing stored procedures in StoredProcedures.cs when generated with SubCommander sonic.exe

    - by Mark
    We have been using SubSonic to generate our DAL with a lot of success on VS2005 and SubSonic Tools 2.0.3. SubSonic Tools do not work on VS2008 (as far as we can work out) so we have tried to use SubCommander\sonic.exe and are now hitting some problems. When we regenerate the project using SubCommander\sonic.exe and try to compile we get some errors reporting missing members (which should have been automatically generated based on the stored procedures we have). On closer inspection it looks like my StoredProcedures.cs file is missing some (not all) automatically generated methods for my classes. As an example, I have 2 procs: [dbo]._ClassA_Func1 [dbo]._ClassA_Func2 Only one of these is being generated in the StoredProcedures.cs file. These methods generate fine using the SubSonic Tools plugin. We have tried now with versions 2.1 and 2.2 of SubSonic with the same issue. We are still on .NET 2.0 so cannot use SubSonic 3.0. I have checked the permissions of both procs using fn_my_permissions and they seem identical. Does anyone have any ideas on what I can check? Thanks -- Mark

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  • Linq - how does it work??

    - by clarkeyboy
    Hey, I have just been looking into Linq with ASP.Net. It is very neat indeed. I was just wondering - how do all the classes get populated? I mean in ASP.Net, suppose you have a Linq file called Catalogue, and you then use a For loop to loop through Catalogue.Products and print each Product name. How do the details get stored? Does it just go through the Products table on page load and create another instance of class Product for each row, effectively copying an entire table into an array of class Product? If so, I think I have created a system very much like this, in the sense that there is a SiteContent module with an instance of each Manager class - for example there is UserManager, ProductManager, SettingManager and alike. UserManager contains an instance of the User class for each row in the Users table. They also contain methods such as Create, Update and Remove. These Managers and their "Items" are created on every page load. This just makes it nice and easy to access users, products, settings etc in every page as far as I, the developer, am concerned. Any any subsequent pages I need to create, I just need to reference SiteContent.UserManager to access a list of users, rather than executing a query from within that page (ie this method separates out data access from the workings of the page, in the same way as using code behind separates out the workings of the page from how the page is layed out). However the problem is that this technique seems rather slow. I mean it is effectively creating a database on every page load, taking data from another database. I have taken measures such as preventing, for example, the ProductManager from being created if it is not referenced on page load. Therefore it does not load data into storage when it is not needed. My question is basically whether my technique does the exact same thing as Linq, in the sense of duplicating data from tables into properties of classes.. Thanks in advance for any advice or answers about this. Regards, Richard Clarke

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  • ASP.NET MVC pagination problem????

    - by MD_Oppenheimer
    OK, This is starting to get mildly irritating. I tried to implement Twitter style paging using ASP.NET MVC and JQuery my problem is that when not using Request.IsAjaxRequest() (for users with javascript turned off) it works fine, obviously posting back the whole page. when I run the code for Request.IsAjaxRequest(), it skips entries, and does not return result in order. this is the code I have: public ActionResult Index(int? startRow) { StatusUpdatesRepository statusUpdatesRepository = new StatusUpdatesRepository(); if (!startRow.HasValue) startRow = Globals.Settings.StatusUpdatesSection.StatusUpdateCount;//5 Default starting row //Retrieve the first page with a page size of entryCount int totalItems; if (Request.IsAjaxRequest()) { IEnumerable<StatusUpdate> PagedEntries = statusUpdatesRepository.GetLastStatusUpdates(startRow.Value,Globals.Settings.StatusUpdatesSection.StatusUpdateCount, out totalItems); if (startRow < totalItems) AddMoreUrlToViewData(startRow.Value); return View("StatusUpdates", PagedEntries); } //Retrieve the first page with a page size of global setting // First run skip 0 take 5 IEnumerable<StatusUpdate> entries = statusUpdatesRepository.GetLastStatusUpdates(0,startRow.Value, out totalItems); if (startRow < totalItems) AddMoreUrlToViewData(startRow.Value); return View(entries); } private void AddMoreUrlToViewData(int entryCount) { ViewData["moreUrl"] = Url.Action("Index", "Home", new { startRow = entryCount + Globals.Settings.StatusUpdatesSection.StatusUpdateCount }); } My GetLastStatusUpdates function: public IQueryable GetLastStatusUpdates(int startRowIndex, int maximumRows,out int statusUpdatesCount ) { statusUpdatesCount = db.StatusUpdates.Count(); return db.StatusUpdates .Skip(startRowIndex) .Take(maximumRows) .OrderByDescending(s = s.AddedDate); } Really fresh out out of ideas as to why this is not working properly when responding to a Request.IsAjaxRequest(), ie when I turn of javascript in the browser, the code works perfectly, except I don't want to repost the whole page????

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  • Query that ignore the spaces.

    - by xRobot
    What's the best way to run a query so that spaces in the fields are ignored? For example the following queries.... SELECT * FROM mytable WHERE username = "JohnBobJones" SELECT * FROM mytable WHERE username = "John Bob Jones" . would find the following entries: John Bob Jones JohnBob Jones JohnBobJones . I am using php or python but I think this doesn't matter.

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  • Fill WinForms DataGridView From Anonymous Linq Query

    - by mdvaldosta
    // From my form BindingSource bs = new BindingSource(); private void fillStudentGrid() { bs.DataSource = Admin.GetStudents(); dgViewStudents.DataSource = bs; } // From the Admin class public static List<Student> GetStudents() { DojoDBDataContext conn = new DojoDBDataContext(); var query = (from s in conn.Students select new Student { ID = s.ID, FirstName = s.FirstName, LastName = s.LastName, Belt = s.Belt }).ToList(); return query; } I'm trying to fill a datagridview control in Winforms, and I only want a few of the values. The code compiles, but throws a runtime error: Explicit construction of entity type 'DojoManagement.Student' in query is not allowed. Is there a way to get it working in this manner?

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  • using securestring for a sql connection

    - by Rick
    Hi, I want to use a SecureString to hold a connection string for a database. But as soon as I set the SqlConnection object's ConnectionString property to the value of the securestring surely it will become visible to any other application that is able to read my application's memory? I have made the following assumptions: a) I am not able to instantiate a SqlConnection object outside of managed memory b) any string within managed memory can be read by an application such as Hawkeye

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  • Behaviour of insertion trigger when defining autoincrement in Oracle

    - by Genba
    I have been looking for a way to define an autoincrement data type in Oracle and have found these questions on Stack Overflow: Autoincrement in Oracle Autoincrement Primary key in Oracle database The way to use autoincrement types consists in defining a sequence and a trigger to make insertion transparent, where the insertion trigger looks so: create trigger mytable_trg before insert on mytable for each row when (new.id is null) begin select myseq.nextval into :new.id from dual; end; I have some doubts about the behaviour of this trigger: What does this trigger do when the supplied value of "id" is different from NULL? What does the colon before "new" mean? I want the trigger to insert the new row with the next value of the sequence as ID whatever the supplied value of "new.id" is. I imagine that the WHEN statement makes the trigger to only insert the new row if the supplied ID is NULL (and it will not insert, or will fail, otherwise). Could I just remove the WHEN statement in order for the trigger to always insert using the next value of the sequence?

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