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  • C# Sql Connection Best Practises 2013

    - by Pete Petersen
    With the new year approaching I'm drawing up a development plan for 2013. I won't bore you with the details but I started thinking about whether the way I do things is actually the 'correct' way. In particular how I'm interfacing with SQL. I create predominantly create WPF desktop applications and often some Silverlight Web Applications. All of my programs are very Data-Centric. When connecting to SQL from WPF I tend to use Stored Procedures stored on the server and fetch them using ADO.NET (e.g. SQLConnection(), .ExecuteQuery()). However with Silverlight I have a WCF service and use LINQ to SQL (and I'm using LINQ much more in WPF). My question is really is am I doing anything wrong in a sense that it's a little old fashioned? I've tried to look this up online but could find anything useful after about 2010 and of those half were 'LINQ is dead!' and the other 'Always use LINQ' Just want to make sure going forward I'm doing the right things the right way, or at least the advised way :). What principles are you using when connecting to SQL? Is it the same for WPF and Silverlight/WCF?

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  • System.Security.VerificationException: Operation could destabilize the runtime

    - by Rigobert Song
    I have a web service which is queried using linq to sql but returns an array of objects. I keep getting the following error: System.Security.VerificationException: Operation could destabilize the runtime When I run a method that uses a linq statement to return an array I get this error, but only on my test server, which is windows server 2008. Everything works fine in my win 7 machine. The project is a .net 3.5. Any ideas what the problem might be? Thanks UPDATE: My linq queries return IQueryable.

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  • What to put as the Provider for a mocked IQueryable

    - by Vaccano
    I am working with Moles and mocking a System.Data.Linq.Table. I got it constructing fine, but when I use it, it wants IQueryable.Provider to be mocked (moled) as well. I just want it to use normal Linq To Objects. Any idea what that would be? Here is the syntax I can use: MTable<User> userTable = new System.Data.Linq.Moles.MTable<User>(); userTable.Bind(new List<User> { UserObjectHelper.TestUser() }); // this is the line that needs help MolesDelegates.Func<IQueryProvider> provider = //Insert provider here! ^ userTable.ProviderSystemLinqIQueryableget = provider | | | what can I put here? ----------------------------------------+

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  • Access Edit Mode Values of BindingSource Control

    - by Christopher Edwards
    I have a BindingSource control (http://msdn.microsoft.com/en-us/library/system.windows.forms.bindingsource.aspx) with a datasource of a (single) Linq object. If I change any of the properties of the underlying Linq-to-Sql object then all the other changes on the bound controls on the form are lost. Does anyone now why and how I work around it? I don't want to call EndEdit because this will commit the changes to the underlying object. I think this might be because my underlying object linq-to-sql object does not implement IEditableObject so the potental new values for the object fields are sort of stored in the forms controls. Can anyone either clarify what is going on and/or suggest a work around. Thanks!

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  • Using LinqSql, stored procedure returns datatype image problem

    - by Elias
    Hello! I´ve got a problem when using LINQ to execute a stored procedure and return its values. One of the column that the stored procedure returns is of datatype image and contains a pdf in binary form.(this because the database is deployed on sql server 2000, otherwised i would choose a blob) When including the stored procedure in my linq class its generates that my pdf columns is datatype int in the designer class. I´ve work around the problem and manually changed the datatype in representation of the stored procedure in the designer class. But when adding/removing items in the linq class the designer file re-generates and my changes are lost. Are there any better solution for my problem??

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  • Building an application that includes a DB, and need recommendations

    - by Rubys
    I'm going to build a little system for personal use, and I want it to save data to a database. The language is going to be C#, and so I'd like to use this opportunity to get my head around LINQ to SQL. I have some DB experience and I know my SQL, but it was all in school using Access, which is giving me trouble, and so I'd like to use another DB, something that is small in size, easy to install, and should work with LINQ to SQL. The problem is: I don't know any except Access, and am looking for recommendations. To sum it up: I need a lightweight, easy to install, linq-to-sql supporting database for a small system on a home computer, any recommendations?

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  • LinqToSql: How can I create a projection to adhere to DRY?

    - by mhutter
    Just wondering if there is a way to take some of the repitition out of a LINQ to SQL projected type. Example: Table: Address Fields: AddressID, HouseNumber, Street, City, State, Zip, +20 more Class MyAddress: AddressID, HouseNumber, Street (Only 3 fields) LINQ: from a in db.Addresses select new MyAddress { AddressID = a.AddressID, HouseNumber = a.HouseNumber, Street = a.Street } The above query works perfectly, and I understand why something like this will return all 20+ fields in each row: from a in db.Addresses select new MyAddress(a); class MyAddress { public MyAddress(Address a) { this.AddressID = a.AddressID, this.HouseNumber = a.HouseNumber, this.Street = a.Street } } Which leads me to my Question: Is it possible to implement some kind of helper function or extension method to "map" from the LINQ model to MyAddress yet only return the necessary fields in the query result rather than all of the fields?

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  • How to get rid of this error in asp.net-mvc?

    - by Pandiya Chendur
    I am using Linq-to-sql as an ORM. I wrote this innerjoin public IQueryable<Material> FindAllMaterials() { var materials=from m in db.Materials join Mt in db.MeasurementTypes on m.MeasurementTypeId equals Mt.Id select new { m.Mat_id, m.Mat_Name, Mt.Name, m.Mat_Type }; return materials; } But when i compile this i got an error Cannot implicitly convert type 'System.Linq.IQueryable<AnonymousType#1>' to 'System.Linq.IQueryable<CrMVC.Models.Material>'. An explicit conversion exists (are you missing a cast?) Am i missing some thing... Any suggestion....

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  • How can I keep the the logic to translate a ViewModel's values to a Where clause to apply to a linq query out of My Controller?

    - by Mr. Manager
    This same problem keeps cropping up. I have a viewModel that doesn't have any persistent backing. It is just a ViewModel to generate a search input form. I want to build a large where clause from the values the user entered. If the Action Accepts as a parameter SearchViewModel How do I do this without passing my viewModel to my service layer? Service shouldn't know about ViewModels right? Oh and if I serialize it, then it would be a big string and the key/values would be strongly typed. SearchViewModel this is just a snippet. [Display(Name="Address")] public string AddressKeywords { get; set; } /// <summary> /// Gets or sets the census. /// </summary> public string Census { get; set; } /// <summary> /// Gets or sets the lot block sub. /// </summary> public string LotBlockSub { get; set; } /// <summary> /// Gets or sets the owner keywords. /// </summary> [Display(Name="Owner")] public string OwnerKeywords { get; set; } In my controller action I was thinking of something like this. but I would think all this logic doesn't belong in my Controller. ActionResult GetSearchResults(SearchViewModel model){ var query = service.GetAllParcels(); if(model.Census != null){ query = query.Where(x=>x.Census == model.Census); } if (model.OwnerKeywords != null){ query = query.Where(x=>x.Owners == model.OwnerKeywords); } return View(query.ToList()); }

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  • The member [class] has no supported translation to SQL

    - by Code Sherpa
    Hi, I am getting the following error: Error Message:The member 'Company.ProductCore.Core.Domain.Account.Email' has no supported translation to SQL. My method looks like this: public Account GetAccountByEmail(string email) { Account account; using (WorkbookDataContext dc = _conn.GetContext()) { account = ( from a in dc.Accounts join em in dc.Emails on a.AccountId equals em.AccountId where a.Email.EmailAddress == email select a).FirstOrDefault(); } return account; } My Account class has a getter / setter that exposes Email: public Email Email { get { return _email; } set { _email = value; } } And my Email is a LINQ object. I have a feeling that the problem is that I am using a LINQ object for me Email property? I am new to LINQ and am not really sure why this is happening. Help appreciated, thanks...

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  • MVC more specified models should be populated by more precise query too?

    - by KevinUK
    If you have a Car model with 20 or so properties (and several table joins) for a carDetail page then your LINQ to SQL query will be quite large. If you have a carListing page which uses under 5 properties (all from 1 table) then you use a CarSummary model. Should the CarSummary model be populated using the same query as the Car model? Or should you use a separate LINQ to SQL query which would be more precise? I am just thinking of performance but LINQ uses lazy loading anyway so I am wondering if this is an issue or not.

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  • Is Linq having a mind-numbing effect on .NET programmers?

    - by Aaronaught
    A lot of us started seeing this phenomenon with jQuery about a year ago when people started asking how to do absolutely insane things like retrieve the query string with jQuery. The difference between the library (jQuery) and the language (JavaScript) is apparently lost on many programmers, and results in a lot of inappropriate, convoluted code being written where it is not necessary. Maybe it's just my imagination, but I swear I'm starting to see an uptick in the number of questions where people are asking to do similarly insane things with Linq, like find ranges in a sorted array. I can't get over how thoroughly inappropriate the Linq extensions are for solving that problem, but more importantly the fact that the author just assumed that the ideal solution would involve Linq without actually thinking about it (as far as I can tell). It seems that we are repeating history, breeding a new generation of .NET programmers who can't tell the difference between the language (C#/VB.NET) and the library (Linq). What is responsible for this phenomenon? Is it just hype? Magpie tendencies? Has Linq picked up a reputation as a form of magic, where instead of actually writing code you just have to utter the right incantation? I'm hardly satisfied with those explanations but I can't really think of anything else. More importantly, is it really a problem, and if so, what's the best way to help enlighten these people?

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  • Using LIKE operator in LINQ to Entity

    - by Draconic
    Hi, everybody! Currently in our project we are using Entity Framework and LINQ. We want to create a search feature where the Client fills different filters but he isn't forced to. To do this "dynamic" query in LINQ, we thought about using the Like operator, searching either for the field, or "%" to get everything if the user didn't fill that field. The joke's on us when we discovered it didn't support Like. After some searching, we read several answers where it's sugested to use StartsWith, but it's useless for us. Is the only solution using something like: ObjectQuery<Contact> contacts = db.Contacts; if (pattern != "") { contacts = contacts.Where(“it.Name LIKE @pattern”); contacts.Parameters.Add(new ObjectParameter(“pattern”, pattern); } However, we'd like to stick with linq only. Happy coding!

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  • Dynamic Data: how to filter dropdown for foreign key on edit page

    - by Leonv
    I have Organisation with a foreign key to a Manager. Managers can be active, or inactive. On the Dynamic Data edit page for Organisation, I need to filter the dropdown for Manager to only show active records. I started out by making a custom version of DynamicData\FieldTemplates\ForeignKey_Edit.ascx and setting a UIHint to the new field template on Organisation.Manager. But, how to customize the linq or sql query that runs to load the Managers? Using Linq-to-SQL and DynamicDataFutures

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  • NLOG to output db.out

    - by Coppermill
    I would like to use nLog to output my LINQ to SQL generated SQL to the log file e.g. db.Log = Console.Out reports the generated SQL to the console, http://www.bryanavery.co.uk/post/2009/03/06/Viewing-the-SQL-that-is-generated-from-LINQ-to-SQL.aspx How can I get the log to log to NLOG?

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  • .NET database enumeration

    - by erasmus
    In a project, one of my entities is House which has many enumeration properties (for example housetype). Using .NET, Linq to Sql and Sql Server how can I create a db with enumeration and use it with Linq to Sql? What should be my approach?

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  • How to approach performance issues?

    - by jess
    Hi, We are developing a client-server desktop application(winforms with sql server 2008, using LINQ-SQL).We are now finding many issues related to performance.These relate to querying too much data with LINQ , bad database design,not much caching etc.What do you suggest,we should do - how to go about solving these performance issues? One thing,I am doing is doing sql profiling,and trying to fix some queries.As far caching is concerned,we have static lists.But,how to keep them updated,we don't have any server side implementation.So,these lists can be stale,if someone changes data. regards

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  • How do I get results from a link query in the order of IDs that I provide?

    - by Keltex
    I'm looking to get query results back from Linq in the order that I pass IDs to the query. So it would look something like this: var IDs = new int [] { 5, 20, 10 } var items = from mytable in db.MyTable where IDs.Contains(mytable.mytableID) orderby // not sure what to do here select mytable; I'm hoping to get items in the order of IDs (5, 20, 10). (Note this is similar to this question, but I would like to do it in Linq instead of SQL)

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  • c#: Design advice. Using DataTable or List<MyObject> for a generic rule checker

    - by Andrew White
    Hi, I have about 100,000 lines of generic data. Columns/Properties of this data are user definable and are of the usual data types (string, int, double, date). There will be about 50 columns/properties. I have 2 needs: To be able to calculate new columns/properties using an expression e.g. Column3 = Column1 * Column2. Ultimately I would like to be able to use external data using a callback, e.g. Column3 = Column1 * GetTemperature The expression is relatively simple, maths operations, sum, count & IF are the only necessary functions. To be able to filter/group the data and perform aggregations e.g. Sum(Data.Column1) Where(Data.Column2 == "blah") As far as I can see I have two options: 1. Using a DataTable. = Point 1 above is achieved by using DataColumn.Expression = Point 2 above is acheived by using DataTable.DefaultView.RowFilter & C# code 2. Using a List of generic Objects each with a Dictionary< string, object to store the values. = Point 1 could be achieved by something like NCalc = Point 2 is achieved using LINQ DataTable: Pros: DataColumn.Expression is inbuilt Cons: RowFilter & coding c# is not as "nice" as LINQ, DataColumn.Expression does not support callbacks(?) = workaround could be to get & replace external value when creating the calculated column GenericList: Pros: LINQ syntax, NCalc supports callbacks Cons: Implementing NCalc/generic calc engine Based on the above I would think a GenericList approach would win, but something I have not factored in is the performance which for some reason I think would be better with a datatable. Does anyone have a gut feeling / experience with LINQ vs. DataTable performance? How about NCalc? As I said there are about 100,000 rows of data, with 50 columns, of which maybe 20 are calculated. In total about 50 rules will be run against the data, so in total there will be 5 million row/object scans. Would really appreciate any insights. Thx. ps. Of course using a database + SQL & Views etc. would be the easiest solution, but for various reasons can't be implemented.

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  • Rewrite SQL Fulltext Function to return Table only

    - by Alex
    I have a MS SQL Fulltext Function like this: (...) RETURNS TABLE AS RETURN SELECT * FROM fishes INNER JOIN CONTAINSTABLE(fishes, *, @keywords, @limit) AS KEY_TBL ON fishes.id = KEY_TBL.[KEY] When I use this function in LINQ, it generates a special return type which includes all fields of my "fishes" table, plus Key and Rank. How could I rewrite above query, or change something in LINQ, to omit Key and Rank and just return my "fishes" results (and to have the fulltext search result objects be of type Fish, which is what I really care about, so I don't have to cast)?

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  • How to get an object from a list based upon IEqualityComparer<T>

    - by Greg
    The Compare method in Linq lets you find by an IEqualityComparer, but I can't find a counterpart method that allows you retrieve an item by the same comparer. Is this really the best way to do it? MyItem myFinderItem = new MyItem(keyField1, keyField2); if (myList.Contains(myFinderItem, new MyEqualityComparer())) { MyItem myRealItem = myList.Single(item => new MyEqualityComparer().Equals(item , myFinderItem)); } (I'm sharing the usage of the IEqualityComaprer with a call to the Except Linq method and I'd like to maintain a single source for equality comparisons)

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  • Is opening too many datacontexts bad?

    - by ryudice
    I've been checking my application with linq 2 sql profiler, and I noticed that it opens a lot of datacontexts, most of them are opened by the linq datasource I used, since my repositories use only the instance stored in Request.Items, is it bad to open too many datacontext? and how can I make my linqdatasource to use the datacontext that I store in Request.Items for the duration of the request? thanks for any help!

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