Search Results

Search found 16050 results on 642 pages for 'linq to objects'.

Page 22/642 | < Previous Page | 18 19 20 21 22 23 24 25 26 27 28 29  | Next Page >

• Combining Variable Numbers of Lists w/ LINQ

  - by Anthony Compton

  I have a list (List) of objects. Each of those objects contains a list (List) of strings describing them. I'm needing to create a dropdown containing all of the distinct strings used to describe the objects (Cards). To do this, I need a list of distinct strings used. Any idea how/if this can be done with LINQ?

  Read the article

• Business Objects and Microsoft Office

  - by michael

  Can Business Objects Enterprise and microsoft office (Excel) Coexist on the same server and work together

  Read the article

• Rails: Serializing objects in a database?

  - by keruilin

  I'm looking for some general guidance on serializing objects in a database. What are serialized objects? What are some best-practice scenarios for serializing objects in a DB? What attributes do you use when creating the column in the DB so you can use a serialized object? How to save a serialized object? And how to access the serialized object and its attributes? (Using hashes?)

  Read the article

• ASP.NET MVC 2: Updating a Linq-To-Sql Entity with an EntitySet

  - by Simon

  I have a Linq to Sql Entity which has an EntitySet. In my View I display the Entity with it's properties plus an editable list for the child entites. The user can dynamically add and delete those child entities. The DefaultModelBinder works fine so far, it correctly binds the child entites. Now my problem is that I just can't get Linq To Sql to delete the deleted child entities, it will happily add new ones but not delete the deleted ones. I have enabled cascade deleting in the foreign key relationship, and the Linq To Sql designer added the "DeleteOnNull=true" attribute to the foreign key relationships. If I manually delete a child entity like this: myObject.Childs.Remove(child); context.SubmitChanges(); This will delete the child record from the DB. But I can't get it to work for a model binded object. I tried the following: // this does nothing public ActionResult Update(int id, MyObject obj) // obj now has 4 child entities { var obj2 = _repository.GetObj(id); // obj2 has 6 child entities if(TryUpdateModel(obj2)) //it sucessfully updates obj2 and its childs { _repository.SubmitChanges(); // nothing happens, records stay in DB } else ..... return RedirectToAction("List"); } and this throws an InvalidOperationException, I have a german OS so I'm not exactly sure what the error message is in english, but it says something along the lines of that the entity needs a Version (Timestamp row?) or no update check policies. I have set UpdateCheck="Never" to every column except the primary key column. public ActionResult Update(MyObject obj) { _repository.MyObjectTable.Attach(obj, true); _repository.SubmitChanges(); // never gets here, exception at attach } I've read alot about similar "problems" with Linq To Sql, but it seems most of those "problems" are actually by design. So am I right in my assumption that this doesn't work like I expect it to work? Do I really have to manually iterate through the child entities and delete, update and insert them manually? For such a simple object this may work, but I plan to create more complex objects with nested EntitySets and so on. This is just a test to see what works and what not. So far I'm disappointed with Linq To Sql (maybe I just don't get it). Would be the Entity Framework or NHibernate a better choice for this scenario? Or would I run into the same problem?

  Read the article

• Proper way to use Linq with WPF

  - by Ingó Vals

  I'm looking for a good guide into the right method of using Linq to Sql together with WPF. Most guides only go into the bare basics like how to show data from a database but noone I found goes into how to save back to the database. Can you answer or point out to me a guide that can answer these questions. I have a separate Data project because the same data will also be used in a web page so I have the repository method. That means I have a seperate class that uses the DataContext and there are methods like GetAllCompanies() and GetCompanyById ( int id ). 1) Where there are collections is it best to return as a IQueryable or should I return a list? Inside the WPF project I have seen reccomendations to wrap the collection in a ObservabgleCollection. 2) Why should I use ObservableCollection and should I use it even with Linq / IQueryable Some properties of the linq entities should be editable in the app so I set them to two-way mode. That would change the object in the observableCollection. 3) Is the object in the ObservableCollection still a instance of the original linq entity and so is the change reflected in the database ( when submitchanges is called ) I should have somekind of save method in the repository. But when should I call it? What happens if someone edits a field but decides not to save it, goes to another object and edits it and then press save. Doesn't the original change also save? When does it not remember the changes to a linq entity object anymore. Should I instance the Datacontext class in each method so it loses scope when done. 4) When and how to call the SubmitChanges method 5) Should I have the DataContext as a member variable of the repository class or a method variable To add a new row I should create a new object in a event ( "new" button push ) and then add it to the database using a repo method. 6) When I add the object to the database there will be no new object in the ObservableCollection. Do I refresh somehow. 7) I wan't to reuse the edit window when creating new but not sure how to dynamically changing from referencing selected item from a listview to this new object. Any examples you can point out.

  Read the article

• Are elements returned by Linq-to-Entities query streamed from the DB one at the time or are they retrieved all at once?

  - by carewithl

  Are elements returned by Linq-to-Entities query streamed from the database one at the time ( as they are requested ) or are they retrieved all at once: SampleContext context = new SampleContext(); // SampleContext derives from ObjectContext var search = context.Contacts; foreach (var contact in search) { Console.WriteLine(contact.ContactID); // is each Contact retrieved from the DB // only when foreach requests it? } thank you in advance

  Read the article

• LinqToSQL _conn ? LinqToSQLConnection ?

  - by nCdy

  here is a code : using System; using Nemerle.Collections; using Nemerle.Text; //using Nemerle.Utility; using System.Linq; using Nemerle.Data.Linq; using NUnit.Framework; using System.Data.Linq; namespace LinqTestes { [TestFixture] public class Linq2SqlTests { static ReadConnectionString() : string { def currAssm = Uri(typeof(Linq2SqlTests).Assembly.CodeBase).LocalPath; def path = IO.Path.GetDirectoryName(currAssm); def connStrPath = IO.Path.Combine(path, "connectionString.txt"); def connStr = try { IO.File.ReadAllText(connStrPath, Text.Encoding.UTF8) } catch { | e is IO.FileNotFoundException => throw IO.FileNotFoundException( $"You should define connection string to NorthWind DB in: '$connStrPath'", e.FileName, e) }; connStr } _conn : LinqDataConnection = LinqDataConnection(ReadConnectionString()); and I'm making the same but what is LinqDataConnection type ? and where does it comes from ?

  Read the article

• C# Dynamic Query Without A Database Model

  - by hitopp

  I have been searching the web for a solution to dynamic queries. I have found many different solutions (e.g. Linq to Sql, Dynamic Linq Expressions, Dynamic Query), but all of these solutions involve some sort of previous knowledge of the database (like a model in code). Maybe what I am asking is way off the deep end, but is there any possible way to dynamically query a database without a model? For example, a database has a Customers table with the following columns: CustomerID Name FavoriteColor I want to create a query as SELECT Name FROM Customers WHERE @0 = @1, where the two placeholders are populated dynamically. The resulting data does not tie to a model class and I would prefer to use some sort of framework to build the queries, not simple string concatenation. The System.Linq.Dynamic namespace came really close to fulfilling this request, but it uses a database model. I realize this is crazy, but I was just curious.

  Read the article

• How to Link VS2010 Database Project and LINQ to SQL

  - by Jason

  As I am working with the new database projects in VS2010, and as I am learning LINQ to SQL, I am curious as to the best way to link the two groups of information so that when I update one, the other updates along with it. From my research here at SO, as well as in Google, it appears the general rule of thumb is: "Build the database, and then create your LINQ to SQL classes." Of course, if I make a change in my database, the LINQ to SQL doesn't update automatically and I have to do it by hand. This is fairly simple right now as my database is small, but I am curious if there is an easier way for this to happen. In addition, the LINQ to SQL tool is pretty nice. The ability to create tables, add associations, and even create inheritance is very simple. As my second question, I am curious as to whether or not VS2010 can work the other way - I design the database in the DBLM file and then link it back to my database project. I appreciate any help with either of these two questions. I'm really interested in making this as easy as possible to reduce errors during development and improve the speed at which changes can be made.

  Read the article

• Selecting a multi-dimensional array in LINQ

  - by mckhendry

  I have a task where I need to translate a DataTable to a two-dimensional array. That's easy enough to do by just looping over the rows and columns (see example below). private static string[,] ToArray(DataTable table) { var array = new string[table.Rows.Count,table.Columns.Count]; for (int i = 0; i < table.Rows.Count; ++i) for (int j = 0; j < table.Columns.Count; ++j) array[i, j] = table.Rows[i][j].ToString(); return array; } What I'd really like to do is use a select statement in LINQ to generate that 2D array. Unfortunately it looks like there is no way in LINQ to select a multidimensional array. Yes, I'm aware that I can use LINQ to select a jagged array, but that's not what I want. Is my assumption correct, or is there a way to use LINQ to select a multi-dimensional array?

  Read the article

• Merging sequences by type With LINQ

  - by jankor

  I want to use LINQ to convert this IEnumerable<int>[] value1ByType = new IEnumerable<int>[3]; value1ByType[0]= new [] { 0}; value1ByType[1]= new [] {10,11}; value1ByType[2]= new [] {20}; var value2ToType = new Dictionary<int,int> { {100,0}, {101,1}, {102,2}, {103,1}}; to this var value2ToValue1 = new Dictionary<int,int> { {100, 0}, {101,10}, {102,20}, {103,11}}; Is there a way to do this with LINQ? Without LINQ I would use multiple IEnumerators, one for each IEnumerable of value1ByType. like this: // create enumerators var value1TypeEnumerators = new List<IEnumerator<int>>(); for (int i = 0; i < value1ByType.Length; i++) { value1TypeEnumerators.Add(value1ByType[i].GetEnumerator()); value1TypeEnumerators[i].MoveNext(); } // create wanted dictionary var value2ToValue1 = new Dictionary<int, int>(); foreach (var item in Value2ToType) { int value1=value1TypeEnumerators[item.Value].Current; value2ToValue1.Add(item.Key, value1); value1TypeEnumerators[item.Value].MoveNext(); } Any Idea how to do this in LINQ?

  Read the article

• LINQ Query please help C#.Net.

  - by Paul Matthews

  I'm very new to LINQ and struggling to find the answers. I have a simple SQL query. Select ID, COUNT(ID) as Selections, OptionName, SUM(Units) as Units FROM tbl_Results GROUP BY ID, OptionName. The results I got were: '1' '4' 'Approved' '40' '2' '1' 'Rejected' '19' '3' '2' 'Not Decided' '12' Due to having to encrypt all my data in the database I'm unable to do sums. Therefore I have now brought back the data and decrypt it in the application layer. Results would be: '1' 'Approved' '10' '3' 'Not Deceided' '6' '2' 'Rejected' '19' '1' 'Approved' '15' '1' 'Approved' '5' '3' 'Not Deceided' '6' '1' 'Approved' '10' using a simple class I have called back the above results, and put them in a list class. public class results { public int ID {get;set;} public string OptionName {get;set;} public int Unit {get;set;} } I almost have the LINQ query to bring back the results like the SQL query at the top var q = from r in Results group p.Unit by p.ID int g select new {ID = g.Key, Selections = g.Count(), Units = g.Sum()}; How do I ensure my LINQ query also give me the Option Name? Also if I created a class called Statistics to hold my results how would I modify the LINQ query to give me list result set? public class results { public int ID {get;set;} public int NumberOfSelections { get; set; } public string OptionName {get;set;} public int UnitTotal {get;set;} }

  Read the article

• Show me your Linq to SQL architectures!

  - by Brad Heller

  I've been using Linq to SQL for a new implementation that I've been working on. I have about 5000 lines of code and am a little ways from a solid demo. I've been pretty satisfied with Linq to SQL so far -- the tools are excellent and pretty painless and it allows you to get a DAL up and running quickly. That said, there are some major draw backs that I just keep hitting over and over again. Namely how to handle separation of concerns between my DAL and my business layer and juggling that with different data contexts. Here is the architecture I've been using: My repositories do all my data access and they return Linq to SQL objects. Each of my Linq to SQL objects implements an IDetachable interface. A typical implementation looks like this: partial class PaymentDetail : IDetachable { #region IDetachable Members public bool IsAttached { get { return PropertyChanging != null; } } public void Detach() { if (IsAttached) { PropertyChanged = null; PropertyChanging = null; Transaction.Detach(); } } #endregion } Every time I do a DAL operation in my repository I "detach" when I'm done with the object (and it should theoretically detach from any child objects) to remove the DataContext's context. Like I said, this works pretty well, but there are some edge cases that seem to be a big pain in the ass. For instance, my Transaction object has many PaymentDetails. Even when there are no PaymentDetails in that collection it's still attached to the DataContext's context! Thus, if I try to update (I update by Attach()ing to the object and then SubmitChanges()) I get that dreaded "An attempt has been made to Attach or Add an entity that is not new, perhaps having been loaded from another DataContext. This is not supported." message. Anyway, I'm starting to doubt that this technology was a good gamble. Has anyone got a decent architecture that they're willing to share? I'd really love to use this technology but I feel like I spend 1/3 of my time just debugging is retarded quirks!

  Read the article

• VB.NET switching from ADO.NET to LINQ

  - by Cj Anderson

  I'm VERY new to Linq. I have an application I wrote that is in VB.NET 2.0. Works great, but I'd like to switch this application to Linq. I use ADO.NET to load XML into a datatable. The XML file has about 90,000 records in it. I then use the Datatable.Select to perform searches against that Datatable. The search control is a free form textbox. So if the user types in terms it searches instantly. Any further terms that are typed in continue to restrict the results. So you can type in Bob, or type in Bob Barker. Or type in Bob Barker Price is Right. The more criteria typed in the more narrowed your result. I bind the results to a gridview. Moving forward what all do I need to do? From a high level, I assume I need to: 1) Go to Project Properties -- Advanced Compiler Settings and change the Target framework to 3.5 from 2.0. 2) Add the reference to System.XML.Linq, Add the Imports statement to the classes. So I'm not sure what the best approach is going forward after that. I assume I use XDocument.Load, then my search subroutine runs against the XDocument. Do I just do the standard Linq query for this sort of repeated search? Like so: var people = from phonebook in doc.Root.Elements("phonebook") where phonebook.Element("userid") = "whatever" select phonebook; Any tips on how to best implement?

  Read the article

• Alternatives to LINQ To SQL on high loaded pages

  - by Alex

  To begin with, I LOVE LINQ TO SQL. It's so much easier to use than direct querying. But, there's one great problem: it doesn't work well on high loaded requests. I have some actions in my ASP.NET MVC project, that are called hundreds times every minute. I used to have LINQ to SQL there, but since the amount of requests is gigantic, LINQ TO SQL almost always returned "Row not found or changed" or "X of X updates failed". And it's understandable. For instance, I have to increase some value by one with every request. var stat = DB.Stats.First(); stat.Visits++; // .... DB.SubmitChanges(); But while ASP.NET was working on those //... instructions, the stats.Visits value stored in the table got changed. I found a solution, I created a stored procedure UPDATE Stats SET Visits=Visits+1 It works well. Unfortunately now I'm getting more and more moments like that. And it sucks to create stored procedures for all cases. So my question is, how to solve this problem? Are there any alternatives that can work here? I hear that Stackoverflow works with LINQ to SQL. And it's more loaded than my site.

  Read the article

• LINQ Joins - Performance

  - by Meiscooldude

  I am curious on how exactly LINQ (not LINQ to SQL) is performing is joins behind the scenes in relation to how Sql Server performs joins. Sql Server before executing a query, generates an Execution Plan. The Execution Plan is basically an Expression Tree on what it believes is the best way to execute the query. Each node provides information on whether to do a Sort, Scan, Select, Join, ect. On a 'Join' node in our execution plan, we can see three possible algorithms; Hash Join, Merge Join, and Nested Loops Join. Sql Server will choose which algorithm to for each Join operation based on expected number of rows in Inner and Outer tables, what type of join we are doing (some algorithms don't support all types of joins), whether we need data ordered, and probably many other factors. Join Algorithms: Nested Loop Join: Best for small inputs, can be optimized with ordered inner table. Merge Join: Best for medium to large inputs sorted inputs, or an output that needs to be ordered. Hash Join: Best for medium to large inputs, can be parallelized to scale linearly. LINQ Query: DataTable firstTable, secondTable; ... var rows = from firstRow in firstTable.AsEnumerable () join secondRow in secondTable.AsEnumerable () on firstRow.Field<object> (randomObject.Property) equals secondRow.Field<object> (randomObject.Property) select new {firstRow, secondRow}; SQL Query: SELECT * FROM firstTable fT INNER JOIN secondTable sT ON fT.Property = sT.Property Sql Server might use a Nested Loop Join if it knows there are a small number of rows from each table, a merge join if it knows one of the tables has an index, and Hash join if it knows there are a lot of rows on either table and neither has an index. Does Linq choose its algorithm for joins? or does it always use one?

  Read the article

• Problem with LINQ query

  - by Niels Bosma

  The following works fine: (from e in db.EnquiryAreas from w in db.WorkTypes where w.HumanId != null && w.SeoPriority > 0 && e.HumanId != null && e.SeoPriority > 0 && db.Enquiries.Where(f => f.WhereId == e.Id && f.WhatId == w.Id && f.EnquiryPublished != null && f.StatusId != EnquiryMethods.STATUS_INACTIVE && f.StatusId != EnquiryMethods.STATUS_REMOVED && f.StatusId != EnquiryMethods.STATUS_REJECTED && f.StatusId != EnquiryMethods.STATUS_ATTEND ).Any() select new { EnquiryArea = e, WorkType = w }); But: (from e in db.EnquiryAreas from w in db.WorkTypes where w.HumanId != null && w.SeoPriority > 0 && e.HumanId != null && e.SeoPriority > 0 && EnquiryMethods.BlockOnSite(db.Enquiries.Where(f => f.WhereId == e.Id && f.WhatId == w.Id)).Any() select new { EnquiryArea = e, WorkType = w }); + public static IQueryable<Enquiry> BlockOnSite(IQueryable<Enquiry> linq) { return linq.Where(e => e.EnquiryPublished != null && e.StatusId != STATUS_INACTIVE && e.StatusId != STATUS_REMOVED && e.StatusId != STATUS_REJECTED && e.StatusId != STATUS_ATTEND ); } I get the following error: base {System.SystemException}: {"Method 'System.Linq.IQueryable1[X.Enquiry] BlockOnSite(System.Linq.IQueryable1[X.Enquiry])' has no supported translation to SQL."}

  Read the article

• Advice on Linq to SQL mapping object design

  - by fearofawhackplanet

  I hope the title and following text are clear, I'm not very familiar with the correct terms so please correct me if I get anything wrong. I'm using Linq ORM for the first time and am wondering how to address the following. Say I have two DB tables: User ---- Id Name Phone ----- Id UserId Model The Linq code generator produces a bunch of entity classes. I then write my own classes and interfaces which wrap these Linq classes: class DatabaseUser : IUser { public DatabaseUser(User user) { _user = user; } public Guid Id { get { return _user.Id; } } ... etc } so far so good. Now it's easy enough to find a users phones from Phones.Where(p => p.User = user) but surely comsumers of the API shouldn't need to be writing their own Linq queries to get at data, so I should wrap this query in a function or property somewhere. So the question is, in this example, would you add a Phones property to IUser or not? In other words, should my interface specifically be modelling my database objects (in which case Phones doesn't belong in IUser), or are they actually simply providing a set of functions and properties which are conceptually associated with a User (in which case it does)? There seems drawbacks to both views, but I'm wondering if there is a standard approach to the problem. Or just any general words of wisdom you could share. My first thought was to use extension methods but in fact that doesn't work in this case.

  Read the article

• Complex Javascript objects to JSON Objects

  - by cooldude

  Hi, Is there is any Javascript API that converts complex Javascript Objects To JSON Objects???

  Read the article

• LINQ to Entities for subtracting 2 dates

  - by Michael I

  I am trying to determine the number of days between 2 dates using LINQ with Entity Framework. It is telling me that it does not recognize Subtract on the System.TimeSpan class Here is my where portion of the LINQ query. where ((DateTime.Now.Subtract(vid.CreatedDate).TotalDays < maxAgeInDays)) Here is the error I receive in the VS.NET debugger {"LINQ to Entities does not recognize the method 'System.TimeSpan Subtract(System.DateTime)' method, and this method cannot be translated into a store expression."} Am I doing something wrong or is there a better way to get the number of days between 2 DateTimes in the entity framework? thanks Michael

  Read the article

• C# LINQ Oracle date Functions

  - by user1079925

  I am trying to generate a sql statement to be used in Oracle11g, using linq. The problem arises when using dates: The SQL generated by linq gives SELECT * FROM <table> WHERE start_date > '24/11/2012 00:00:00' and end_date < '28/11/2012 00:00:00' This causes an oracle error: ORA-01830 - date format picture ends before converting entire input string Adding TO_DATE to the query fixes the ORA-01830, as it is converting the string to a oracle date whilst now knowing the date format. SELECT * FROM <table> WHERE start_date > TO_DATE('24/11/2012 00:00:00','DD/MM/YYYY HH24:MI:SS') and end_date < TO_DATE('28/11/2012 00:00:00','DD/MM/YYYY HH24:MI:SS') So, is there a way to add TO_DATE to LINQ (for oracle)? If not, please tell me how to work around this issue. Thanks

  Read the article

• What is the leading LINQ for JavaScript library?

  - by Tom Tresansky

  I'm looking for a JavaScript library that will allow me to query complex JSON objects using a LINQ-like syntax. A quick search found a couple of promising options that look they might offer what I need: LINQ to JavaScript and jLinq Does any one have any experience using them? What are some pros and cons? Is the performance comparable? Does the function-passing syntax of LINQ to JavaScript offer any hidden benefits (I personally find the syntax of jLinq more appealing on first glance)? What have you found lacking in either project? Did you ever try contacting the authors? How responsive were they? What project is more widely used?

  Read the article

• Defaultifempty seems to work in linq to entities

  - by Rand

  I'm new to linq and linq to entities so I might have gone wrong in my assumptions, but I've been unknowingly trying to use DefaultIfEmpty in L2E. For some reason if I turn the resultset into a List, the Defaultifempty() works I don't know if I've inadvertantly crossed over into Linq area. The code below works, can anyone tell me why? And if it does work great, then it'll be of help to other people. var results = (from u in rv.tbl_user .Include("tbl_pics") .Include("tbl_area") .Include("tbl_province") .ToList() where u.tbl_province.idtbl_Province == prov select new { u.firstName, u.cellNumber, u.tbl_area.Area, u.ID,u.tbl_province.Province_desc, pic = (from p3 in u.tbl_pics where p3.tbl_user.ID == u.ID select p3.pic_path).DefaultIfEmpty("defaultpic.jpg").First() }).ToList();

  Read the article

• LLBLGEN: Linq to LLBGEN don't work

  - by StreamT

  I want to make custom select from the database table using Linq. We use LLBGEN as ORM solution. I can't do LINQ query to Entities Collection Class unless I call GetMulti(null) method of it. Is it possible to do LINQ query to LLBGEN without extracting all table first? BatchCollection batches = new BatchCollection(); BatchEntity batch = batches.AsQueryable() .Where(i => i.RegisterID == 3) .FirstOrDefault(); // Exception: Sequence don't contains any elements batches = new BatchCollection(); batches.GetMulti(null); // I don't want to extract the whole table. BatchEntity batch = batches.AsQueryable() .Where(i => i.RegisterID == 3) .FirstOrDefault(); //Works fine

  Read the article

• Teaching coworkers LINQ...

  - by cyberzed

  I have set myself upon a journey to educate my coworkers (all have accepted my mission, even the boss). Every day I seem to find a piece of code that could have been less error prone if my coworkers knew more about the framework, better-know-framework (in courtesy of DNR ;)) is part two of my teaching process. First part is teaching my coworkers about LINQ, what it can do for them and how it is written. My big question is where are all the good basic resources for LINQ education, everything if find is tightly coupled to Linq2Sql or all other sorts of material. Neither have I been able to find a tutorial for the actual linq syntax (except a specification of it all). (I hope this haven't been asked before but if it has please say so, cause then my searching skills have failed ;) )

  Read the article

< Previous Page | 18 19 20 21 22 23 24 25 26 27 28 29  | Next Page >