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  • LINQ-to-XML selection based on node values, newbie question

    - by mmcglynn
    Given the following XML, I would like to return all eventtitles where the eventtype id = 23. My current query only looks at the first eventtype, so returns the wrong result. <event> <eventtitle>Garrison Keillor</eventtitle> <eventtypes> <eventtype id="24"/> <eventtype id="23"/> </eventtypes> </event> <event> <eventtitle>Joe Krown Trio featuring Walter Wolfman Washington</eventtitle> <eventtypes> <eventtype id="23"/> </eventtypes> </event> LINQ query: Dim query = _ From c In calXML...<event> _ Where c...<eventtypes>.<eventtype>.@id = "23" _ Select c.<eventtitle>.Value, c.<eventlocation>.Value For Each item In query Response.Write("<h3>" & item.eventtitle & "</h3>") Response.Write(item.eventlocation & "<br />") Next

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  • Delete record in Linq to Sql

    - by Anders Svensson
    I have Linq2Sql classes User, Page, and UserPage (from a junction table), i.e. a many-to-many relationship. I'm using a gridview to show all Users, with a dropdownlist in each row to show the Pages visited by each user. Now I want to be able to delete records through the gridview, so I have added a delete button in the gridview by setting "Enable deleting" on it. Then I tried to use the RowDeleting event to specify how to delete the records since it doesn't work by default. And because its a relationship I know I need to delete the related records in the junction table before deleting the user record itself, so I added this in the RowDeleting event: protected void GridView2_RowDeleting(object sender, GridViewDeleteEventArgs e) { int id = (int)((DataKey)GridView2.DataKeys[e.RowIndex]).Value; UserPageDBDataContext context = new UserPageDBDataContext(); var userPages = from userPage in context.UserPages where userPage.User.UserID == id select userPage; foreach (var userPage in userPages) context.UserPages.DeleteOnSubmit(userPage); context.SubmitChanges(); var user = context.Users.Single(u => u.UserID == id); context.Users.DeleteOnSubmit(user); context.SubmitChanges(); } This actually seems to delete records, because the record with the id in question does indeed disappear, but strangely, a new record seems to be added at the end...! So, say I have 3 records in the gridview: 1 Jack stackoverflow.com 2 Betty stackoverflow.com/questions 3 Joe stackoverflow.com/whatever Now, if I try to delete user 1 (Jack), record number 1 will indeed disappear in the gridview, but the same record will appear at the end with a new id: 2 Jack stackoverflow.com 3 Betty stackoverflow.com/questions 4 Joe stackoverflow.com/whatever I have tried searching on how to delete records using Linq, and I believe I'm doing exacly as the examples I have read (e.g. the second example here: http://msdn.microsoft.com/en-us/library/Bb386925%28v=VS.100%29.aspx). I have read that you can also set cascade delete on the relationship in the database, but I wanted to do it this way in code, as your supposed to be able to. So what am I doing wrong?

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  • Dynamic where clause using Linq to SQL in a join query in a MVC application

    - by jhoefnagels
    Dear .Net Linq experts, I am looking for a way to query for products in a catalog using filters on properties which have been assigned to the product based on the category to which the product belongs. So I have the following entities involved: Products -Id -CategoryId Categories [Id] Properties [Id, CategoryId] PropertyValues [Id, PropertyId] ProductProperties [ProductId, PropertyValueId] When I ad a product to the catalog, multiple ProductProperties will be added based on the category and I would like to be able to filter all products from a category by selecting values for one or more properties. I will gather all filters, which I will hold in a list, by reading the URL. Now it is time to actually get the products based on multiple properties and I have been trying to find the right strategy but untill now it does not really work. Is there a way to make this work without writing SQL? I was trying something like this: productsInCategory = ProductRepository.Where(p => p.Category.Name == category); foreach (PropertyFilter pf in filterList) { productsInCategory = (from product in productsInCategory join pp in ProductPropertyRepository on product.Id equals pp.ProductId where pp.PropertyValueId == pf.ValueId select product); }

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  • Linq Query to Update Nested Array Items?

    - by Brett
    I have an object structure generated from xsd.exe. Roughly, it consists of 3 nested arrays: protocols, sources and reports. The xml looks like this: <protocols> <protocol> <source> <report /> <report /> </source> <source> <report /> <report /> </source> </protocol> <!-- more protocols --> </protocols> I need to update a single "Report" within the data structure. A brute force algorithm is shown below. I know that this could be done using XDocument and Linq, but I'd prefer to update the data structure and then serialize the structure back to disk. Thoughts? Brett bool updated = false; foreach (ProtocolsProtocol protocol in protocols.Protocol) { if (updated) break; foreach (ProtocolsProtocolSource source in protocol.Source) { if (updated) break; for (int i = 0; i < source.Report.Length; i++) { ProtocolsProtocolSourceReport currentReport = source.Report[i]; if (currentReport.Id == report.Id) { currentReport.Attribute1 = report.Attribute1; currentReport.Attribute2 = report.Attribute2; updated = true; break; } } } }

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  • Linq to XML: create an anonymous object with element attributes and values

    - by Phil Scholtes
    I'm new to Linq and I'm trying to query a XML document to find a list of account managers for a particular user. (I realize it might make more sense to put this in a database or something else, but this scenario calls for a XML document). <user emailAddress='[email protected]'> <accountManager department='Customer Service' title='Manager'>[email protected]</accountManager> <accountManager department='Sales' title='Account Manager'>[email protected]</accountManager> <accountManager department='Sales' title='Account Manager'>[email protected]</accountManager> </user> I trying to create a list of objects (anonymous type?) with properties consisting of both XElement attributes (department, title) and values (email). I know that I can get either of the two, but my problem is selecting both. Here is what I'm trying: var managers = _xDoc.Root.Descendants("user") .Where(d => d.Attribute("emailAddress").Value == "[email protected]") .SelectMany(u => u.Descendants("accountManager").Select(a => a.Value)); foreach (var manager in managers) { //do stuff } I can get at a.Value and a.Attribute but I can't figure out how to get both and store them in an object. I have a feeling it would wind up looking something like: select new { department = u.Attribute("department").Value, title = u.Attribute("title").Value, email = u.Value };

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  • C# - Help with LINQ

    - by cmaduro
    I need to check if a certain property exists within a class. Please refer to the LINQ query in question. For the life of me I cannot make the compiler happy. class Program { static void Main(string[] args) { ModuleManager m = new ModuleManager(); IModule module = m.FindModuleForView(typeof(HomeView)); Console.WriteLine(module.GetType().ToString()); Console.ReadLine(); } } public class ModuleManager { [ImportMany] public IEnumerable<Lazy<IModule>> Modules { get; set; } [ImportMany] public IEnumerable<Lazy<View>> Views { get; set; } public ModuleManager() { //An aggregate catalog that combines multiple catalogs var catalog = new AggregateCatalog(); //Adds all the parts found in the same assembly as the Program class catalog.Catalogs.Add(new AssemblyCatalog(typeof(Program).Assembly)); //Create the CompositionContainer with the parts in the catalog _container = new CompositionContainer(catalog); //Fill the imports of this object try { this._container.ComposeParts(this); } catch (CompositionException compositionException) { Console.WriteLine(compositionException.ToString()); } } public IModule FindModuleForView(Type view) { //THIS IS THE PROBLEM var module = from m in Modules where ( from p in m.Value.GetType().GetProperties() where p.GetType().Equals(view) select p ) select m; } public CompositionContainer _container { get; set; } } public interface IModule { } [Export] public class HomeModule : IModule { public HomeModule() { } [Export] public HomeView MyHomeView { get { return new HomeView(); } set { } } } public class HomeView : View { } public class View { }

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  • Passing a LINQ DataRow Reference in a GridView's ItemTemplate

    - by Bob Kaufman
    Given the following GridView: <asp:GridView runat="server" ID="GridView1" AutoGenerateColumns="false" DataKeyNames="UniqueID" OnSelectedIndexChanging="GridView1_SelectedIndexChanging" > <Columns> <asp:BoundField HeaderText="Remarks" DataField="Remarks" /> <asp:TemplateField HeaderText="Listing"> <ItemTemplate> <%# ShowListingTitle( ( ( System.Data.DataRowView ) ( Container.DataItem ) ).Row ) %> </ItemTemplate> </asp:TemplateField> <asp:BoundField HeaderText="Amount" DataField="Amount" DataFormatString="{0:C}" /> </Columns> </asp:GridView> which refers to the following code-behind method: protected String ShowListingTitle( DataRow row ) { Listing listing = ( Listing ) row; return NicelyFormattedString( listing.field1, listing.field2, ... ); } The cast from DataRow to Listing is failing (cannot convert from DataRow to Listing) I'm certain the problem lies in what I'm passing from within the ItemTemplate, which is simply not the right reference to the current record from the LINQ to SQL data set that I've created, which looks like this: private void PopulateGrid() { using ( MyDataContext context = new MyDataContext() ) { IQueryable < Listing > listings = from l in context.Listings where l.AccountID == myAccountID select l; GridView1.DataSource = listings; GridView1.DataBind(); } }

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  • Linq to SQL with INSTEAD OF Trigger and an Identity Column

    - by Bob Horn
    I need to use the clock on my SQL Server to write a time to one of my tables, so I thought I'd just use GETDATE(). The problem is that I'm getting an error because of my INSTEAD OF trigger. Is there a way to set one column to GETDATE() when another column is an identity column? This is the Linq-to-SQL: internal void LogProcessPoint(WorkflowCreated workflowCreated, int processCode) { ProcessLoggingRecord processLoggingRecord = new ProcessLoggingRecord() { ProcessCode = processCode, SubId = workflowCreated.SubId, EventTime = DateTime.Now // I don't care what this is. SQL Server will use GETDATE() instead. }; this.Database.Add<ProcessLoggingRecord>(processLoggingRecord); } This is the table. EventTime is what I want to have as GETDATE(). I don't want the column to be null. And here is the trigger: ALTER TRIGGER [Master].[ProcessLoggingEventTimeTrigger] ON [Master].[ProcessLogging] INSTEAD OF INSERT AS BEGIN SET NOCOUNT ON; SET IDENTITY_INSERT [Master].[ProcessLogging] ON; INSERT INTO ProcessLogging (ProcessLoggingId, ProcessCode, SubId, EventTime, LastModifiedUser) SELECT ProcessLoggingId, ProcessCode, SubId, GETDATE(), LastModifiedUser FROM inserted SET IDENTITY_INSERT [Master].[ProcessLogging] OFF; END Without getting into all of the variations I've tried, this last attempt produces this error: InvalidOperationException Member AutoSync failure. For members to be AutoSynced after insert, the type must either have an auto-generated identity, or a key that is not modified by the database after insert. I could remove EventTime from my entity, but I don't want to do that. If it was gone though, then it would be NULL during the INSERT and GETDATE() would be used. Is there a way that I can simply use GETDATE() on the EventTime column for INSERTs? Note: I do not want to use C#'s DateTime.Now for two reasons: 1. One of these inserts is generated by SQL Server itself (from another stored procedure) 2. Times can be different on different machines, and I'd like to know exactly how fast my processes are happening.

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  • Using LINQ in generic collections

    - by Hugo S Ferreira
    Hi, Please consider the following snippet from an implementation of the Interpreter pattern: public override object Execute(Interpreter interpreter, object ctx) { var list = ctx as IEnumerable<string>; return (list != null) ? list.FirstOrDefault() : null; } What about if I want to use the same function for integers? public override object Execute(Interpreter interpreter, object ctx) { var list = ctx as IEnumerable<string>; if (list != null) return list.FirstOrDefault(); var list = ctx as IEnumerable<int>; return (list != null) ? list.FirstOrDefault() : null; } What I wanted was something like: public override object Execute(Interpreter interpreter, object ctx) { var list = ctx as IEnumerable; return (list != null) ? list.FirstOrDefault() : null; } But Linq doesn't act on IEnumerables. Instead, to get to this solution, I would be forced to write something like: public override object Execute(Interpreter interpreter, object ctx) { var list = ctx as IEnumerable; if (list != null) foreach(var i in list) { yield return i; return; } return null; } Or use a generic method: public override T Execute<T>(Interpreter interpreter, object ctx) { var list = ctx as IEnumerable<T>; return (list != null) ? list.FirstOrDefault() : null; } Which would break the Interpreter pattern (as it was implemented in this system). Covariance would also fail (at least in C#3), though would it work, it would be the exact behavior I wanted: public override object Execute(Interpreter interpreter, object ctx) { var list = ctx as IEnumerable<object>; return (list != null) ? list.FirstOrDefault() : null; } So, my question is: what's the best way to achieve the intended behavior? Thanks :-)

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  • LINQ-To-SQL and Mapping Table Deletions

    - by Jake
    I have a many-to-many relationship between two tables, let's say Friends and Foods. If a friend likes a food I stick a row into the FriendsFoods table, like this: ID Friend Food 1 'Tom' 'Pizza' FriendsFoods has a Primary Key 'ID', and two non-null foreign keys 'Friend' and 'Food' to the 'Friends' and 'Foods' tables, respectively. Now suppose I have a Friend tom .NET object corresponding to 'Tom', and Tom no longer likes pizza (what is wrong with him?) FriendsFoods ff = tblFriendsFoods.Where(x => x.Friend.Name == 'Tom' && x.Food.Name == 'Pizza').Single(); tom.FriendsFoods.Remove(ff); pizza.FriendsFoods.Remove(ff); If I try to SubmitChanges() on the DataContext, I get an exception because it attempts to insert a null into the Friend and Food columns in the FriendsFoods table. I'm sure I can put together some kind of convoluted logic to track changes to the FriendsFoods table, intercept SubmitChanges() calls, etc to try and get this to work the way I want, but is there a nice, clean way to remove a Many-To-Many relationship with LINQ-To-SQL?

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  • Linq to XML Document Traversal

    - by Perpetualcoder
    I have an xml document like this: <?xml version="1.0" encoding="utf-8" ?> <demographics> <country id="1" value="USA"> <state id ="1" value="California"> <city>Long Beach</city> <city>Los Angeles</city> <city>San Diego</city> </state> <state id ="2" value="Arizona"> <city>Tucson</city> <city>Phoenix</city> <city>Tempe</city> </state> </country> <country id="2" value="Mexico"> <state id ="1" value="Baja California"> <city>Tijuana</city> <city>Rosarito</city> </state> </country> </demographics> How do I setup LINQ queries for doing things like: 1. Get All Countries 2. Get All States in a Country 3. Get All Cities inside a state of a paricular country ? I gave it a try and I am kind of confused when to use Elements["NodeName"] and Descendants etc. I know I am not the brightest XML guy around. Is the format of the XML file even correct for simple traversal?

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  • Quering container with Linq + group by ?

    - by Prix
    public class ItemList { public int GuID { get; set; } public int ItemID { get; set; } public string Name { get; set; } public entityType Status { get; set; } public class Waypoint { public int Zone { get; set; } public int SubID { get; set; } public int Heading { get; set; } public float PosX { get; set; } public float PosY { get; set; } public float PosZ { get; set; } } public List<Waypoint> Routes = new List<Waypoint>(); } I have a list of items using the above class and now I need to group it by ItemID and join the first entry of Routes of each iqual ItemID. So for example, let's say on my list I have: GUID ItemID ListOfRoutes 1 23 first entry only 2 23 first entry only 3 23 first entry only 4 23 first entry only 5 23 first entry only 6 23 first entry only 7 23 first entry only Means I have to group entries 1 to 7 as 1 Item with all the Routes entries. So I would have one ItemID 23 with 7 Routes on it where those routes are the first element of that given GUID Routes List. My question is if it is possible using LINQ to make a statment to do something like that this: var query = from ItemList entry in myList where status.Contains(entry.Status) group entry by entry.ItemID into result select new { items = new { ID = entry.ItemID, Name = entry.Name }, routes = from ItemList m in entry group m.Routes.FirstOrDefault() by n.NpcID into m2 }; So basicly I would have list of unique IDS information with a inner list of all the first entry of each GUID route that had the same ItemID.

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  • using indexer to retrieve Linq to SQL object from datastore

    - by fearofawhackplanet
    class UserDatastore : IUserDatastore { ... public IUser this[Guid userId] { get { User user = (from u in _dataContext.Users where u.Id == userId select u).FirstOrDefault(); return user; } } ... } One of the developers in our team is arguing that an indexer in the above situation is not appropriate and that a GetUser(Guid id) method should be prefered. The arguments being that: 1) We aren't indexing into an in-memory collection, the indexer is basically performing a hidden SQL query 2) Using a Guid in an indexer is bad (FxCop flagged this also) 3) Returning null from an indexer isn't normal behaviour 4) An API user generally wouldn't expect any of this behaviour I agree to an extent with (most of) these points. But I'm also inclined to argue that one of the characteristics of Linq is to abstract the database access to make it appear that you're simply working with a bunch of collections, even though the lazy evaluation paradigm means those collections aren't evaluated until you run a query over them. It doesn't seem inconsistent to me to access the datastore in the same manner as if it was a concrete in-memory collection here. Also bearing in mind this is an inherited codebase which uses this pattern extensively and consistently, is it worth the refactoring? I accept that it might have been better to use a Get method from the start, but I'm not yet convinced that it's completely incorrect to be using an indexer. I'd be interested to hear all opinions, thanks.

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  • LINQ to SQL and DataPager

    - by Jonathan S.
    I'm using LINQ to SQL to search a fairly large database and am unsure of the best approach to perform paging with a DataPager. I am aware of the Skip() and Take() methods and have those working properly. However, I'm unable to use the count of the results for the datapager, as they will always be the page size as determined in the Take() method. For example: var result = (from c in db.Customers where c.FirstName == "JimBob" select c).Skip(0).Take(10); This query will always return 10 or fewer results, even if there are 1000 JimBobs. As a result, the DataPager will always think there's a single page, and users aren't able to navigate across the entire result set. I've seen one online article where the author just wrote another query to get the total count and called that. Something like: int resultCount = (from c in db.Customers where c.FirstName == "JimBob" select c).Count(); and used that value for the DataPager. But I'd really rather not have to copy and paste every query into a separate call where I want to page the results for obvious reasons. Is there an easier way to do this that can be reused across multiple queries? Thanks.

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  • Error when calling SQL SP via LINQ

    - by PaulC
    Newbie problem: I have a SQL SP with ten parameters (eight input, two output) but when I attempt to call it via LINQ from code I get the following error message: "The best overloaded method match for 'DataClassesDataContext.ST_CR_CREATE_CASE_BASIS(string, string, string, string, System.DateTime?, string, string, string, ref int?, ref int?)' has some invalid arguments". The params with ? appear to be unrecognized, but I'm baffled: the data types match the SQL types, the number of parameters match, the other parmeters don't exhibit the same behaviour. Can anyone tell me what's going on? Thanks in advance. -- SQL SP: create procedure ST_CR_CREATE_CASE_BASIS @p_Pers_No nvarchar (50), @p_Subject nvarchar (255), @p_RQ_XML nvarchar(max), @p_RQ_XSL nvarchar(max), @p_Date_Submit smalldatetime, @p_User_ID_Submit nvarchar (255), @p_RQ_Status nvarchar (50), @p_User_ID_OnBehalf nvarchar (255), @p_Case_Number int output, @p_RQ_ID int output as begin -- ... etc.; the SP works fine when called from SSMS The code-behind proc from the aspx page looks like this: protected void cmdSubmit_Click(object sender, EventArgs e) { using (DataClassesDataContext vDataCont = new DataClassesDataContext()) { Int32 vNewCaseNr; Int32 vNewReqNr; DateTime vNow = System.DateTime.Now; vDataCont.ST_CR_CREATE_CASE_BASIS("101", "Test Subject Late Wed", null, null, vNow , "101", "1", "101", ref vNewCaseNr, vNewReqNr); } }

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  • Linq Getting Customers group by date and then by their type

    - by Nitin varpe
    I am working on generating report for showing customer using LINQ in C#. I want to show no. of customers of each type. There are 3 types of customer registered, guest and manager. I want to group by customers by registered date and then by type of customer. i.e If today 3 guest, 4 registered and 2 manager are inserted. and tomorrow 4,5 and 6 are registered resp. then report should show Number of customers registerd on the day . separate row for each type. DATE TYPEOF CUSTOMER COUNT 31-10-2013 GUEST 3 31-10-2013 REGISTERED 4 31-10-2013 MANAGER 2 30-10-2013 GUEST 5 30-10-2013 REGISTERED 10 30-10-2013 MANAGER 3 LIKE THIS . var subquery = from eat in _customerRepo.Table group eat by new { yy = eat.CreatedOnUTC.Value.Year, mm = eat.CreatedOnUTC.Value.Month, dd = eat.CreatedOnUTC.Value.Day } into g select new { Id = g.Min(x => x.Id) }; var query = from c in _customerRepo.Table join cin in subquery.Distinct() on c.Id equals cin.Id select c; By above query I get minimum cutomers registerd on that day Thanks in advance

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  • C#/LINQ: How to define generically a keySelector for a templated class before calling OrderBy

    - by PierrOz
    Hi Folks, I have the following class defined in C# class myClass<T,U> { public T PropertyOne { get; set; } public U PropertyTwo { get; set; } } I need to write a function that reorder a list of myClass objects and takes two other parameters which define how I do this reorder: does my reordering depend on PropertyOne or PropertyTwo and is it ascending or descending. Let's say this two parameters are boolean. With my current knowledge in LINQ, I would write: public IList<myClass<T,U>> ReOrder(IList<myClass<T,U>> myList, bool usePropertyOne, bool ascending) { if (usePropertyOne) { if (ascending) { return myList.OrderBy(o => o.PropertyOne).ToList(); } else { return myList.OrderByDescending(o => o.PropertyOne).ToList(); } } else { if (ascending) { return myList.OrderBy(o => o.PropertyTwo).ToList(); } else { return myList.OrderByDescending(o => o.PropertyTwo).ToList(); } } } What could be a more efficient/elegant way to do that ? How can I declare the Func,TResult keySelector object to reuse when I call either OrderBy or OrderByDescending? I'm interesting in the answer since in my real life, I can have more than two properties.

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  • LINQ XML query at c# wp7

    - by Karloss
    I am working at Windows Phone 7 C#, Xaml, XML and LINQ programming. I need to organize search by part of the name at following XML: <Row> <Myday>23</Myday> <Mymonth>12</Mymonth> <Mynames>Alex, Joanna, Jim</Mynames> </Row> <Row> <Myday>24</Myday> <Mymonth>12</Mymonth> <Mynames>John, David</Mynames> </Row> I have following query: var myData = from query in loadedData.Descendants("Row") where query.Element("Mynames").Value.Contains("Jo") select new Kalendars { Myday = (int)query.Element("Myday"), Mymonth = (int)query.Element("Mymonth"), Mynames = (string)query.Element("Mynames") }; listBoxSearch.ItemsSource = myData; Query problem is, that it will return full part of the names like "Alex, Joanna, Jim" and "John, David". How can i get only Joanna and John? Second question is how it is possible to do that user enters ...Value.Contains("jo") and query still returns Joanna and John? Possible solution (needs some corrections) public string Search_names { get { return search_names; } set { string line = this.Mynames; string[] names = line.Split(new[] { ", " }, StringSplitOptions.None); var jos = from name in names where name.Contains("is") select name; // ["Joanna"] // HOW TO BIND search_names? } }

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  • Existing LINQ extension method similar to Parallel.For?

    - by Joel Martinez
    The linq extension methods for ienumerable are very handy ... but not that useful if all you want to do is apply some computation to each item in the enumeration without returning anything. So I was wondering if perhaps I was just missing the right method, or if it truly doesn't exist as I'd rather use a built-in version if it's available ... but I haven't found one :-) I could have sworn there was a .ForEach method somewhere, but I have yet to find it. In the meantime, I did write my own version in case it's useful for anyone else: using System.Collections; using System.Collections.Generic; public delegate void Function<T>(T item); public delegate void Function(object item); public static class EnumerableExtensions { public static void For(this IEnumerable enumerable, Function func) { foreach (object item in enumerable) { func(item); } } public static void For<T>(this IEnumerable<T> enumerable, Function<T> func) { foreach (T item in enumerable) { func(item); } } } usage is: myEnumerable.For<MyClass>(delegate(MyClass item) { item.Count++; });

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  • Running an existing LINQ query against a dynamic object (DataTable like)

    - by TomTom
    Hello, I am working on a generic OData provider to go against a custom data provider that we have here. Thsi is fully dynamic in that I query the data provider for the table it knows. I have a basic storage structure in place so far based on the OData sample code. My problem is: OData supports queries and expects me to hand in an IQueryable implementation. On the lowe rside, I dont have any query support. Not a joke - the provider returns tables and the WHERE clause is not supported. Performance is not an issue here - the tables are small. It is ok to sort them in the OData provider. My main problem is this. I submit a SQL statement to get out the data of a table. The result is some sort of ADO.NET data reader here. I need to expose an IQueryable implementation for this data to potentially allow later filtering. Any ide ahow to best touch that? .NET 3.5 only (no 4.0 planned for some time). I was seriously thinking of creating dynamic DTO classes for every table (emitting bytecode) so I can use standard LINQ. Right now I am using a dictionary per entry (not too efficient) but I see no real way to filter / sort based on them.

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  • How to prevent linq-to-sql designer undo my changing

    - by anonim.developer
    Dear All, Thanks for your attention in advance, I’ve met an issue with LINQ-2-SQL designer in VS 2008 SP1 which has made me CRAZY. I use Linq2sql as my DAL. It seems Linq2sql speeds up coding in the first step but lots of issues arise in feature specifically with table or object inheritance. In this case I have a class Entity that all other entity classes generated by Linq2sql designer inherit from. public abstract class Entity { public virtual Guid ID { get; protected set; } } public partial class User : monius.Data.Entity { } And the following generated by L2S designer (DataModel.designer.cs) [Column(Storage = "_ID", AutoSync = AutoSync.OnInsert, DbType = "UniqueIdentifier NOT NULL", IsPrimaryKey = true, IsDbGenerated = true, UpdateCheck = UpdateCheck.Never)] [DataMember(Order = 1)] public System.Guid ID { get { return this._ID; } set { if ((this._ID != value)) { this.OnIDChanging(value); this.SendPropertyChanging(); this._ID = value; this.SendPropertyChanged("ID"); this.OnIDChanged(); } } } When I compile the code VS warns me that Warning 1 'User.ID' hides inherited member 'Entity.ID'. To make the current member override that mplementation, add the override keyword. Otherwise add the new keyword. That warning is obvious and I have to change the code generated by L2S designer (DataModel.designer.cs) to […] public override System.Guid ID { … protected set … } And the code compiled with no error or warning and everyone is happy. But that is not the end of story. As soon as I made changes to entities of the diagram (dbml) or even I open dbml file to view it, any change manually I made to designer has been vanished and POOF! Redo AGAIN. That is a painful job. Now I wonder if there is a way to force L2S designer not changing portions of auto-generated code. I’ll be appreciated if someone kindly helps me with this issue.

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  • Use LINQ to group a sequence by date with no gaps

    - by Codesleuth
    I'm trying to select a subgroup of a list where items have contiguous dates, e.g. ID StaffID Type Title ActivityDate -- ------- ---- ----------------- ------------ 1 41 1 Doctors 07/06/2010 2 41 0 Meeting with John 08/06/2010 3 41 0 Meeting Continues 09/06/2010 4 41 0 Meeting Continues 10/06/2010 5 41 3 Annual Leave 11/06/2010 6 41 0 Meeting Continues 14/06/2010 I'm using a pivot point each time, so take the example pivot item as 3, I'd like to get the following resulting contiguous events around the pivot: ID StaffID Type Title ActivityDate -- ------- ---- ----------------- ------------ 2 41 0 Meeting with John 08/06/2010 3 41 0 Meeting Continues 09/06/2010 4 41 0 Meeting Continues 10/06/2010 My current implementation is a laborious "walk" into the past, then into the future, to build the list: var orderedEvents = activities.OrderBy(a => a.ActivityDate).ToArray(); // Walk into the past until a gap is found var preceedingEvents = orderedEvents.TakeWhile(a => a.ID != activity.ID); DateTime dayBefore; var previousEvent = activity; while (previousEvent != null) { dayBefore = previousEvent.ActivityDate.AddDays(-1).Date; previousEvent = preceedingEvents.TakeWhile(a => a.ID != previousEvent.ID).LastOrDefault(); if (previousEvent != null) { if (previousEvent.ActivityDate.Date == dayBefore) relatedActivities.Insert(0, previousEvent); else previousEvent = null; } } // Walk into the future until a gap is found var followingEvents = orderedEvents.SkipWhile(a => a.ID != activity.ID); DateTime dayAfter; var nextEvent = activity; while (nextEvent != null) { dayAfter = nextEvent.ActivityDate.AddDays(1).Date; nextEvent = followingEvents.SkipWhile(a => a.ID != nextEvent.ID).Skip(1).FirstOrDefault(); if (nextEvent != null) { if (nextEvent.ActivityDate.Date == dayAfter) relatedActivities.Add(nextEvent); else nextEvent = null; } } The list relatedActivities should then contain the contiguous events, in order. Is there a better way (maybe using LINQ) for this? I had an idea of using .Aggregate() but couldn't think how to get the aggregate to break out when it finds a gap in the sequence.

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  • Linq causes collection to disappear when trying to use OrderByDescending

    - by Jeremy B.
    For background, I am using MongoDB and Rob Conery's linq driver. The code I am attempting is thus: using (var session = new Session<ContentItem>()) { var contentCollection = session.QueryCollection.Where(x => x.CreatedOn < DateTime.Now).OrderByDescending(y => y.CreatedOn).ToList(); ViewData.Model = contentCollection; } this will work on one machine, but on another machine I get back no results. To get results i have to do using (var session = new Session<ContentItem>()) { var contentCollection = session.QueryCollection.Where(x => x.CreatedOn < DateTime.Now).ToList(); ViewData.Model = contentCollection.OrderByDescending(y => y.CreatedOn).ToList(); } I have to do ToList() on both lines, or no results. If I try to chain anything it breaks. This is the same project, all dll's are locally loaded. Both machines have the same framework, versions of Visual studio and addons. the only difference is one has VisualSVN the other AnkhSVN. I can't see those causing the problem. Also, while debugging, on the machine that does not work you can see the items in the collection, and if you remove ordering all together it will work. This has got me completely stumped.

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  • Problem with LINQ in C#

    - by David Bonnici
    I am encountering a problem when using LINQ in C#, I am constantly getting "Specified cast is not valid". This is what I am trying to do. I create a class in which I declare all the columns of the table. [Table(Name="tbl_Aff")] public class Affiliate { [Column] public string name; [Column] public string firstname; [Column] public string surname; [Column] public string title; } I then declare a strongly typed DataContext in which I declare all Table collections as members of the context. public partial class Database : DataContext { public Table affiliate; public Database() : base(Settings.getConnectionString()) { } //This method gets the connection string by reading from an XML file. } public partial class Default : System.Web.UI.Page { protected void Page_Load(object sender, EventArgs e) { Database database = new Database(); try { var q = from a in database.affiliate select a; foreach (var aff in q) // Here I get the error "Specified cast is not valid" { lblMessage.InnerHtml += aff.name + ""; } } catch (Exception ex) { System.Console.WriteLine(ex.Message); } } }

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  • SQLce DAL Linq to Sql or EntityFramework

    - by bretddog
    Hi, I'm learning databases, using SqlCe, and need business object to database mapping. Currently I try to decide if to use Linq to Sql, or EntityFramework. (I understand a bit L2S, but haven't familiarized with EF yet) The program will only be debeloped and used by myself, so I have good control of the priorities: I don't need to consider potential change of database type or data storage type, as I'm quite certain SQLce will stay sufficient. I DO expect continued development and changes to the data scheme while the program is in active use; change business object properties (Hence database columns), and possibly overall table scheme. So old data must be transported to new scheme. I also want to keep a decent degree of layer separation DAL/BLL, although this may not be necessary, it is good for me to learn these principles. My question is: With these priorities, would I have any benefit by choosing either Linq2Sql vs. EntityFramwork? (and please explain why) Btw, the project involves very simple table scheme with only 4-5 tables and very simple relations. Thanks!

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