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  • Filtering subsets using Linq

    - by Nathan Matthews
    Hi All, Imagine a have a very long enunumeration, too big to reasonably convert to a list. Imagine also that I want to remove duplicates from the list. Lastly imagine that I know that only a small subset of the initial enumeration could possibly contain duplicates. The last point makes the problem practical. Basically I want to filter out the list based on some predicate and only call Distinct() on that subset, but also recombine with the enumeration where the predicate returned false. Can anyone think of a good idiomatic Linq way of doing this? I suppose the question boils down to the following: With Linq how can you perform selective processing on a predicated enumeration and recombine the result stream with the rejected cases from the predicate?

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  • MVC | Linq Update Query | Help!

    - by 109221793
    Hi guys, I'm making modifications to a C# MVC application that I've inherited. I have a database, and for simplicity I'll just focus on the two tables I'm working with for this linq query. Item ItemID Int PK ItemName RepairSelection (Yes or No) RepairID Int FK Repair RepairID Int PK RepairCategory SubmissionDate DateSentForRepair Ok, so ItemID is pretty much the identifier, and the View to display the Repair details goes like this (snippet): <%= Html.LabelFor(x => x.ItemID)%> <%= Html.DisplayFor(x => x.ItemID)%><br /> <%= Html.LabelFor(x => x.Repair.RepairCategory)%> <%= Html.DisplayFor(x => x.Repair.RepairCategory, "FormTextShort")%><br /> <%= Html.LabelFor(x => x.Repair.SubmissionDate)%> <%= Html.DisplayFor(x => x.Repair.SubmissionDate)%><br /> <%= Html.LabelFor(x => x.Repair.DateSentForRepair)%> <%= Html.DisplayFor(x => x.Repair.DateSentForRepair)%><br /> <%= Html.ActionLink("Edit Repair Details", "Edit", new { ItemID= Model.ItemID})%> Here is the GET Edit action: public ActionResult Edit(Int64? itemId) { ModelContainer ctn = new ModelContainer(); var item = from i in ctn.Items where i.ItemID == itemId select i; return View(item.First()); } This is also fine, the GET Edit view displays the right details. Where I'm stuck is the linq query to update the Repair table. I have tried it so many ways today that my head is just fried (new to Linq as you may have guessed). My latest try is here (which I know is way off so go easy ;-) ): [HttpPost] public ActionResult Edit(Int64 itemId, Repair repair, Item item, FormCollection formValues) { if (formValues["cancelButton"] != null) { return RedirectToAction("View", new { ItemID = itemId }); } ModelContainer ctn = new ModelContainer(); Repair existingData = ctn.Repair.First(a => a.RepairId == item.RepairID && item.ItemID == itemId); existingData.SentForConversion = DateTime.Parse(formValues["SentForConversion"]); ctn.SaveChanges(); return RedirectToAction("View", new { ItemID = itemId }); } For the above attempt I get a Sequence Contains No Elements error. Any help or pointers would be appreciated. Thanks guys.

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  • LINQ - group specific types of classes

    - by Nelson
    This question is similar to http://stackoverflow.com/questions/2835192/linq-group-one-type-of-item but handled in a more generic way. I have a List that has various derived classes. I may have something like this: List<BaseClass> list = new List<BaseClass>() { new Class1(1), new Class2(1), new Class1(2), new Class3(1), new Class2(2), new Class4(1), new Class3(2) }; I am trying to use LINQ to semi-sort the list so that the natural order is maintained EXCEPT for certain classes which have base.GroupThisType == true. All classes with GroupThisType should be grouped together at the place that the first class of the same type occurs. Here is what the output should be like: List<BaseClass> list = new List<BaseClass>() { new Class1(1), new Class1(2), new Class2(1), new Class3(1), new Class3(2) new Class2(2), new Class4(1), };

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  • LINQ in SQLite for Windows store app does not have 'ThenBy' to order by multiple columns

    - by user1131657
    I have a Windows 8 store application and I'm using the latest version on SQLite for my database. So I want to return some records from the database and I want to order them by more that one column. However SQLite doesn't seem to have the ThenBy statement? So my LINQ statement is below: from i in connection.Table<MyTable>() where i.Type == type orderby i.Usage_Counter // ThenBy i.ID select i); So how do I sort by multiple columns in SQLite without doing another LINQ statement?

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  • Sort collection within collection using Linq

    - by user327066
    Hi, I have a one-to-many Linq query and I would like to sort on a property within the "many" collection. For example in the pseudo-code below, I am returned a List from the Linq query but I would like to sort / order the Products property based on the SequenceNumber property of the Product class. How can I do this? Any information is appreciated. Thanks. class Order { int OrderId; List<Product> Products; } class Product { string name; int SequenceNumber; }

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  • How to limit select items with L2E/S?

    - by orlon
    This code is a no-go var errors = (from error in db.ELMAH_Error select new { error.Application, error.Host, error.Type, error.Source, error.Message, error.User, error.StatusCode, error.TimeUtc }).ToList(); return View(errors); as it results in a 'requires a model of type IEnumerable' error. The following code of course works fine, but selects all the columns, some of which I'm simply not interested in: var errors = (from error in db.ELMAH_Error select error).ToList(); return View(errors); I'm brand spanking new to MVC2 + L2E, so maybe I'm just not thinking in the right mindset yet, but this seems counter-intuitive. Is there an easy way to select a limited number of columns, or is this just part of using an ORM?

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  • Linq To SQL: Retain list order when using .Contains

    - by rockinthesixstring
    I'm using Lucene.net to build a MyListOfIds As List(Of Integer) which I then pass on to my Linq service. I then search the database as follows Return _EventRepository.Read().Where(Function(e) MyListOfIds.Contains(e.ID)).ToList Now I know that Lucene is already ordering MyListOfIds based on the weight it gave each term. What sucks is that Linq is losing that order in it's SQL search. My Question: How can I retain that sort order when building my Lambda expression? I tried using LINQPad to see how the query is being built, but because I had to declare a variable LINQPad didn't show me the resultant SQL :-( Here's what I tried in LINQPad Dim i As New List(Of Integer) i.Add(1) i.Add(100) i.Add(15) i.Add(3) i.Add(123) Dim r = (From e In Events Where i.Contains(e.ID) Select e) note: my example is in VB.NET, but I don't mind if responses are in C#

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  • Duplicate a database record with linq

    - by holz
    Is there a way to duplicate a db record with linq to sql in c#? Id [int] IDENTITY(1,1) NOT NULL PRIMARY KEY, [Foo] [nvarchar](255) NOT NULL, [Bar] [numeric](28,12) NOT NULL, ... Given the table above, I would like to duplicate a record (but give it a different id), in a way that new fields added to the DB and the Linq dbml file at a later date will still get duplicated with out having to change that code that duplicates the record. ie I don't want to write newRecord.Foo = currentRecord.Foo; for all of the fields on the table.

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  • Multiple fields from LINQ to Text Box

    - by Chuki2
    how can I pass value from selected field (LINQ) to textbox in winforms? If single fields, I just do like this var result = from row in dtValueBranch.AsEnumerable() where row.Field<int>("branchID") == idBranch select row.Field<string>("branchName"); StringBuilder sb = new StringBuilder(); foreach (string s in result) { sb.Append(s + Environment.NewLine); } tbBranch.Text = sb.ToString(); So this is the code LINQ to many fields var result = from row in dtValueBranch.AsEnumerable() where row.Field<int>("branchID") == idBranch select new { BranchName = row["branchName"].ToString(), branchTel = row["branchTel1"].ToString(), // And many more fields }; How can I to implement each fields to each textbox?

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  • LINQ to SQL auto-generated type for stored procedure

    - by StuffHappens
    Hello. I have the following stored procedure ALTER PROCEDURE [dbo].Test AS BEGIN CREATE TABLE ##table ( ID1 int, ID2 int ) DECLARE @query varchar(MAX); INSERT INTO ##table VALUES(1, 1); SELECT * FROM ##table; END And I try to use it from C# code. I use LINQ to SQL as an O/RM. When I add the procedure to DataBaseContext it says that it can't figure out the return value of this procedure. How to modify the stored procedure so that I can use it with LINQ to SQL. Note: I need to have global template table!

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  • Building a linked list with LINQ

    - by FreshCode
    What is the fastest way to order an unordered list of elements by predecessor (or parent) element index using LINQ? Each element has a unique ID and the ID of that element's predecessor (or parent) element, from which a linked list can be built to represent an ordered state. Example ID | Predecessor's ID --------|-------------------- 20 | 81 81 | NULL 65 | 12 12 | 20 120 | 65 The sorted order is {81, 20, 12, 65, 120}. An (ordered) linked list can easily be assembled iteratively from these elements, but can it be done in fewer LINQ statements? Edit: I should have specified that IDs are not necessarily sequential. I chose 1 to 5 for simplicity. See updated element indices which are random.

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  • Where Not In OR Except simulation of SQL in LINQ to Object(C#)

    - by Thinking
    Suppose I have two lists that holds the list of source file names and destination file names respectively. The Sourcefilenamelist has files as 1.txt, 2.txt,3.txt, 4.txt while the Destinaitonlist has 1.txt,2.txt. I ned to write a linq query to find out which files are in SourceList that are absent in DestinationFile list. e.g. here the out put will be 3.txt and 4.txt. I have done this by a foreach statement.. but now I want to do the same by using LINQ(C#). Help needed. Thanks

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  • Linq Order By a subtable

    - by Michael
    Hello, My question is how to sort a Linq query by a sub table: Table Apps: - app_id - name Table AppStatus: - app_status_id - app_id - severity - status_date I would like to have a query with all the apps, sorted by the last status severity: app_id name 1 first 2 second 3 third app_status_id app_id severity status_date 1 1 5 12-4-2010 2 1 2 15-4-2010 3 2 7 10-4-2010 4 3 3 13-4-2010 Now i want it sorted like: app_id name 3 third 1 first 2 second Can anyone help me with a LINQ query for this. I tried the following already, but that didn't work: var apps = from apps in dc.Apps orderby apps.AppStatus.LastOrDefault().severity select apps;

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  • Doing a UNION ALL on two different COUNTs using Linq-To-Sql

    - by Danno
    Is it possible to write a linq-to-sql statement that will return two different COUNTs that have been put into a single dataset using UNION ALL? I know this is syntactically wrong but here's what I'm trying to do: (from t1 in TableOne select t1).Count().Union( (from t2 in TableTwo select t2).Count() ) Here's the sql I would like would like to have generated: select count(*) from TableOne union all select count(*) from TableTwo I realize that Count() returns an int and does not have a Union method on it and therein lies my question. Can Linq-to-Sql be written that will achieve what I'm after?

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  • Transform LINQ Dataset into a Matrix for export

    - by Mad Halfling
    Hi folks, I've got a data table with columns in which include Item, Category and Value (and others, but those are the only relevant ones for this problem) that I access via LINQ in a C# ASP.Net MVC app. I want to transform these into a matrix and output that as a CSV file to pull into Excel as matrix with the items down the side, the categories across the top and the values in the row cells. However, I don't know how many, or what, categories there will be in this table, nor will there always be a record for each item/category combination. I've written this by looping round, getting my "master category" list, then looking again for each item, filling in either blank or Value, depending on whether the item/category record exists, but as there are currently 27000 records in the table, this isn't as fast as I'd like. Is there a slicker and faster way I can do this, maybe via LINQ (firing into a quicker SQL statement so the DB server can do the leg-work), or will any method essentially come back to what I am doing? Thx MH

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  • Use LINQ to insert data from dataset to SQL

    - by Mayo
    Let's say I have a dataset in an ASP.NET website (.NET 3.5) with 5 tables, each has roughly 30,000 rows and an average of 12 columns. I want to insert all of the data from the dataset into 5 very-similar-but-not-quite-identical tables in SQL Server 2008. I also want to use LINQ (personal preference - trying to learn something new). Is it as simple as iterating through the dataset and, for each row, creating a new instance of the associated class, initializing its data with the dataset's row, adding it to the data model, and then doing one giant SubmitChanges at the end? Are there better ways of doing this with LINQ? Or is this the de-facto standard?

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  • How does linq decide between inner & outer joins

    - by user287795
    Hi Usually linq is using an left outer join for its queries but on some cases it decides to use inner join instead. I have a situation where that decision results in wrong results since the second table doesn't always have suitable records and that removes the records from the first table. I'm using a linqdatasource over a dbml where the relevant tables are identical but one holds historical records removed from the first. both have the same primary key. and I'm using a dataloadoption to load both tables at once with out round trips. Would you explain why linq decided to use an inner join here? Thanks

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  • EF Query with conditional include that uses Joins

    - by makerofthings7
    This is a follow up to another user's question. I have 5 tables CompanyDetail CompanyContacts FK to CompanyDetail CompanyContactsSecurity FK to CompanyContact UserDetail UserGroupMembership FK to UserDetail How do I return all companies and include the contacts in the same query? I would like to include companies that contain zero contacts. Companies have a 1 to many association to Contacts, however not every user is permitted to see every Contact. My goal is to get a list of every Company regardless of the count of Contacts, but include contact data. Right now I have this working query: var userGroupsQueryable = _entities.UserGroupMembership .Where(ug => ug.UserID == UserID) .Select(a => a.GroupMembership); var contactsGroupsQueryable = _entities.CompanyContactsSecurity;//.Where(c => c.CompanyID == companyID); /// OLD Query that shows permitted contacts /// ... I want to "use this query inside "listOfCompany" /// //var permittedContacts= from c in userGroupsQueryable //join p in contactsGroupsQueryable on c equals p.GroupID //select p; However this is inefficient when I need to get all contacts for all companies, since I use a For..Each loop and query each company individually and update my viewmodel. Question: How do I shoehorn the permittedContacts variable above and insert that into this query: var listOfCompany = from company in _entities.CompanyDetail.Include("CompanyContacts").Include("CompanyContactsSecurity") where company.CompanyContacts.Any( // Insert Query here.... // b => b.CompanyContactsSecurity.Join(/*inner*/,/*OuterKey*/,/*innerKey*/,/*ResultSelector*/) ) select company; My attempt at doing this resulted in: var listOfCompany = from company in _entities.CompanyDetail.Include("CompanyContacts").Include("CompanyContactsSecurity") where company.CompanyContacts.Any( // This is concept only... doesn't work... from grps in userGroupsQueryable join p in company.CompanyContactsSecurity on grps equals p.GroupID select p ) select company;

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