Sorting A List Of Objects By An Object's Field?
Mar 25, 2011
Let's say I have the following class:
[Code]....
Now let's say I have a list of these objects.
[Code]....
How can I sort this book list by the Book object's BookID property?
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Jan 28, 2010
I have 2 tables; they have a many-to-many relationship. One is called Blog the other is Tag.
A Blog can contain a List of Tag objects. How can I go about getting all blogs that have a passed in tag name using lambda expressions?
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Nov 17, 2010
have some Objects, lets say Employee and Role defined as below and I have defined relationships in my database that gives me a list of objects say employees and thanks to my framework each employee object also has a Role object linked via the RoleIDID, UserName, Password, Email, RoleIDRoleID, RoleNameSo in code I can do something like this
Employee emp = dataService_GetEmployeeByID(1);
string RoleName = emp.Role.RoleName;
Now here is my problemI can bind any object in a repeater and it works fine for the first level in my relationship
For instance <%# Eval("UserName") %>
But I need to be able to show the details for my child objects as well (Role) so something like this (which does not work)
<%# Eval("Role.RoleName") %>
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Apr 6, 2010
I know how to bind a simple objects to a dropdown list. However I am having problems binding my objects which contains sub objects to the control.i.e. with simple object i just do ddl.DataValueField = "myproperty"
with my objects they contains sub objects which i want to bind. I have tried ddl.DataValueField = "sub-object.myproperty" which doesnt work.
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Feb 1, 2010
I am trying to get the value of the id field in my gridview but I keep coming up with this error when i do selectedValue or selecteIndex
Exception Details: System.NullReferenceException: Object reference not set to an instance of an object.
How do I get that id? What I am trying to do is when the user select that link it will delete that information from the database. Here's my code:
[Code]....
[Code]....
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Aug 12, 2010
I am trying to return an object from a web service and having trouble with the sorting. See the code below where the Order By is a.Account_Number. I need to be able to replace that with a the dynamic value strSort that is being passed to the function.
[Code]....
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Feb 23, 2010
i'm trying to sort a datatable using the typical select method*. The problem comes because the field is string defined but it's containing integer values.
With sql the problem will be solved just using something like:
select * from table order by to_number(field);
but of course it's not working properly with the method commented above (select method).
*http://msdn.microsoft.com/en-gb/library/b5c0xc84(VS.80).aspx
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Feb 24, 2010
Currently i am having a list like List<Tickets> allTickets.I need to select in the same list some corresponding info about the ticket writer like List<Ticket, aspnet_User>.
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Feb 11, 2010
I'm kinda new to web services and want to make sure I am doing things correctly.
I have a custom object which has sub objects as well. (let's say Company object, sub object is collection of Employee objects)
I want the web service to return a collection of Company objects. Do I make the service return a Dataset and custom generate a dataset with datatables representing the different objects?
What is the best way to do this? I tried to just serialize it, but that doesn't seem to work either.
I tried this dll
[URL]
But the output XML doesn't seem to include the sub object.
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Feb 16, 2010
I have written a page which uses Linq to query the database and bind the resulting IQueryable to a datagrid. I have a partial class which contains extra properties which derive their values based on other values brought in from the database.
Sorting works fine on fields that are actually in the database but not for the derived fields. When I attempt to sort on such a field I get an error saying "The member 'Trip.Difference' has no supported translation to SQL. how to allow sorting on these derived fields?
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Feb 2, 2011
I am using Object Data Source to bind data in the gridview. I haveset the property AllowSorting=true. While running the application, Icould sort the data only in ascending order. Is there any way toachieve two way sorting in gridview ie. both ascending and descendingon successive clicks ?.
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Oct 1, 2010
although i had to take the table that has my calculated column and make a view (so i could filter) and then bind the gridview to the view.
My question is as this.
1.) in order to get my calculated field i had to load my data into a table (as suggested)
2.)Add a column to the table and perform calculations
3.)make a dataview from the tables because i could not get the Gridview.datasource= ds.tables("loads").select("Deadhead <= " & sngRadius
4.)the largest of the 3 tables my query is based on contains about 7000 records. The way i have the logic & programming now everytime a new "truck location" is put in the textbox1 and "find loads/button1" is clicked. It calculates the deadhead miles of all 7000 records before filtering. I am filtering based on the deadhead miles.
Does anyone have any recomendation about how to speed this up a bit.
Also in order to get paging to work i had to rebind/filter the data again ... means looping through all 7000 records each time paging is called. This seems terribly ineffecient as i am already forced to use access instead of SQL.
Would i see a performance increase if i installed SQL or mySQL and create linked tables to the ones i use in access. or would access still be the bottleneck?
I don't know if the performance increase would be negligible as i still ultimately be getting the data from Access.
I have posted the entire code for the page below. When i originally started i didn't think there would be to much code so i left it all on one page instead of using code-behind. Would i gain anything by swapping to code-behind now?
[Code]....
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Jun 21, 2010
I have a list of objects (List1) and I am trying to make a copy of this list (List2) and then change one of the fields in the new list.I used :
List<MyObj> List2 = new List<MyObj>();
List2.AddRange(List1);
I alos tried:
List<MyObj> List2 = new List<MyObj>(List1);
But regardless of the method, when I do:
foreach (MyObj o in List2)
o.some_field = 2
it not only changes the field in Lis2 but alos in List1. Not sure what I am missing here.
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Jul 2, 2010
I found some code on the web and it threw me off. Look at the code below. You will notice only when the Hits == 1, does the cache get added. After that, the cache object isn't updated. It begs the question, does the object when updated, update the cache as well automatically? The answer here would make me remove some code in some of my classes.
public static bool IsValid( ActionTypeEnum actionType )
{
HttpContext context = HttpContext.Current;
if( context.Request.Browser.Crawler ) return false;
string key = actionType.ToString() + context.Request.UserHostAddress;
var hit = (HitInfo)(context.Cache[key] ?? new HitInfo());
if( hit.Hits > (int)actionType ) return false;
else hit.Hits ++;
if( hit.Hits == 1 )
context.Cache.Add(key, hit, null, DateTime.Now.AddMinutes(DURATION),
System.Web.Caching.Cache.NoSlidingExpiration,
System.Web.Caching.CacheItemPriority.Normal, null);
return true;
}
I would only guess that I would need to add the lines after the if statement:
if( hit.Hits == 1 )
context.Cache.Add(key, hit, null, DateTime.Now.AddMinutes(10),
System.Web.Caching.Cache.NoSlidingExpiration,
System.Web.Caching.CacheItemPriority.Normal, null);
else if (hit.Hits > 1)
{context.Cache.Remove(key);
context.Cache.Add(key, hit, null, DateTime.Now.AddMinutes(10),
System.Web.Caching.Cache.NoSlidingExpiration,
System.Web.Caching.CacheItemPriority.Normal, null);
}
Found the code at the bottom of the page here: http://www.codeproject.com/KB/aspnet/10ASPNetPerformance.aspx?msg=2809164
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Mar 29, 2011
I have a dropdownlist dynamically filled from file folder and the dropdown filled with the name of the files in the folder like
JUN-2010,APR-2010,MAY-2010,SEP-2010,FEB-2011,DEC-2010
How can I sort this dropdownlist ?
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Jul 19, 2010
I want to sort my gridview binded to an object datasource fetching business objects. I have already implemented custom paging & now want to implement sorting. Just read this article but there is lot of concatenation going on there with the SQL Query.
[URL]
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Jun 22, 2010
I have a gridview control set up like so:
[Code]....
I am using an IComparer to do the sorting of the gridview and binding it to a list of objects. It used to be that the linkbutton in the first template field was being done like this:
[Code]....
The sorting worked just fine when it was like this, but I would prefer not to use a querystring value. The problem with using the linkbutton is that the sorting appears to work (there are only two rows in my test case and they change places), but when the linkbutton is clicked on it is in the same order before the sort took place. After each sort the gridview's datasource is reset to the newly sorted list of objects and the databind method is called.
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Dec 20, 2010
I have a list of objects and I would like to create my own custom control that pages through the list using Jquery to make the Ajax calls to my pager methods. I've had some experience with Jquery but need a helping hand and I really don't want to use update panels etc. So the scenario is.....user clicks next, the C# method is called using Ajax, the code gets the relevant data and sends re-populates the UI with the next item in the list.
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Jun 24, 2010
i want to store a list of objects in session
List<ContentQueueLog> inactiveContent = GetInActiveContent(this.userID, this.visitorID);
when i store this list in sesssion it is stored but while trhying to get its null.
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Mar 17, 2010
I'm using asp.net mvc2 and trying to send a list of json objects with hard coded values from the home controller, and receive them in index.... in the code below i'm sending 1 json object. how do i send many?
in home controller:
[Code]....
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Jan 23, 2010
I have a List of objects in an asp.net page. when the page loads in the browser for the first time, I fetch data from the database, create objects with those data and populate the list. All these are done inside the page load event handler. Now when the page is posted back to the page, the previous list is gone, since the variables were all freed.
How can I cache that List, so that when this page is posted back, all my objects are available?
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Mar 10, 2011
Action method takes as id parameter and returns 2 lists (eg. List<object1> and List<object2>) of objects back to the view. In order to achieve this, the viewmodel is created as below;
ViewModel
{
Int id;
[code]...
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Mar 12, 2011
I am making my first attempt at using RenderPartial to display a list of objects, but so far having little success. Here is my code, can somebody give me some guidance on what I am doing wrong?
[Code]....
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Dec 20, 2010
I finding myself repeating myself and the DRY side is nagging me to find an abstraction. I have a number of different entities in an MVC3 Razor web app. They are all business objects and each has a number of different properties that I show to the user in a list. So I have Index views and List partial views for each of these different entities (there are at least 10). I would like to abstract the List partial view so that it's capable of displaying a list of any type of entity. It simply shows them in a table with a column for each property and a row for each entity. My current thinking is that I could receive a list of objects and then use Reflection to see what properties those objects have and use those to make columns. I really wish I could receive a generic List somehow and from my various controllers just pass in an anonymous object (new {Parameter 1=param1, Parameter 2=param2}, etc.) but then I discovered that it's not possible to pass anonymous objects around.
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Aug 14, 2010
I used Object Test Bench to test my classes in VS 2008 professional edition . Right click on Class name and then selected create instance ,then its Constructor, there comes a dialog box, that just gives a message and a TextBox field is present there, i filled that field with any name and clicked OK.Then error message comes that "Create Instance Failed" and its error code is "0x80004005" . What's this ? How to instantiate object of my classes ?
But with the same procedure i can create object in WPF applications. What is problem with asp.net ?
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