IRepositoryBase
IQueryable<T> GetAll(Expression<Func<T, bool>> predicate = null, params Expression<Func<T, object>>[] includes);
RepositoryBase
public IQueryable<T> GetAll([OptionalAttribute][DefaultParameterValueAttribute(null)]Expression<Func<T, bool>> predicate, params Expression<Func<T, object>>[] includes)
{
var set = CreateSet().IncludeMultiple(includes);
return (predicate == null) ? set : set.Where(predicate);
}
IAccountService
IEnumerable<int> GetAllReferenceIds();
AccountService
public IEnumerable<int> GetAllReferenceIds()
{
var accountOwners = _accountOwnerRepository.GetAll();
return accountOwners.Select(m => m.ReferenceId).ToList();
}
AccountController
public ActionResult ReferenceIdPartial()
{
ViewData["AccountOwners"] = accountOwnerService.GetAllReferenceIds();
return PartialView();
}
MVC Partial View - devexpress combobox mvc extension
settings.Properties.Columns.Add("ReferenceId", "Reference Id", Unit.Percentage(100));
Error - column ReferenceId Not found
I am sending a collection of int through GetReferenceIds()
Is there a way to call the columns from Controller. Something like AccountOwner(a=>a.ReferenceIds, select ReferenceIds) - I should be able to get the column name as well as the data.
Thanks for your time.
This is a shot into the dark, I actually only understand your last sentence "I should be able to get the column name as well as the data" - and could imagine that if you bind a collection to a combobox (I don't know the DevExpress combobox extension) the combobox control wants a collection of class objects with a property name/property value pair instead of only a collection of values ( int). So, without touching the AccountService you could try:
public ActionResult ReferenceIdPartial()
{
ViewData["AccountOwners"] = accountOwnerService.GetAllReferenceIds()
.Select(i => new { ReferenceId = i });
return PartialView();
}
ViewData["AccountOwners"] now would hold a collection of (anonymous) objects. Each object has one property called ReferenceId with a value i fetched from the Ids you returned from your service.
Related
I have an ASP.NET MVC 3 application that uses custom attributes to create select controls for model properties that can be populated from external data sources at runtime. The issue is that my EditorTemplate output appear to be cached at the application level, so my drop down lists are not updated when their data source changes until the Application Pool is recycled.
I also have output the contents of the MVC 3 ActionCache that is bound to the ViewContext.HttpContext object as shown in the MVC 3 source code in System.Web.Mvc.Html.TemplateHelpers.cs:95.
Action Cache GUID: adf284af-01f1-46c8-ba15-ca2387aaa8c4:
Action Cache Collection Type: System.Collections.Generic.Dictionary``2[System.String,System.Web.Mvc.Html.TemplateHelpers+ActionCacheItem]
Action Cache Dictionary Keys: EditorTemplates/Select
So it appears that the Select editor template is definitely being cached, which would result in the TemplateHelper.ExecuteTemplate method to always return the cached value instead of calling ViewEngineResult.View.Render a second time.
Is there any way to clear the MVC ActionCache or otherwise force the Razor view engine to always re-render certain templates?
For reference, Here are the relevant framework components:
public interface ISelectProvider
{
IEnumerable<SelectListItem> GetSelectList();
}
public class SelectAttribute : Attribute, IMetadataAware
{
private readonly ISelectProvider _provider;
public SelectAttribute(Type type)
{
_provider = DependencyResolver.Current.GetService(type) as ISelectProvider;
}
public void OnMetadataCreated(ModelMetadata modelMetadata)
{
modelMetadata.TemplateHint = "Select";
modelMetadata.AdditionalValues.Add("SelectListItems", SelectList);
}
public IEnumerable<SelectListItem> SelectList
{
get
{
return _provider.GetSelectList();
}
}
}
Next, there is a custom editor template in ~\Views\Shared\EditorTemplates\Select.cshtml.
#model object
#{
var selectList = (IEnumerable<SelectListItem>)ViewData.ModelMetadata.AdditionalValues["SelectListItems"];
foreach (var item in selectList)
{
item.Selected = (item != null && Model != null && item.Value.ToString() == Model.ToString());
}
}
#Html.DropDownListFor(s => s, selectList)
Finally, I have a view model, select provider class and a simple view.
/** Providers/MySelectProvider.cs **/
public class MySelectProvider : ISelectProvider
{
public IEnumerable<SelectListItem> GetSelectList()
{
foreach (var item in System.IO.File.ReadAllLines(#"C:\Test.txt"))
{
yield return new SelectListItem() { Text = item, Value = item };
}
}
}
/** Models/ViewModel.cs **/
public class ViewModel
{
[Select(typeof(MySelectProvider))]
public string MyProperty { get; set; }
}
/** Views/Controller/MyView.cshtml **/
#model ViewModel
#using (Html.BeginForm())
{
#Html.EditorForModel()
<input type="submit" value="Submit" />
}
** EDIT **
Based on suggestions in the comment, I started to look more closely at the ObjectContext lifecycle. While there were some minor issues, the issue appears to be isolated to an odd behavior involving a callback within a LINQ expression in the SelectProvider implementation.
Here is the relevant code.
public abstract class SelectProvider<R, T> : ISelectProvider
where R : class, IQueryableRepository<T>
{
protected readonly R repository;
public SelectProvider(R repository)
{
this.repository = repository;
}
public virtual IEnumerable<SelectListItem> GetSelectList(Func<T, SelectListItem> func, Func<T, bool> predicate)
{
var ret = new List<SelectListItem>();
foreach (T entity in repository.Table.Where(predicate).ToList())
{
ret.Add(func(entity));
}
return ret;
}
public abstract IEnumerable<SelectListItem> GetSelectList();
}
public class PrinterSelectProvider : SelectProvider<IMyRepository, MyEntityItem>
{
public PrinterSelectProvider()
: base(DependencyResolver.Current.GetService<IMyRepository>())
{
}
public override IEnumerable<SelectListItem> GetSelectList()
{
// Create a sorted list of items (this returns stale data)
var allItems = GetSelectList(
x => new SelectListItem()
{
Text = x.DisplayName,
Value = x.Id.ToString()
},
x => x.Enabled
).OrderBy(x => x.Text);
// Do the same query, but without the callback
var otherItems = repository.Table.Where(x => x.Enabled).ToList().Select(x => new SelectListItem()
{
Text = x.DisplayName,
Value = x.Id.ToString()
}).OrderBy(x => x.Text);
System.Diagnostics.Trace.WriteLine(string.Format("Query 1: {0} items", allItems.Count()));
System.Diagnostics.Trace.WriteLine(string.Format("Query 2: {0} items", otherItems.Count()));
return allItems;
}
}
And, the captured output from the System.Diagnostics.Trace is
Query 1: 2 items
Query 2: 3 items
I'm not sure what could be going wrong here. I considered that the Select may need an Expressions, but I just double-checked and the LINQ Select method only takes Func objects.
Any additional suggetions?
Problem Solved!
I finally had a chance to re-visit this issue. The root cause had nothing to do with LINQ, the ActionCache, or the ObjectContext, rather it was related to when attribute constructors are called.
As shown, my custom SelectAttribute class calls DependencyResolver.Current.GetService in its constructor to create an instance of the ISelectProvider class. However, the ASP.NET MVC framework scans the assemblies for custom metadata attributes once and keeps a reference to them in the application scope. As explained in the linked question, accessing a Attribute triggers its constructor.
So, the constructor was run only once, rather than on each request, as I had assumed. This meant that there was actually only one, cached instance of the PrinterSelectProvider class instantiated that was shared across all requests.
I solved the problem by changing the SelectAttribute class like this:
public class SelectAttribute : Attribute, IMetadataAware
{
private readonly Type type;
public SelectAttribute(Type type)
{
this.type = type;
}
public void OnMetadataCreated(ModelMetadata metadata)
{
// Instantiate the select provider on-demand
ISelectProvider provider = DependencyResolver.Current.GetService(type) as ISelectProvider;
modelMetadata.TemplateHint = "Select";
modelMetadata.AdditionalValues.Add("SelectListItems", provider.GetSelectList());
}
}
Tricky problem indeed!
I need to know how I could create a drop down list to represent all the categories in my "Categories" table.
I have already extracted the names and the values of each category I need, using this LINQ query :
var dbcontext = new LNQ2SQLDataContext();
var Q = from P in dbcontext.Categories
where P.SUB_CAT == null
select P;
I can pass this "Q" to my view like this :
In Controller :
return View(Q);
And in the View :
#model IEnumerable<MyAppName.Models.Category>
But I have no idea how to use #html.DropDownListFor() to make a darn good drop down list out of the model. :|
PLUS:
I could make a SelectList from the query "Q" like this :
var category_list = new SelectList(Q, "CAT_ID", "CAT_Name");
BUT I don't know how to create a drop down list (without using ViewBag to pass the category_list to the view) from a simple SelectList, either :|
I searched through as many blogs and websites as I could. But they didn't have the solution for my problem. I only got more and more confused!
So can anybody help please ? :/
To use DropDownListFor you'll either have to have a model that has a SelectList or data to make a selectlist out of and a property to store the selected value of the dropdown OR use the ViewBag to pass the category_list. So you can go with...
Public Class MyViewModel
{
Public Integer SelectedCategory { get; set; }
Public SelectList Categories { get; set; }
}
Public Class ItemsController : Controller
{
Public ActionResult Index()
{
var dbcontext = new LNQ2SQLDataContext();
var Q = from P in dbcontext.Categories
where P.SUB_CAT == null
select P;
var vm = new MyViewModel();
vm.Categories = new SelectList(Q, "CategoryID", "Name");
return View(vm);
}
[HttpPost()]
Public ActionResult Index(MyViewModel vm)
{
var theSelectedCategory = vm.SelectedCategory;
}
}
The view would be...
#model MyViewModel
#Html.DropDownListFor(model => model.SelectedCategory, Model.Categories, "Select Category")
Note: I don't typically code in C# so I can't guarantee the syntax is exactly right.
I need to show my list in a RadioButtonList , some thing like this:
#Html.RadioButtonList("FeatureList", new SelectList(ViewBag.Features))
But as you know there is no RadioButtonList class in HTML Helper class and when I use :
#Html.RadioButton("FeatureList", new SelectList(ViewBag.Features))
it shows me a blank list!
// Controller codes :
public ActionResult Rules()
{
ViewBag.Features = (from m in Db.Features where m.ParentID == 3 select m.Name);
return View();
}
Html.RadioButton does not take (string, SelectList) arguments, so I suppose the blank list is expected ;)
You could 1)
Use a foreach over your radio button values in your model and use the Html.RadioButton(string, Object) overload to iterate your values
// Options could be a List<string> or other appropriate
// data type for your Feature.Name
#foreach(var myValue in Model.Options) {
#Html.RadioButton("nameOfList", myValue)
}
or 2)
Write your own helper method for the list--might look something like this (I've never written one like this, so your mileage may vary)
public static MvcHtmlString RadioButtonList(this HtmlHelper helper,
string NameOfList, List<string> RadioOptions) {
StringBuilder sb = new StringBuilder();
// put a similar foreach here
foreach(var myOption in RadioOptions) {
sb.Append(helper.RadioButton(NameOfList, myOption));
}
return new MvcHtmlString(sb.ToString());
}
And then call your new helper in your view like (assuming Model.Options is still List or other appropriate data type)
#Html.RadioButtonList("nameOfList", Model.Options)
This problem occurs in both NHibernate 2 and 3. I have a Class A that has a member set of class B. Querying the classes directly executes nicely. But when I pass one of the expressions involving class B into a method I get the following error:
System.ArgumentException: Object of type 'System.Linq.Expressions.ConstantExpression' cannot be converted to type 'System.Linq.Expressions.LambdaExpression'.
As far as I can see I am passing the exact same expression into the Any() method. But for some reason they are treated differently. I have done some debugging and it looks like in the first method, the expression is treated as an expression with NodeType 'Quote', while the same expression in the 2nd method seems to be treated as an expression with NodeType 'Constant'. The parent expression of the expression in the 2nd method has a NodeType 'MemberAccess'. So it looks like the expression tree is different in the different test methods. I just don't understand why and what to do to fix this.
Classes involvend:
public class A
{
public virtual int Id { get; set; }
public virtual ISet<B> DataFields { get; set; }
}
public class B
{
public virtual int Id { get; set; }
}
Sample test code:
[TestMethod]
public void TestMethod1()
{
using (ISession session = sessionFactory.OpenSession())
{
var records = session.Query<A>()
.Where<A>(a => a.DataFields
.Any(b => b.Id == 1));
Console.Write("Number of records is {0}", records.Count());
}
}
[TestMethod]
public void TestMethod2()
{
GetAsWhereB(b => b.Id == 1);
}
private void GetAsWhereB(Func<B, bool> where)
{
using (ISession session = sessionFactory.OpenSession())
{
var records = session.Query<A>()
.Where(a => a.DataFields
.Any(where));
Console.Write("Number of records is {0}", records.Count());
}
}
This is one problem:
private void GetAsWhereB(Func<B, bool> where)
That's taking a delegate - you want an expression tree otherwise NHibernate can't get involved. Try this:
private void GetAsWhereB(Expression<Func<B, bool>> where)
As an aside, your query is hard to read because of your use of whitespace. I would suggest that instead of:
var records = session.Query<A>().Where<A>(a => a.DataFields.
Any(b => b.Id == 1));
you make it clear that the "Any" call is on DataFields:
var records = session.Query<A>().Where<A>(a => a.DataFields
.Any(b => b.Id == 1));
I'd also suggest that you change the parameter name from "where" to something like "whereExpression" or "predicate". Some sort of noun, anyway :)
Not quite sure if this is the proper solution or not. The problem feels like a bug and my solution like a workaround. Nonetheless the following works for me, which boils down to creating a 'copy' of the given expression by using its body and parameter to construct a new expression.
private void GetAsWhereB(Func<B, bool> where)
{
Expression<Func<T, bool>> w = Expression.Lambda<Func<T, bool>>(where.Body, where.Parameters);
using (ISession session = sessionFactory.OpenSession())
{
var records = session.Query<A>()
.Where(a => a.DataFields
.Any(w));
Console.Write("Number of records is {0}", records.Count());
}
}
I am confused on how can I use generic methods to parse generic list into datatable/dataset. My setup:
1. I have a class Customers defined in WCF Service Library.
namespace Wcf.Sample.ServiceLibrary
{
public class Customers
{
public string ID = string.Empty;
public string CompanyName = string.Empty;
public string ContactName = string.Empty;
}
}
2. I use this class to return a generic list from my OperationContract.
namespace Wcf.Sample.ServiceLibrary
{
[ServiceContract]
public interface ICustomerService
{
[OperationContract]
List<Customers> GetAllCustomers();
}
}
3. Consume WCF Service in web client page. On button click I populate the GridView with the list returned from GetAllCustomers(). This works perfectly fine.
GridView1.DataSource = client.GetAllCustomers();
GridView1.DataBind();
4. Now the issue is, for some reason (sort/paging function) I want to actually convert the returned generic list into a datatable. To do so, I have a method that returns me a datatable which I want to bind to a GridView. Here are the methods:
public static DataTable ConvertTo<T>(System.Collections.Generic.List<T> genericList)
{
//create DataTable Structure
DataTable dataTable = CreateTable<T>();
Type entType = typeof(T);
PropertyDescriptorCollection properties = TypeDescriptor.GetProperties(entType);
//get the list item and add into the list
foreach (T item in genericList)
{
DataRow row = dataTable.NewRow();
foreach (PropertyDescriptor prop in properties)
{
row[prop.Name] = prop.GetValue(item);
}
dataTable.Rows.Add(row);
}
return dataTable;
}
public static DataTable CreateTable<T>()
{
//T –> ClassName
Type entType = typeof(T);
//set the datatable name as class name
DataTable dataTable = new DataTable(entType.Name);
//get the property list
PropertyDescriptorCollection properties = TypeDescriptor.GetProperties(entType);
foreach (PropertyDescriptor prop in properties)
{
//add property as column
dataTable.Columns.Add(prop.Name, prop.PropertyType);
}
return dataTable;
}
I am not sure how to call this function? How can I specify the as Customers class which is actually in a webservice? Totally lost. I would appreciate if someone can guide me on the following code, how to make it work.
GridView1.DataSource = ConvertTo<???>(client.GetAllCustomers());
I was able to resolve this issue by modifing the WCF Service itself (although I was reluctant to do so). I modified the GetAllCustomers method to return a datatable instead of generic type. In the service itself, I am converting the generic type into datatable using the same methods:
public static DataTable ConvertTo<T>(System.Collections.Generic.List<T> genericList)
{
//create DataTable Structure
DataTable dataTable = CreateTable<T>();
Type entType = typeof(T);
PropertyDescriptorCollection properties = TypeDescriptor.GetProperties(entType);
//get the list item and add into the list
foreach (T item in genericList)
{
DataRow row = dataTable.NewRow();
foreach (PropertyDescriptor prop in properties)
{
row[prop.Name] = prop.GetValue(item);
}
dataTable.Rows.Add(row);
}
return dataTable;
}
public static DataTable CreateTable<T>()
{
//T –> ClassName
Type entType = typeof(T);
//set the datatable name as class name
DataTable dataTable = new DataTable(entType.Name);
//get the property list
PropertyDescriptorCollection properties = TypeDescriptor.GetProperties(entType);
foreach (PropertyDescriptor prop in properties)
{
//add property as column
dataTable.Columns.Add(prop.Name, prop.PropertyType);
}
return dataTable;
}
Another thing that I noticed is that the following line
PropertyDescriptorCollection properties = TypeDescriptor.GetProperties(entType);
would always returned null for my type. This was due to the fact that I didn't have any get/set methods in Customers class. I created get/set methods in Customer class and everything worked like a charm.
Thanks to everyone who helped and those who tried to help :)