ASP.NET

HOW to Use DROOLS with Dotnet MVC

21-Jul-16 22:33

That's called a cascading dropdown, so google "asp.net cascading dropdown" and you'll find various examples.

Member 616257721-Jul-16 1:51

Member 6162577

21-Jul-16 1:51

Hi
I am new in DROOLs pls provide me some sample how Drools implemented with MVC Dot Net

Thanks

Re: HOW to Use DROOLS with Dotnet MVC

F-ES Sitecore21-Jul-16 4:00

Re: MVC Controller Question

21-Jul-16 4:00

All someone is going to do is google "asp.net drools getting started" and post come links from the results, so you might as well just do the search yourself.

MVC Controller Question

TheOnlyRealTodd19-Jul-16 18:19

TheOnlyRealTodd

19-Jul-16 18:19

I've spent many, many hours toiling through learning ASP.NET MVC. The good news is, I actually understand most of it. However, there's one thing I'm not making a connection on.

I have a simple view called Customers which just shows a table with customer names and their membership types. I discovered that in the CustomerController, if I do not put this line of code in (in bold), my view cannot access the Membershiptype.Name field:

public ViewResult Index()
        {
            //Without the Include method below, the MembershipType would be null when the page loads, causing an error.
            var customers = _context.Customers.Include(c => c.MembershipType).ToList(); 
            
            return View(customers);
        }

However, I don't have to put a specific Include() in there to access customer.Name. See Customer View code below:

@foreach (var customer in Model)
        {
            <tr>
                <td>@Html.ActionLink(customer.Name, "Details", "Customers", new {id = customer.Id}, null)</td>

<td>@customer.MembershipType.Name</td>
          </tr>
      }

In this example, I had to add the

Include(c => c.MembershipType).

into the chain to access customer.MembershipType.Name from within the View, but there is not a

Include(c => c.Name)

needed in order to access customer.Name. Why is this? What exactly is this Include method doing? Thanks.

F-ES Sitecore20-Jul-16 0:13

Re: MVC Controller Question

20-Jul-16 0:13

This isn't an MVC question but an Entity Framework one (I assume _context is an Entity Framework database context).

If you have data in two tables like

SQL

MembershipType
--------------
MembershipTypeID, Type
1, Basic
2, Full

Customer
--------
CustomerID, Name, MembershipTypeID
1, John, 1
2, Dave, 1

These two tables relate on the MemebrshipTypeID, but they are part of different entities (each table is an entity). In EF when you ask for Customer entities;

_content.Customers.FirstOrDefault().Name

all it is doing is loading the data from the Customer table so you can only reference things in that table. However as the tables are related, your Customer class will have a MembershipType property too that will hold the data from MembershipType. By default this data isn't loaded though, so this

_content.Customers.FirstOrDefault().MembeshipType

will be null, so this

_content.Customers.FirstOrDefault().MembeshipType.Type

will throw a null reference extension. When accessing data you can tell EF to load related tables too by using Include

_content.Customers.Include("MembeshipType").FirstOrDefault().MembeshipType.Type

this will now work as when Customers is loaded, EF also loads the data from the related MembershipType table too and you can access properties from that entity.

TheOnlyRealTodd22-Jul-16 16:57

TheOnlyRealTodd

22-Jul-16 16:57

Awesome, thank you! Makes a lot of sense now!

MVC Model Binding

MadDashCoder19-Jul-16 6:31

19-Jul-16 6:31

I am trying to understand how MVC Model Binding works so that I can switch from using a Textbox to using a Dropdownlistbox.

In my Edit View I have a form that allows users to Edit a product after modifying its Name, Price, and CategoryId.

The Merchandise's CategoryID is the Primary Key in the Categories table and a Foreign Key in the Merchandise table in the database.

Instead of making users enter a number for the CategoryID I want them to select a CategoryName from a Dropdownlistbox. Once a CategoryName in the Dropdownlistbox is selected the CategoryID is selected automatically.

I have tried to use the following code in my ProductController but it is not working.

HTML

[HttpGet]
public ActionResult Edit(string id)
{
 MerchandiseServiceClient msc = new MerchandiseServiceClient();            
 MerchandiseViewModel mvm = new MerchandiseViewModel();
 mvm.Merchandise = msc.FindMerchandiseByID(id);
 ViewBag.CategoryList = new SelectList(msc.FindAllCategories(), "ID", "Name");

     return View("Edit", mvm);   
}

[HttpPost]
public ActionResult Edit(MerchandiseViewModel mvm)
{
  MerchandiseServiceClient msc = new MerchandiseServiceClient();            
  msc.EditMerchandise(mvm.Merchandise);           
     return RedirectToAction("Index");
}
 
// --------------Edit View-------------------------------------
 <tr>  
   <td>@Html.LabelFor(model=>model.Category.ID, "Category")</td> 
   <td> @Html.DropDownList("CategoryList", "Select Category")</td>    
</tr>

How can I change my code above to use the dropdownlistbox?

modified 19-Jul-16 13:21pm.

Richard Deeming19-Jul-16 8:01

Richard Deeming

19-Jul-16 8:01

Did you try my suggestion from your previous thread?
Re: Switching From Textbox To Dropdownlistbox - ASP.NET Discussion Boards[^]

"These people looked deep within my soul and assigned me a number based on the order in which I joined."
- Homer

MadDashCoder19-Jul-16 19:47

19-Jul-16 19:47

Hi, thank you for replying. You suggested that I change my code from

@Html.DropDownList("CategoryList", "Select Category")

@Html.DropDownListFor(model => model.Category.ID, ViewBag.CategoryList, "Select A Category")

I got the error has no applicable method named 'DropDownListFor' but appears to have an extension method by that name. So I changed the code to

@Html.DropDownListFor(model => model.Category.ID, (SelectList)ViewBag.listProducts, "Select A Category")

But now I get the error There is no ViewData item of type 'IEnumerable<SelectListItem>' that has the key 'Category.ID'.

F-ES Sitecore20-Jul-16 0:01

20-Jul-16 0:01

In order to get your code working as it is you need a CategoryList property on your model

public class MerchandiseViewModel
{
    public int CategoryList { get; set; }
}

To use DropDownListFor;

public class MerchandiseViewModel
{
    public Category Category { get; set; }
}

public ActionResult Test()
{
    List<Category> cats = new List<Category>();
    cats.Add(new Category { ID = 1, Name = "Category 1" });
    cats.Add(new Category { ID = 2, Name = "Category 2" });
    cats.Add(new Category { ID = 3, Name = "Category 3" });

    ViewBag.CategoryList = cats;

    return View();
}

[HttpPost]
public ActionResult Test(MerchandiseViewModel mvm)
{
    List<Category> cats = new List<Category>();
    cats.Add(new Category { ID = 1, Name = "Category 1" });
    cats.Add(new Category { ID = 2, Name = "Category 2" });
    cats.Add(new Category { ID = 3, Name = "Category 3" });

    ViewBag.CategoryList = cats;

    return View(mvm);
}

view;

@using (Html.BeginForm())
{
    <p>
        @Html.DropDownListFor(m => m.Category.ID, new SelectList(ViewBag.CategoryList, "ID", "Name"), "Select a category")
    </p>
    <p>
        <input type="submit" value="Submit"/>
    </p>
}

Note I put the categories in the ViewBag and do the convert to SelectList in the view, that just means that if you want to use the categoires elsewhere on the view you still can.

MadDashCoder20-Jul-16 7:12

20-Jul-16 7:12

Thank you so much for replying. I see what you are trying to do, unfortunately its not working for me since my situation is a little different than what you've posted above.

Below is a snippet of the MerchandiseServiceClient class definition inside of the Models folder

public class MerchandiseServiceClient
{
       private string BaseURL = "http://localhost:14000/MerchandiseService.svc/";
       public Merchandise FindMerchandiseByID(string id)
       {
           try
           {
               var webClient = new WebClient();
               string url = string.Format(BaseURL + "FindMerchandiseByID/{0}", id);
               var javascriptSerializer = new JavaScriptSerializer();
               return javascriptserializer.Deserialize<Merchandise>(jsn);
           }
           catch
           {
               return null;
           }
       }

       public List<Category> FindAllCategories()
       {
           try
           {
               var webClient = new WebClient();
               var jsn = webClient.DownloadString(BaseURL + "FindAllCategories");
               var javascriptSerializer = new JavaScriptSerializer();
               return javascriptSerializer.Deserialize<List<Category>>(jsn);
           }
           catch
           {
               return null;
           }
       }
       .
       .
       .
       .
}

The MerchandiseServiceClient class is one of many classes in the Models folder. The FindAllCategories() method of the MerchandiseServiceClient class gets JSON data from a RESTful WCF service and it returns a List of Category objects.

I tried to use this List of Category objects to populate the dropdownlist but it is not working. Please see my code below.

MerchandiseController

[HttpGet]
public ActionResult Edit(string id)
{
  MerchandiseServiceClient msc = new MerchandiseServiceClient();  
  ViewBag.categoryList = msc.FindAllCategories();
          
  MerchandiseViewModel mvm = new MerchandiseViewModel();
  mvm.Merchandise = msc.FindMerchandiseByID(id);
            
  return View("Edit", mvm);   
}

Edit View

<tr>
 <td>@Html.LabelFor(model=>model.Category.ID, "Category")</td>
 <td> @Html.DropDownListFor(model => model.Category.ID, (SelectList)ViewBag.categoryList, "Select A Category")</td>  
</tr>

modified 21-Jul-16 11:35am.

F-ES Sitecore20-Jul-16 22:10

20-Jul-16 22:10

@Html.DropDownListFor(model => model.Category.ID, (SelectList)ViewBag.categoryList, "Select A Category")</

In the above ViewBag.categoryList can't be cast to SelectList as it isn't of that type and can't be converted to that type. You need something similar to my posted code

@Html.DropDownListFor(m => m.Category.ID, new SelectList(ViewBag.categoryList, "ID", "Name"), "Select a category")

Replace "ID" and "Name" with the properties on the Category class that you want to be used for the value and the text.

jkirkerx3-Aug-16 8:01

jkirkerx

3-Aug-16 8:01

Well I'm late to the party here, but since I'm trying to fix my VS2015 SP3 problem here, and waiting for the VS2015 with SP3 to load, I'll throw in my 2 cents.

I found it best to create a

Dictionary<string, string> Categories { get; set; }

So if you have a model

public class model_items
{
  int ID { get; set; }
  string SKU { get; set; }
  int CategoryID { get; set; }

  Dictionary<string, string> select_Categories { get; set; }
}

This like FSSiteCore said, you use his example in the View

@Html.DropDownFor(m => m.CategoryID, new SelectList(@Model.selectCategory), "-- Select Category --")

To populate the model in the controller

model_items model = new model_items();
model = load_items(1);
model.selectCategories = load_Categories();

Then you write a function that loads a Dictionary of string string. You can write a function using EF to load the Category Key and value, and then package those as a Dictionary.

I have found this to be the best way to do it for me so far, being on my 3rd MVC project now.
Reason being is well the SelectList in Razor likes Dictionaries and takes them well with no problems.

Message Closed

18-Jul-16 14:50