new to C# and MVC. What I would like to achieve is passing a variable as ViewData from one view to another view without using ID in the ActionResult because this view generates it own variable. I am sure there are better ways to do that, but here what I thought might work.
First I made a model:
public class EventToShow
{
public Int64? ID { get; set; }
public Int64? EventID { get; set; }
}
Then I passed the variable EventID from the first View (Telerik MVC GRID) using the following:
columns.Template(item => Html.Raw(string.Format("{1}", Url.Action("tableread", "Home", new { id = (long)item.Event_ID }), "EventID"))).Width(20);
It worked using the following in my controller:
[AcceptVerbs(HttpVerbs.Post)]
public ActionResult tableread1(long? id)
{
ViewData["EID"] = id;
EventToShow ctx = new EventToShow();
ctx.ID = 1;
ctx.EventID = (long)ViewData["EID"];
return RedirectToAction("EditServerSide");
}
To pass the variable to the other view I tried to use the following (I think it is very wrong):
public ActionResult EditServerSide()
{
EventToShow ctx = new EventToShow();
var model1 = ctx.(x => x.ID == 1); **// The error here is (Identifier** expected)
ViewData["EID"] = ctx.EventID;
var model = from o in new Main().OffLinePayments
select new EditOffLinePayment
{
ID = o.ID,
Amount = o.Amount,
Details = o.Details
};
return View(model, ViewData["EID"]) **(this must be wrong)**
}
I thought maybe I should make the variable like this:
private string GetFullName()
{
EventToShow ctx = new EventToShow();
var name = EventToShow().Where(x => x.ID == 1);
ViewData["EID"] = ctx.EventID;
return name;
}
First I got an error: ‘GridEdit_OfflinePayment.Models.EventToShow' is a 'type' but is used like a 'variable'
I also did not know how to incorporate returned [name] in the EditServerSide Action.
My question, is there a better way to achieve what I am trying to do, and if this approach is correct, I would appreciate any help to fix these errors
From what I understand of the question is that you would like to pass data between several Actions? Like some sort of wizard steps process where you can pass data between multiple Actions?
If that's the case then here are some related questions and their answers:
How do I pass data across ActionResults in MVC 3?
multi-step registration process issues in asp.net mvc (splitted viewmodels, single model)
Related
I am new to ASP.NET MVC and I am stuck on a point. I am working on a classified site. My situation is, I have a lot of categories in which a user can post their ads and each ad category have different View. I have created a Controller Action like
public ActionResult PostAd(string CategoryName, string SubCategoryName)
{
if(categoryName == "Vehicle" && SubCategoryName == "Cars")
{
var model = new CarAdViewModel();
// set CarAdViewModel properties...
return View("CarAdCreateView", model);
}
else if(categoryName == "Vehicle" && SubCategoryName == "Bikes")
{
var model = new BikeAdViewModel();
// set BikeAdViewModel properties...
return View("BikeAdViewModel", model);
}
else if(categoryName == "Property" && SubCategoryName == "RentHouse")
{
var model = new RentHouseAdViewModel();
// set RentHouseAdViewModel properties...
return View("RentHouseAdViewModel", model);
}
else................... so on and so on
}
My problem is I have huge number of Categories and Sub Categories almost 60+. And if I keep on coding like above for 60+ categories and subcategories, my PostAd method is going to blast and become unmanageable.
Please tell me some best practice or pattern which can bring me out of this problem.
Unfortunately, some of what you are doing cannot be avoided. There needs to be some form of model and view selection based on category.
Use a factory pattern. Create a base class:
public abstract class BaseCategory
{
public abstract string GetViewName();
public abstract Object CreateModelFromFormData();
}
For each category, create a sub-class derived from BaseCategory and implement the abstract functions.
In your action, do the following:
public ActionResult PostAd(string categoryName, string subCategoryName)
{
BaseFactory factory;
if (categoryName == "Vehicle")
{
if (subCategoryName == "Cars")
{
factory = new CarsFactory();
}
else ...
}
else ...
return View(factory.GetViewName(), factory.CreateModelFromFormData());
}
I have a couple reasons for this schema:
I am purposefully using if/else for the factory selection. Your controller is going to be created and re-created for every action call. So pre-populating a list will constantly and needlessly create objects for categories that will not be selected. A simple if/else will be more efficient. If you want to prevent the if/else, you can put your factories in a Dictionary and select based on the categories, but that would be a lot of needless constructor actions.
I made the CreateModelFromFormData a function because I assume you'll need to copy data from the posted form data. This may require passing in data, but I left the function parameterless.
I used base/derived classes because the copying of the form data will probably need to be custom from the model being created and the form data being posted. Also, saving to persistent storage (file or database) may be category-specific as well.
It would be one of some possible solutions
public class PostAdData
{
public string CategoryName;
public string SubCategoryName;
public string ViewName;
public Type Model;
}
public class PostController : Controller
{
private readonly List<PostAdData> _theData;
public HomeController()
{
_theData = InitializeData();
}
public ActionResult PostAd(string categoryName, string subCategoryName)
{
var data = _theData.FirstOrDefault(c => c.CategoryName == categoryName && c.SubCategoryName == subCategoryName);
if (data != null)
{
var model = Activator.CreateInstance(data.Model);
return View(data.ViewName, model);
}
return View("Error");
}
[NonAction]
public List<PostAdData> InitializeData()
{
var result = new List<PostAdData>
{
new PostAdData
{
CategoryName = "Vehicle",
SubCategoryName = "Cars",
ViewName = "CarAdCreateView",
Model = typeof (CarAdViewModel)
}
};
return result;
}
}
You should make this data driven. You create a lookup table that has a compound primary key of category and subcategory. Then it has a table with View in it. Then you simply ad rows for each category/subcategory/view combination.
If you absolutely don't want a database, then you can use a simple hashset or dictionary.
var views = new Dictionary<Tuple<string,string>,string>();
views.Add(new Tuple<string,string>("Vehicle", "Cars"), "CarAdCreateView");
Then in your PostAd you just lookup the correct view.
What a beautiful solution on www.asp.net to my question, here is the link : http://forums.asp.net/t/1923868.aspx/1?ASP+NET+MVC+Conditional+ViewModel+Abstraction
Edit:
My code is :
public class AdsController : Controller
{
private readonly IAdService _adService;
public AdsController(IAdService adService)
{
_adService = adService;
}
public ActionResult PostAd(string Category, string SubCategory)
{
//Here I will call
var strategy = GetStrategy(CategoryName, SubCategoryName);
strategy.FillModel(_adService );
return View(strategy.ViewName, strategy.Model);
}
}
I'm very new to ASP.NET, but I know a little programming in Java. I want to use a ZIP code to query a database which will return a string, then use that string to query another database. I wanted to do this on the same control model. I thought it would be easy, and it sounds pretty easy.
When I created the controller, I put the model class of the first database, and, so far, I've gotten as far as querying the first database, but now that I have the string I want to query a second database through the DBEntities.
This displays an error saying:
> The model item passed into the dictionary is of type
> 'System.Collections.Generic.List`1[FinalBallot.Models.AgainCandidate]',
> but this dictionary requires a model item of type
> 'System.Collections.Generic.IEnumerable`1[FinalBallot.Models.ZipTable]'.
Is there a way to solve this in an easy way?
public class Default1Controller : Controller
{
private CandidatesDBEntities db = new CandidatesDBEntities();
public string districString = "";
//
// GET: /Default1/
public ViewResult Index(string searchString)
{
var queryZip = from s in db.ZipTables select s;
var queryCandidates = from s1 in db.AgainCandidates select s1;
double sT = 0;
//method so it doesnt display the whole db
if (String.IsNullOrEmpty(searchString))
{
queryZip = queryZip.Where(s => s.ZipL.Equals(0));
}
if (!String.IsNullOrEmpty(searchString))
{
sT = double.Parse(searchString);
queryZip = queryZip.Where(s => s.ZipL.Equals(sT));
try
{
districString = queryZip.ToList().ElementAt(0).District;
}
catch
{
}
if (!String.IsNullOrEmpty(districString))
{
queryCandidates = queryCandidates.Where(s1 => s1.District.Equals(districString));
}
}
return View(queryCandidates.ToList());
}
In your view, did you specify the model to be IEnumerable<ZipTable>? The model that you're passing to your view is IEnumerable<AgainCandidate>, so you would get an error if you specified your model as something else. You'd need to change the model in your view to be IEnumerable<AgainCandidate>.
UPDATE:
Based on your revised explanation, you can do a couple things:
1) create a "ViewModel" that has two properties for each of your collections you want to display on the page like so:
public class MyViewModel
{
IEnumerable<ZipTable> Zips { get; set; }
IEnumerable<AgainCandidate> Candidates { get; set; }
}
Instantiate that in your action method and return that as your model. This would be my preferred approach.
2) Stash your two collections in the ViewData bag in your action method:
ViewData["Zips"] = queryZip.ToList();
ViewData["Candidates"] = queryCandidates.ToList();
return View(ViewData);
You can pull this data in your view like this:
#foreach (var zip in ViewData["Zips"] as IEnumerable<ZipTable>)
{
...
}
I'm trying to select all the rows out of a database using entity framework for manipulation before they're sent to the form
var ptx = [modelname].[tablename]();
ptx.[tablename].Select(????)
what goes in the ????
I used the entitydatasource and it provide everything I needed for what I wanted to do.
_repository.[tablename].ToList();
Entity Framework has one beautiful thing for it, like :
var users = context.Users;
This will select all rows in Table User, then you can use your .ToList() etc.
For newbies to Entity Framework, it is like :
PortalEntities context = new PortalEntities();
var users = context.Users;
This will select all rows in Table User
How about:
using (ModelName context = new ModelName())
{
var ptx = (from r in context.TableName select r);
}
ModelName is the class auto-generated by the designer, which inherits from ObjectContext.
You can use this code to select all rows :
C# :
var allStudents = [modelname].[tablename].Select(x => x).ToList();
You can simply iterate through the DbSet context.tablename
foreach(var row in context.tablename)
Console.WriteLn(row.field);
or to evaluate immediately into your own list
var allRows = context.tablename.ToList();
If it's under a async method then use ToListAsync()
public async Task<List<DocumentTypes>> GetAllDocumentTypes()
{
var documentTypes = await _context.DocumentTypes.ToListAsync();
return documentTypes;
}
Old post I know, but using Select(x => x) can be useful to split the EF Core (or even just Linq) expression up into a query builder.
This is handy for adding dynamic conditions.
For example:
public async Task<User> GetUser(Guid userId, string userGroup, bool noTracking = false)
{
IQueryable<User> queryable = _context.Users.Select(x => x);
if(!string.IsNullOrEmpty(userGroup))
queryable = queryable.Where(x => x.UserGroup == userGroup);
if(noTracking)
queryable = queryable.AsNoTracking();
return await queryable.FirstOrDefaultAsync(x => x.userId == userId);
}
Here is a few ways to do it (Just assume I'm using Dependency Injection for the DbConext)
public class Example
{
private readonly DbContext Context;
public Example(DbContext context)
{
Context = context;
}
public DbSetSampleOne[] DbSamples { get; set; }
public void ExampleMethod DoSomething()
{
// Example 1: This will select everything from the entity you want to select
DbSamples = Context.DbSetSampleOne.ToArray();
// Example 2: If you want to apply some filtering use the following example
DbSamples = Context.DbSetSampleOne.ToArray().Where(p => p.Field.Equals("some filter"))
}
You can use:
ptx.[tablename].Select( o => true)
I am trying to pass a variable from a method in my Controller to a method in a Model. Since the method in the Model takes one argument (which was designed earlier), I cannot pass my variable as an argument to the method in the Model. And also, the method in this Model is called by other controllers too, so if I change the argument, I have to change all the controllers too, which would be a tedious task.
What I have been trying so far is- I created one MyVariableClass and declared a property. Then I instantiated that class and set the property string to the variable that I wanted to pass. Now, in my Model's method, I instantiated the same MyVariableClass again, but when I did that, the value of the variable was set to null. The code I have right now is -
public ActionResult ItemInformation( string id)
{
//Pass a string to MyVariable
MyVariableVClass params = new MyVariableClass();
params.myVariable = "abc";
//This is what My Model is taking as an argument(id), and I don't want to
//pass mYvariable along with that argument because it will break other controllers
// too which calls this method
var itemInformation = _repository.GetItemInformation(id);
return View(itemInformation);
}
and MyVariableClass
public class MyVariableClass
{
public string myVariable { get; set; }
}
and the method in My Model
public IList<Items> GetItemInformation(string itemId)
{
MyVariableClass webType = new MyVariableClass();
var _params = webType.myVariable;
//Check this variable and perform database query
if (_params =="this")
{
var query = myFirstQuery;
}
else
{
var query = mySecondQuery;
}
//return ....
}
Anybody has solution to this? Thanks in Advance!
Any reason why subclassing your model and overriding the GetItemInformation method wouldn't work? Or, even easier, why not just overload the GetItemInformation method with one that takes two strings? Your other controllers can still use the one that only takes a single string.
public IList<Items> GetItemInformation(string itemId, MyVariableClass webType)
{
var _params = webType.myVariable;
//Check this variable and perform database query
if (_params == "this")
{
var query = myFirstQuery;
}
else
{
var query = mySecondQuery;
}
//return ....
}
public IList<Items> GetItemInformation(string itemId)
{
MyVariableClass fauxType = new MyVariableClass();
fauxType.myVariable = "not this";
return GetItemInformation(itemId, fauxType);
}
Try using session variable.
Can I convert a IQueryable result to a injected object on the fly?
I know I can do this with the help of Valueinjecter:
usercategory uc1 = new usercategory(example);
usercategoryViewData ucVD1 = new usercategoryViewData();
ucVD1.injectFrom(uc1);
So instead of this:
from u in db.usercategories
where u.id==id
select new usercategoryViewModel {id = u.id, name = u.id, description = u.id};
I would like to use something like:
from u in db.usercategories
where u.id==id
select new usercategoryViewModel.InjectFrom(u);
The other alternative I have atm is to loop through a IEnumerable and create one with injected objects instead.
here I show 2 ways of doing this:
public class Foo
{
public string Name { get; set; }
}
[Test]
public void TestMethod1()
{
var bars = new[] { new { Name = "aaa" }, new { Name = "bbb" } };
IEnumerable<Foo> foos = bars.Select(o => new Foo().InjectFrom(o)).Cast<Foo>();
IEnumerable<Foo> foos2 = from bar in bars
select new Foo().InjectFrom(bar) as Foo;
Assert.AreEqual(bars.First().Name, foos.First().Name);
Assert.AreEqual(bars.First().Name, foos2.First().Name);
}
Whilst that might be possible, if there's any complexity in u then I think it's a bad idea.
At some point the ORM you're using (Linq-to-SQL? EF?) needs to switch from executing on the database to executing in .NET. At that boundary it needs to work out what data it needs from the database. In the first example, that's completely clear: it only needs u.id. In the second it has no idea: it doesn't know what properties InjectFrom will read from it, so it will need to load all the values from the UserCategories table, and maybe related objects too, just in case.