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.
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've been trying to experiment with model binding to make our API easier to use. When using the API I can't get the model binding to bind when the data is in the body, only when it is part of the query.
The code I have is:
public class FunkyModelBinder : IModelBinder
{
public bool BindModel(HttpActionContext actionContext, ModelBindingContext bindingContext)
{
var model = (Funky) bindingContext.Model ?? new Funky();
var hasPrefix = bindingContext.ValueProvider
.ContainsPrefix(bindingContext.ModelName);
var searchPrefix = (hasPrefix) ? bindingContext.ModelName + "." : "";
model.Funk = GetValue(bindingContext, searchPrefix, "Funk");
bindingContext.Model = model;
return true;
}
private string GetValue(ModelBindingContext context, string prefix, string key)
{
var result = context.ValueProvider.GetValue(prefix + key);
return result == null ? null : result.AttemptedValue;
}
}
When looking at the ValueProvider property on the bindingContext I only see QueryStringValueProvider and RouteDataValueProvider which I think means that if the data is in the body I won't get it. How should I do this? I would like to support posting data as either json or form-encoded.
I am looking into this as well.
WebApis Model Binder comes with two built in ValueProviders.
QueryStringValueProviderFactory & RouteDataValueProviderFactory
Which are searched when you call
context.ValueProvider.GetValue
This question has some code on how to bind data from the body.
how to pass the result model object out of System.Web.Http.ModelBinding.IModelBinder. BindModel?
You could create a custom ValueProvider to do this as well, probably a better idea - which will be searched for the value matching the key. The above link just does this within the model binder, which limits the ModelBinder to looking only in the body.
public class FormBodyValueProvider : IValueProvider
{
private string body;
public FormBodyValueProvider ( HttpActionContext actionContext )
{
if ( actionContext == null ) {
throw new ArgumentNullException( "actionContext" );
}
//List out all Form Body Values
body = actionContext.Request.Content.ReadAsStringAsync().Result;
}
// Implement Interface and use code to read the body
// and find your Value matching your Key
}
I have code like this:
//Fields
Product _prod, _existingProd;
void Test()
{
_prod = MakeAndPopulateSomeRandomProduct();
_existingProd = GetProdFromDb(1);
Mapper.CreateMap()
.AfterMap((s, d) =>
{
Console.WriteLine(d==_existingProd); //Why does this print false?
//Customize other properties on destination object
});
Mapper.Map(_prod, _existingProd);
}
When I call Test(), false is printed but I expected true. In my scenario, it is important to be able to access the original destination object via the AfterMap argument. I only included the fields to demonstrate the problem but in my real code, I don't have direct access to them. How can I access the object instances passed in to Map() when customizing the mapping?
The following example works. Probably you are using some type converter which creates new instance... Also please provide all mapping configurations to better understand the problem.
[TestFixture]
public class AfterMap_Test
{
//Fields
private Product _prod, _existingProd;
[Test]
public void Test()
{
Mapper.CreateMap<Product, Product>()
.AfterMap((s, d) =>
{
Trace.WriteLine(d == _existingProd); //Why does this print false?
//Customize other properties on destination object
});
_existingProd = new Product {P1 = "Destination"};
_prod = new Product {P1 = "Source"};
Mapper.Map(_prod, _existingProd);
}
}
internal class Product
{
public string P1 { get; set; }
}
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 think I've established that in as3corelib JSON.decode I have no choice but to deserialise to a plain old flex object.
var data:Object = JSON.decode(json);
If I then want to get the data contained in the object into another type I can't use type casting. I have to instantiate a new instance and add the properties manually.
var data:Object = JSON.decode(json);
var model:Model = new Model();
model.name = data.name;
model.notes = data.notes;
A pain and a bit ugly, but I'm guessing this is the price to be paid for going from untyped json to a flex type. My first question is whether my assumption is correct and there is no prettier way to create my model instance with the data contained within the json?
My second question, if so then before I write my own method to do this, is there anything inside the flex api that will take the data object and mixin it's values to my model instance?
Cheers,
Chris
the approach I've always used proved to be part of the AMF3 serialization mechanism in ActionScript.
have a look at IExternalizable and registerClassAlias.
now what I use is the following:
interface ISerializable {
public function getRawData():Object;
public function setRawData(param:Object):void;
}
function registerType(id:String, type:Class):void {
//implementation
}
function getTypeByID(id:String):Class {
//implementation
}
function getTypeID(type:Class):String {
//implementation
}
and to the decoder/encoder you register a class alias.
serialization of an object works as follows:
var raw:Object = model.getRawData();
raw[" type"] = getTypeID(model);
var encoded:String = JSON.encode(raw);
decoding works as follows:
var raw:Object = JSON.decode(raw);
var cl:Class = getTypeByID(raw[" type"]);
if (cl == null) throw new Error("no class registered for type: "+raw[" type"]);
delete raw[" type"];
var model:ISerializable = new cl();
model.setRawData(raw);
you will need to do this recursively on the whole deserialized JSON tree, starting at the leafs.
For cyclic reference, you'll need a trick.
I had an implementation of this somewhere, but I can't find it.
You can loop within the field of you json decoded object and assign them into your model:
function json2model(json:String):Model{
var data:Object = JSON.decode(json);
var m:Model=new Model();
for (var field:String in data) {
if (m.hasOwnProperty(field)) {
m[field] = data[field];
}
}
return m;
}
var model:Model=json2model(json)
or add a static function within your Model if you preffer:
public class Model {
//...
public static function fromJSon(json:String):Model {
var data:Object = JSON.decode(json);
var m:Model=new Model();
for (var field:String in data) {
if (m.hasOwnProperty(field)) {
m[field] = data[field];
}
}
return m;
}
}
}
var model:Model=Model.fromJSon(json);