I have:
Function SaveAnswers(ByVal collection As FormCollection) As ActionResult
End Funciton
And I want to turn collection to JSON, I thought there was a serializer to do this but can't seem to find it?
Serialising a FormCollection object did not work for me, the keys serialized, but the values didn't.
I wanted to use an easy way to 'record' the FormCollection values to reuse in test cases. For this purpose, I created an extension method:
public static string ToJSON(this System.Web.Mvc.FormCollection collection)
{
var list = new Dictionary<string, string>();
foreach (string key in collection.Keys)
{
list.Add(key, collection[key]);
}
return new System.Web.Script.Serialization.JavaScriptSerializer().Serialize(list);
}
There is. In c#:
return Json(object/array/whatever);
It returns a JsonResult, which is an ActionResult, so it "fits" into your function as it exists already.
James
Related
Is there a way to pass this javascript object
Object { 35=true, 179=true, 181=true}
into a controller action as
Dictionary<int, bool>
I've checked the following methods:
var remoteUrl = "#Url.Action("UpdateProjectStructureSelection")" + "?tlpId=#Model.TopLevelProjectId";
$.post(remoteUrl, mapSiteSelectionChoices, function(callbackResult) {
alert(callbackResult);
});
and
var remoteUrl = "#Url.Action("UpdateProjectStructureSelection")" + "?tlpId=#Model.TopLevelProjectId";
$.post(remoteUrl, { values : mapSiteSelectionChoices }, function(callbackResult) {
alert(callbackResult);
});
However in both cases
public ActionResult UpdateProjectStructureSelection(int tlpId, Dictionary<int, bool> values)
has been called, but values was empty.
Since i've transfered more complex types into a controller action without writing a custom model binder i've been wondering whether i'm just doing something wrong here.
Is a custom model binder the only way here to get it as dictionary? (other than using JsonConvert + stringify on clientside)
Addition (This works but i'd love to avoid extra code) :
public ActionResult UpdateProjectStructureSelection(int tlpId, string values)
{
var dict = JsonConvert.DeserializeObject<Dictionary<int, bool>>(values);
}
Not with the object in that format. It would need to be in the following format to be used by the DefaultModelBinder
var data = { 'dict[0].key': '35', 'dict[0].value': 'True', 'dict[1].key': '179', 'values[1].value': 'True', dict[0].key': '8', 'dict[0].value': 'True' };
$.post(remoteUrl, data, function(callbackResult) {
and the controller
public ActionResult UpdateProjectStructureSelection(Dictionary<int, bool> dict)
As you noted, another option is to use a custom ModelBinder, for example this answer
In the RedirectToAction below, I'd like to pass a viewmodel. How do I pass the model to the redirect?
I set a breakpoint to check the values of model to verify the model is created correctly. It is correct but the resulting view does not contain the values found in the model properties.
//
// model created up here...
//
return RedirectToAction("actionName", "controllerName", model);
ASP.NET MVC 4 RC
RedirectToAction returns a 302 response to the client browser and thus the browser will make a new GET request to the url in the location header value of the response came to the browser.
If you are trying to pass a simple lean-flat view model to the second action method, you can use this overload of the RedirectToAction method.
protected internal RedirectToRouteResult RedirectToAction(
string actionName,
string controllerName,
object routeValues
)
The RedirectToAction will convert the object passed(routeValues) to a query string and append that to the url(generated from the first 2 parameters we passed) and will embed the resulting url in the location header of the response.
Let's assume your view model is like this
public class StoreVm
{
public int StoreId { get; set; }
public string Name { get; set; }
public string Code { set; get; }
}
And you in your first action method, you can pass an object of this to the RedirectToAction method like this
var m = new Store { StoreId =101, Name = "Kroger", Code = "KRO"};
return RedirectToAction("Details","Store", m);
This code will send a 302 response to the browser with location header value as
Store/Details?StoreId=101&Name=Kroger&Code=KRO
Assuming your Details action method's parameter is of type StoreVm, the querystring param values will be properly mapped to the properties of the parameter.
public ActionResult Details(StoreVm model)
{
// model.Name & model.Id will have values mapped from the request querystring
// to do : Return something.
}
The above will work for passing small flat-lean view model. But if you want to pass a complex object, you should try to follow the PRG pattern.
PRG Pattern
PRG stands for POST - REDIRECT - GET. With this approach, you will issue a redirect response with a unique id in the querystring, using which the second GET action method can query the resource again and return something to the view.
int newStoreId=101;
return RedirectToAction("Details", "Store", new { storeId=newStoreId} );
This will create the url Store/Details?storeId=101
and in your Details GET action, using the storeId passed in, you will get/build the StoreVm object from somewhere (from a service or querying the database etc)
public ActionResult Details(string storeId)
{
// from the storeId value, get the entity/object/resource
var store = yourRepo.GetStore(storeId);
if(store!=null)
{
// Map the the view model
var storeVm = new StoreVm { Id=storeId, Name=store.Name,Code=store.Code};
return View(storeVm);
}
return View("StoreNotFound"); // view to render when we get invalid store id
}
TempData
Following the PRG pattern is a better solution to handle this use case. But if you don't want to do that and really want to pass some complex data across Stateless HTTP requests, you may use some temporary storage mechanism like TempData
TempData["NewCustomer"] = model;
return RedirectToAction("Index", "Users");
And read it in your GET Action method again.
public ActionResult Index()
{
var model=TempData["NewCustomer"] as Customer
return View(model);
}
TempData uses Session object behind the scene to store the data. But once the data is read the data is terminated.
Rachel has written a nice blog post explaining when to use TempData /ViewData. Worth to read.
Using TempData to pass model data to a redirect request in Asp.Net Core
In Asp.Net core, you cannot pass complex types in TempData. You can pass simple types like string, int, Guid etc.
If you absolutely want to pass a complex type object via TempData, you have 2 options.
1) Serialize your object to a string and pass that.
Here is a sample using Json.NET to serialize the object to a string
var s = Newtonsoft.Json.JsonConvert.SerializeObject(createUserVm);
TempData["newuser"] = s;
return RedirectToAction("Index", "Users");
Now in your Index action method, read this value from the TempData and deserialize it to your CreateUserViewModel class object.
public IActionResult Index()
{
if (TempData["newuser"] is string s)
{
var newUser = JsonConvert.DeserializeObject<CreateUserViewModel>(s);
// use newUser object now as needed
}
// to do : return something
}
2) Set a dictionary of simple types to TempData
var d = new Dictionary<string, string>
{
["FullName"] = rvm.FullName,
["Email"] = rvm.Email;
};
TempData["MyModelDict"] = d;
return RedirectToAction("Index", "Users");
and read it later
public IActionResult Index()
{
if (TempData["MyModelDict"] is Dictionary<string,string> dict)
{
var name = dict["Name"];
var email = dict["Email"];
}
// to do : return something
}
Another way to do it is to store it in the session.
var s = JsonConvert.SerializeObject(myView);
HttpContext.Session.SetString("myView", s);
and to get it back
string s = HttpContext.Session.GetString("myView");
myView = JsonConvert.DeserializeObject<MyView>(s);
I feel a bit absurd asking this but I can't find a way to get parameters for a get request at
/api/foo?sort=name for instance.
In the ApiController class, I gave a public string Get(). Putting Get(string sort) makes /api/foo a bad request. Request instance in the ApiController is of type System.Net.Http.HttpRequestMessage. It doesn't have a QueryString or Parameters property or anything.
The ApiController is designed to work without the HttpContext object (making it portable, and allowing it to be hosted outside of IIS).
You can still access the query string parameters, but it is done through the following property:
Request.GetQueryNameValuePairs()
Here's an example loop through all the values:
foreach (var parameter in Request.GetQueryNameValuePairs())
{
var key = parameter.Key;
var value = parameter.Value;
}
You could just use
HttpContext.Current.Request.QueryString
Here's an example that gets the querystring q from the request and uses it to query accounts:
var q = Request.GetQueryNameValuePairs().Where(nv => nv.Key =="q").Select(nv => nv.Value).FirstOrDefault();
if (q != null && q != string.Empty)
{
var result = accounts.Where(a=>a.Name.ToLower().StartsWith(q.ToLower()));
return result;
}
else
{
throw new Exception("Please specify a search query");
}
This can be called then like this:
url/api/Accounts?q=p
Get all querystring name/value pairs into a variable:
IEnumerable<KeyValuePair<string, string>> queryString = request.GetQueryNameValuePairs();
Then extract a specified querystring parameter
string value = queryString.Where(nv => nv.Key == "parameterNameGoesHere").Select(nv => nv.Value).FirstOrDefault();
You can also use the following
var value = request.GetQueryNameValuePairs().Where(m => m.Key == "paramName").SingleOrDefault().Value;
if we have a proper model for that request
for example
public class JustModel
{
public int Id {get;set;}
public int Age {gets;set;}
}
and query like this
/api/foo?id=1&Age=10
You could just use [FromUri] attribute
For example
public IHttpActionResult GetAge([FromUri] JustModel model){}
You're trying to build an OData webservice? If so, just return an IQueryable, and the Web API will do the rest.
Adding a default value does the job:
public string Get(string sort="")
I have added a key-value pair in the action result like this:
[HttpPost, Authorize]
public ActionResult ListFacilities(int countryid)
{
...
ModelState.AddModelError("Error","No facilities reported in this country!");
...
}
I have some cumbersome codes like these in a unit test to :
public void ShowFailforFacilities()
{
//bogus data
var facilities = controller.ListFacilities(1) as PartialViewResult;
Assert.AreSame("No facilities reported in this country!",
facilities.ViewData.ModelState["Error"].Errors.FirstOrDefault().ErrorMessage);
}
Of course, it works whenever I have only one error.
I don't like facilities.ViewData.ModelState["Error"].Errors.FirstOrDefault().ErrorMessage.
Is there an easier way for me to fetch the value from that dictionary?
Your FirstOrDefault isn't needed, because you'll get a NullReferenceException when accessing ErrorMessage. You can just use First().
Either way, I couldn't find any built-in solution. What I've done instead is create an extension method:
public static class ExtMethod
{
public static string GetErrorMessageForKey(this ModelStateDictionary dictionary, string key)
{
return dictionary[key].Errors.First().ErrorMessage;
}
}
Which works like this:
ModelState.GetErrorMessageForKey("error");
If you need better exception handling, or support for multiple errors, its easy to extend...
If you want this to be shorter you can create an extension method for the ViewData...
public static class ExtMethod
{
public static string GetModelStateError(this ViewDataDictionary viewData, string key)
{
return viewData.ModelState[key].Errors.First().ErrorMessage;
}
}
and usage:
ViewData.GetModelStateError("error");
Have you tried this?
// Note: In this example, "Error" is the name of your model property.
facilities.ViewData.ModelState["Error"].Value
facilities.ViewData.ModelState["Error"].Error
i have a dropdown list which select a value
[AcceptVerbs(HttpVerbs.Post)]
public ActionResult Screenname(FormCollection collection)
{
Viewdata["screenname"] = collection[0];
return RedirectToAction("Index", new { ScreenName = ViewData["screenname"] });
}
then i want to access this ViewData in other actions like this
[AcceptVerbs(HttpVerbs.Post)]
public ActionResult Create(FormCollection collection, string screenname)
{
try
{
/// thats my dataobject which creates
DataObj.SaveData(Guid.Empty, collection, screenname);
return RedirectToAction("Index", new { ScreenName = ViewData["screenname"] });
}
catch
{
return View("Error");
}
}
where index looks like this ...
public ActionResult Index(string ScreenName)
{
///thats my list
GetTable = new GetDataTable(ScreenName);
return View(GetTable);
}
First when i select the value and index gets executed properly.... but when i try to access the viewdata again it doesn't contain the value so anybody if please can help ...
or alternate method to save and retrieve data .
The ViewData object is specific for the particular action that is executing. To pass data between actions, use TempData. more on the difference between the two on MSDN.
You can also directly write to the session state through the Controller.Session property.
This has actually been covered quite often here. The solution for now is to use TempData to save the data you need before you use RedirectToAction().
If you do a search for "RedirectToAction" you'll find a number of posts covering this topic, such as this one.
The next official release of the framework will fix this.
I used a view to take the data from the user and then saved it to a static variable and then used this variable to pass the data to all the other views .
Thanks anyways