I have the following code (in MVC3):
public JsonResult GetTown(string term)
{
db = new SHAMUTEntities1();
var data = db.towns.Where(t => t.name.Contains(term))
.Take(10)
.Select(t => new {label=t.name }).ToArray();
return Json(data, JsonRequestBehavior.AllowGet);
}
}
I get the following error:
System.Web.Helper.Json is a type but is used like a variable
Can anybody help with this.
thanks
Json is a method of the System.Web.Mvc.Controller class of ASP.NET MVC 3. Since it's not compiling, you are probably using it in a class that does not derived from Controller.
To fix it, just return the data instance from your method and convert it to JSON in a controller metod.
Related
I'm trying to use Firebase and its callable Cloud Functions for my Unity project.
With the docs and different posts I found on the web I struggle to understand how returning data works. (I come from Azure Functions in C#)
I use TypeScript, and try to return a custom object CharactersResponse:
export class CharactersResponse //extends CustomResponse
{
Code!: CharactersCode;
CharacterID?: string;
}
export enum CharactersCode
{
Success = 0,
InvalidName = 2000,
CharacterNameAlreadyExists = 2009,
NoCharacterSlotAvailable = 3000,
InvalidCharacterClass = 4000,
EmptyResponse = 9000,
UnknownError = 9999,
}
(Custom Response is a parent class with only an UnknownErrorMessage string property, that I use for adding extra message when needed, but only in Unity. I don't need it in my functions.)
I have the same in my C# Unity Project:
public class CharactersResponse : CustomResponse
{
public CharactersCode Code;
public string CharacterID;
}
public enum CharactersCode
{
Success = 0,
InvalidName = 2000,
CharacterNameAlreadyExists = 2009,
NoCharacterSlotAvailable = 3000,
InvalidCharacterClass = 4000,
EmptyResponse = 9000,
UnknownError = 9999,
}
I'm still learning but I found it useful to do this way for displaying correct messages in Unity (and also regarding localization).
When the Code is 0 (Success), I will usually need to get some data at the same time like in this example CharacterID, or CharacterLevel, CharacterName etc.. CharacterResponse will be used for all functions regarding Characters like "GetAllCharacters", "CreateNewCharacter" etc..
My Function (CreateNewCharacter) looks like this:
import * as functions from "firebase-functions";
import { initializeApp } from "firebase-admin/app";
import { getFirestore } from "firebase-admin/firestore";
import { CharactersResponse } from "./CharactersResponse";
import { CharactersCode } from "./CharactersResponse";
import { StringUtils } from "../Utils/StringUtils";
// DATABASE INITIALIZATION
initializeApp();
const db = getFirestore();
// CREATE NEW CHARACTER
export const CreateNewCharacter =
functions.https.onCall((data, context) =>
{
// Checking that the user is authenticated.
if (!context.auth)
{
// Throwing an HttpsError so that the client gets the error details.
throw new functions.https.HttpsError('failed-precondition', 'The function must be called ' +
'while authenticated.');
}
// TEST
data.text = '';
// Authentication / user information is automatically added to the request.
const uid: string = context?.auth?.uid;
const characterName: string = data.text;
// Check if UserID is present
if (StringUtils.isNullOrEmpty(uid))
{
// Throwing an HttpsError so that the client gets the error details.
throw new functions.https.HttpsError('failed-precondition', 'Missing UserID in Auth Context.');
}
const response = new CharactersResponse();
if (StringUtils.isNullOrEmpty(characterName))
{
response.Code = CharactersCode.InvalidName;
console.log("character name null or empty return");
return response; // PROBLEM IS HERE *****************
}
console.log("end return");
return "Character created is named : " + characterName + ". UID = " + uid;
});
In Unity, the function call looks like this:
private static FirebaseFunctions functions = FirebaseManager.Instance.Func;
public static void CreateNewCharacter(string text, Action<CharactersResponse> successCallback, Action<CharactersResponse> failureCallback)
{
Debug.Log("Preparing Function");
// Create the arguments to the callable function.
var data = new Dictionary<string, object>();
data["text"] = text;
// Call the function and extract the operation from the result.
HttpsCallableReference function = functions.GetHttpsCallable("CreateNewCharacter");
function.CallAsync(data).ContinueWithOnMainThread((task) =>
{
if (task.IsFaulted)
{
foreach(var inner in task.Exception.InnerExceptions)
{
if (inner is FunctionsException)
{
var e = (FunctionsException)inner;
// Function error code, will be INTERNAL if the failure
// was not handled properly in the function call.
var code = e.ErrorCode;
var message = e.Message;
Debug.LogError($"Code: {code} // Message: {message}");
if (failureCallback != null)
{
failureCallback.Invoke(new CharactersResponse()
{
Code = CharacterCode.UnknownError,
UnknownErrorMessage = $"ERROR: {code} : {message?.ToString()}"
});
}
}
}
}
else
{
Debug.Log("About to Deserialize response");
// PROBLEM IS HERE *********************
CharactersResponse response = JsonConvert.DeserializeObject<CharactersResponse>(task.Result.Data.ToString());
Debug.Log("Deserialized response");
if (response == null)
{
Debug.LogError("Response is NULL");
}
else
{
Debug.Log("ELSE");
Debug.Log($"Response: {response}");
Debug.Log(response.Code.ToString());
}
}
});
}
The problem :
In my Unity C# code, task.Result.Data contains the CharactersCode I've set in my function, but I can't find a way to convert it to CharactersResponse. (It worked in Azure Functions). Moreover, the line just after Deserialization Debug.Log("Deserialized response"); is not executed. The code seems stuck in the deserialization process.
I tried with and without extending my TypeScript class with CustomResponse(because I don't need it in my Function so I didn't extended it at first).
I also tried setting a CharacterID because I thought maybe it didn't like the fact that this property was missing but the result is the same.
I don't understand what is the problem here? If any of you can help.
Thanks.
HttpsCallableResult.Data is of type object!
=> Your ToString will simply return the type name something like
System.Object
or in your case the result is a dictionary so it prints out that type.
=> This is of course no valid JSON content and not what you expected.
Simply construct the result yourself from the data:
var result = (Dictionary<string, object>)task.Result.Data;
CharactersResponse response = new CharactersResponse
{
Code = (CharactersCode)(int)result["Code"],
CharacterID = (string)result["CharacterID"];
};
I wanted to implement derHugo's solution but couldn't find a way to convert task.Result.Data to Dictionary<string, object>.
The code was stuck at var result = (Dictionary<string, object>)task.Result.Data; even in step by step debugging and no error popped up.
OLD SOLUTION:
So I did a little research and stumbled upon this post and ended up using this instead :
var json = JsonConvert.SerializeObject(task.Result.Data);
CharactersResponse response = JsonConvert.DeserializeObject<CharactersResponse>(json);
I basically convert the task.Result.Data to JSON and convert it back to CharactersResponse and it works. I have what I wanted.
However, I seem to understand that it is not the best solution performance-wise, but for now it is okay and I can now move forward in the project, I'll try to find a better solution later.
NEW SOLUTION:
I wanted to try one last thing, out of curiosity. I wondered what if I convert to JSON at the beginning (in my function) instead of at the end (in my Unity app). So I did this in my function's TypeScript code:
response.Code = CharactersCode.InvalidName;
var r = JSON.stringify(response); // Added this line
return r; // return 'r' instead of 'response'
In my C# code, I retried this line of code:
CharactersResponse response = JsonConvert.DeserializeObject<CharactersResponse>(task.Result.Data.ToString());
And it works ! I just needed to convert my object to JSON in my function before returning it. It allows me to "save" one line of code to process on the client side compared to the old solution.
Thanks derHugo for your answer as it helped me finding what I want.
I'm learning how to use json, not used to Dart null safety & I don't like it so far. But I will have no choice but to adapt to it. I'm trying to parse my json object list into a list of objects. I was able to work out the basics in my main, but when I attempt to create an actual method in a class using the same structure I'm getting a null error. As far as I can tell I'm doing the exact same thing in both with addition of the loop for iterating the entire json list.
Note: I of course did try inserting the optional ? where it asks but the IDE will not allow this.
Can someone help with explaining what I'm doing wrong here?
Error for class method jsonToDatabaseSyncItem()
lib/services/remote_database_services.dart:52:43: Error: Property 'length' cannot be accessed on 'List<dynamic>?' because it is potentially null.
- 'List' is from 'dart:core'.
Try accessing using ?. instead.
final jsonListLength = jsonObjectList.length;
^^^^^^
lib/services/remote_database_services.dart:55:38: Error: Operator '[]' cannot be called on 'List<dynamic>?' because it is potentially null.
- 'List' is from 'dart:core'.
var jsonObject = jsonObjectList[index]['DatabaseSyncItem'];
Class method (class- RemoteDatabaseService)
// This method will get server database
Future<List<dynamic>?> getRemoteDatabase() async {
final events = QueryBuilder<ParseObject>(ParseObject('Event'));
final apiResponse = await events.query();
if (apiResponse.success && apiResponse.result != null) {
return apiResponse.results;
} else {
return [];
}
}
// Method to parse json result list back to objects
Future<List<dynamic>?> jsonToDatabaseSyncItem() async {
final remoteDatabaseList = await getRemoteDatabase();
final jsonObjectList = await Future.value(remoteDatabaseList); /// This method throws the above
final jsonListLength = jsonObjectList.length; /// error when run in main
for (var index = 0; index == jsonListLength; index++) {
var jsonObject = jsonObjectList[index]['DatabaseSyncItem'];
print(jsonObject);
}
}
Main file working code
Future<void> main(List<String> arguments) async {
final test = remoteDatabaseServices.getRemoteDatabase();
Future<List<dynamic>?> getList() {
return Future.value(test);
}
var list = await getList();
print(list?.length);
var jsonObject = list![0]['DatabaseSyncItem'];
print(jsonObject);
var toObject = DatabaseSyncItem.fromJson(jsonObject);
print(toObject);
}
Your problem with null-safety seems to be a missing understanding about the feature. I will recommend you to read through the documentation here and read all the chapters: https://dart.dev/null-safety
About your code, you should consider when something can be null and when you can check the null and handle that case. In your example, it seems like getRemoteDatabase() should just return an empty List if an error happens or no result is returned. So we don't need to have the return type of this method as Future<List<dynamic>?> if we rewrite the method a bit:
Future<List<dynamic>> getRemoteDatabase() async {
final events = QueryBuilder<ParseObject>(ParseObject('Event'));
final apiResponse = await events.query();
if (apiResponse.success) {
return apiResponse.results ?? <dynamic>[];
} else {
return <dynamic>[];
}
}
(the ?? operator will here test if apiResponse.results is null, if that is the case, we return <dynamic>[]. If not, we use the value of apiResponse.results).
Since this method is now guarantee to never return null, we can use that to simplify the next method. I have also rewritten it to use a for-each loop since we don't really need the index of each element.
Future<void> jsonToDatabaseSyncItem() async {
final jsonObjectList = await getRemoteDatabase();
for (final jsonObject in jsonObjectList) {
print(jsonObject['DatabaseSyncItem']);
}
}
I have also removed this line since it does nothing at all. If remoteDatabaseList is a Future you should just await on that instead of creating a new Future.
final jsonObjectList = await Future.value(remoteDatabaseList);
Also, the return type of jsonToDatabaseSyncItem() have been changed to Future<void> since we are never returning any value.
I am a little confused about your main but I think this is where it is most clear that you got a confused about Future and null-safety. I have tried to rewrite it so it is much cleaner but should still do the same:
Future<void> main(List<String> arguments) async {
final list = await getRemoteDatabase();
print(list.length);
final dynamic jsonObject = list[0]['DatabaseSyncItem'];
print(jsonObject);
final toObject = DatabaseSyncItem.fromJson(jsonObject);
print(toObject);
}
I've been in the process of migrating a code base from Angular 4.x to 5.x, and I'm running into a strange issue. I have a service function, that is intended to return a list of objects to the front end, which I then massage into a specific data format. I know I'll need to keep the mapping, but I'm a little miffed that it's returning just plain string data.
The original function is this: (using Http from #angular/http just renamed to HttpClient)
public GetVendors(showAll = true, screenArea: number = 0): Observable<Array<SelectModel>> {
let link = AppSettings.API_COMMON_VENDORS;
let params: URLSearchParams = new URLSearchParams();
params.set('showAll', showAll.toString());
params.set('screenArea', screenArea.toString());
let requestOptions = new RequestOptions();
requestOptions.search = params;
return this.httpClient.get(link, requestOptions).map(response => {
let result = JSON.parse(response.json());
let list = new Array<SelectModel>();
let vendors: Array<any> = result;
vendors.forEach(vendor => {
list.push(this.CreateSelectModel(vendor));
});
return list;
});
}
and after ripping out ALL of the Http code, here's the function again using HttpClient from #angular/common/http
public GetVendors(showAll = true, screenArea: number = 0): Observable<Array<SelectModel>> {
let link = AppSettings.API_COMMON_VENDORS;
let params: HttpParams = new HttpParams()
.set('showAll', showAll.toString())
.set('screenArea', screenArea.toString());
return this.httpClient.get<Array<any>>(link, {params}).map(response => {
let list = new Array<SelectModel>();
response.forEach(vendor => {
list.push(this.CreateSelectModel(vendor));
});
return list;
});
}
The issue with this is it kind of defeats the purpose of the new client parsing json for me. The response object is a string representing the JSON of the data I requested, but it's still in a string form, and not the type defined in the get<>() call.
What am I doing wrong here? shouldn't it be parsed already?
Sample Response Data A'la Network Tools in Chrome Dev Tools:
Sample Response Body:
Dev Tools Screenshot with Value of response
The backend (C#) responds with this:
[HttpGet]
public JsonResult Vendors(bool showAll = false, int screenArea = 0)
{
var vendors = _commonBL.GetVendorsSlimForUser(UserModel, UserModel.CustomerId, showAll, screenArea);
return GetJson(vendors);
}
this is how it worked before the Http => HttpClient migration, and it worked with ONE JSON.parse() The data in the return line is simply a standard List<T>
This is what the raw response for your data should look like:
[{"Id":1234,"Name":"Chris Rutherford"}]
But this is what it actually looks like:
"[{\"Id\":1234,\"Name\":\"Chris Rutherford\"}]"
So somewhere in your server code, you have applied JSON encoding twice. Once you correct that, HttpClient will do the right thing.
I'd quote an answer from this thread. Hope it will shed some light on how things work, read it thoroughly it enlightened me tough its not easy to find.
TypeScript only verifies the object interface at compile time. Any object that the code fetches at runtime cannot be verified by
TypeScript.
If this is the case, then things like HttpClient.Get should not
return Observable of type T. It should return Observable of type Object because
that's what is actually returned. Trying to state that it returns T
when it returns Object is misleading.
In the documentation the client's return section says this:
#return an Observable of the body as
type T.
In reality, the documentation should say:
#return an Observable of the body which
might be T. You do not get T back. If you got T back, it would
actually be T, but it's not.
I have an Action method that returns JSON, for brevity, I excluded code. :
public ActionResult SetMasterLocation(string masterValue)
{
json = new JavaScriptSerializer().Serialize(masterLocation);
return Json(json, JsonRequestBehavior.AllowGet);
}
I need to call this method and access the JSON string that gets returned:
var jVendors = SetMasterLocation(masterValue);
When I run it and inspect the output, I see the JSON string in a dynamic property called Data:
But if I try to access data like this, the app will not compile because the compiler says Cannot resolve symbol 'Data':
var jVendors = SetMasterLocation(masterValue);
var data = jVendors.Data;
How do I access the Data property at runtime?
Return JsonResult
return new JsonResult()
{
Data = someData,
JsonRequestBehavior = JsonRequestBehavior.AllowGet
};
Then, you can access Data property of the result
I have been trying to get an Entity Framework model to convert to JSON to display in a web page. The Entity object is created fine but something fails when it is returned. Below is the code from my ASP.NET Web API project. By setting a breakpoint I can see the object collection is created just fine.
public class ClientsController : ApiController
{
public IEnumerable<Client> GetAllClients()
{
using (var context = new MyClientModel.MyEntities())
{
var query = context.Clients.Where(c => c.State == "CA");
var customers = query.ToList();
return customers;
}
}
}
Here is the HTML/Javascript code I use to call the ASP.NET Web API
<script>
var uri = 'api/clients';
$(document).ready(function () {
// Send an AJAX request
$.getJSON(uri)
.done(function (data) {
// On success, 'data' contains a list of products.
alert('Made it!'); // ** Never reaches here **
$.each(data, function (key, item) {
// Add a list item for the product.
$('<li>', { text: item }).appendTo($('#clients'));
});
});
});
</script>
I use Fiddler to view the response and it returns a .NET error that says ...
The 'ObjectContent' type failed to serialize the response body for content type 'application/json; charset=utf-8'."
and the inner exception message is ...
Error getting value from 'Patients' on 'System.Data.Entity.DynamicProxies.Client
Patients is a related entity in my model but I am confused why it would be an issue as I am only returning Client objects.
I found a solution that works, though I admit I am not sure exactly how it works. I added the line context.Configuration.ProxyCreationEnabled = false; to my method that returns the object collection and all my objects were returned. I got the code from the following SO Question - WebApi with EF Code First generates error when having parent child relation.
public class ClientsController : ApiController
{
public IEnumerable<Client> GetAllClients()
{
using (var context = new MyClientModel.MyEntities())
{
context.Configuration.ProxyCreationEnabled = false; // ** New code here **
var query = context.Clients.Where(c => c.State == "CA");
var customers = query.ToList();
return customers;
}
}
}