I have a Blazor Webassembly project with a controller method as follows:
[HttpGet]
public async Task<List<string>> GetStatesForProfile()
{
IConfigurationSection statesSection = configuration.GetSection("SiteSettings:States");
var sections = statesSection.GetChildren();
var states = statesSection.GetChildren().Select(s => s.Key).ToList<string>();
return states;
}
The razor page calls this method:
private async Task<bool> GetStatesModel()
{
try
{
States = await http.GetJsonAsync<List<string>>("api/account/getstatesforprofile");
...
}
catch (Exception ex)
{
Console.WriteLine($"Exception: {ex.Message}, Inner: {ex.InnerException.Message}");
}
I get this Exception:
Exception: '<' is an invalid start of a value.
I read these values from appsettings.json file, And there is no '<' in values.
{
"SiteSettings": {
"States": {
"New York": ["NYC"],
"California": ["Los Angeles", "San Francisco"]
}
}
Also I put a breakpoint in the controller method and it doesn't hit.
What is this error? Is it from parsing json? and how to resolve this?
I had a very similar problem.
In the end it turned out that my browser had cached the HTML error page (I guess I had some problems with the code when I first tried it). And no matter how I tried fixing the code I still only got the error from cache. Clearing my cache also cleared the problem.
It happens when you're trying to access an API that doesn't exist. You have to check your API project connectionstring under AppSettings and make sure it's correct and running. If it's a Blazor project, you can set it as your default project, execute and see if you get a json response.
Most probably the response you are receiving is html instead of actual JSON format for the endpoint you are requesting. Please check that.
An as HTML usually starts with <html> tag, the JSON validator fails on the very first character.
You should also clear any cache, that might be interfering with the returned data. (this has helped people resolve this same issue)
I know this is an old question, but it's one of the top results when Googling the error.
I've just spent more time than I care to admit to tracking down this error. I had a straightforward Blazor hosted app, basically unchanged from the template. It worked just fine when run locally, but when published to my web host API calls failed. I finally figured out that the problem was that I was running the publish from the Client project. When I changed to the Server project it worked properly.
Hopefully my long frustration and slight stupidity will save someone else making a similar mistake.
Seems like your api is not not accessible and its returning error HTML page by default.
You can try below solution:-
I think you are using httpclient to get data to blazor application.
If you have separate projects in solution for blazor and web api,
currently your startup application may set to run blazor project only.
Change startup projects to multiple (blazor and web api app) and give httpClient url in startup of blazor application, as webApi application url, that may solve your issue.
This error indicates a mismatch of the project targeting framework version and installed runtime on the machine. So make sure that the target framework for your project matches an installed runtime - this could be verified by multiple means; one of them is to check out the Individual Components tab of the Visual Studio Installer and lookup the target version.
E.g., there is the TargetFramework attribute in the proj file:
<PropertyGroup>
<TargetFramework>net5.0</TargetFramework>
</PropertyGroup>
Then launch the Visual Studio Installer, click Modify, and visit the Individual Components tab:
Install the missing runtime (.NET 5 Runtime in this case) and you're good to go.
I got the same error. Red herring. use your browser or postman to check your api endpoint is returning the json data and not some HTML. In my case my "api/companytypes" had a typo.
private CompanyType[] companytypesarray;
private List<CompanyType> CompanyTypeList;
private List<CompanyType> CompanyTypeList2;
public async Task<bool> LoadCompanyTypes()
{
//this works
CompanyTypeList = await Http.GetFromJsonAsync<List<CompanyType>>("api/companytype");
//this also works reading the json into an array first
companytypesarray = await Http.GetFromJsonAsync<CompanyType[]>("api/companytype");
CompanyTypeList2 = companytypesarray.ToList();
return true;
}
I know this is an old question, but I had the same problem. It took some searching, but I realized that the return data was in XML instead of JSON.
I'm assuming your "http" variable is of type HttpClient, so here's what I found worked for me.
By setting the "Accept" header to allow only JSON, you avoid a miscommunication between your app and the remote server.
http.DefaultRequestHeaders.Add("Accept", "application/json");
States = await http.GetJsonAsync<List<string>>("api/account/getstatesforprofile");
I had the same issue when passing in an empty string to a controller method. Creating a second controller method that doesn't accept any input variables, and just passing an empty string to the first method helped to fix my problem.
[HttpGet]
[ActionName("GetStuff")]
public async Task<IEnumerable<MyModel>> GetStuff()
{
return await GetStuff("");
}
[HttpGet("{search}")]
[ActionName("GetStuff")]
public async Task<IEnumerable<MyModel>> GetStuff(string search)
{
...
}
Versions of package
Try to update your packages to old or new version. In my case, system.net.http.json is updated from 6.0 to 5.0
Likely you are using an Asp.NetCore hosted WASM application. By default the client's App.razor has something similar to:
<CascadingAuthenticationState>
<Router AppAssembly="#typeof(Program).Assembly">
<Found Context="routeData">
<AuthorizeRouteView DefaultLayout="#typeof(MainLayout)"
RouteData="#routeData">
<NotAuthorized>
<RedirectToLogin />
</NotAuthorized>
<Authorizing>
<Loading Caption="Authorizing..."></Loading>
</Authorizing>
</AuthorizeRouteView>
</Found>
<NotFound>
<LayoutView Layout="#typeof(MainLayout)">
<p>Sorry, there's nothing at this address.</p>
</LayoutView>
</NotFound>
</Router>
</CascadingAuthenticationState>
Herein lies the problem. Since the Client and Server share the same base address, when the application cannot find "api/account/getstatesforprofile" it gives you the client's "Sorry, there's nothing at the address" page. Which is of course HTML.
I have not found the solution to this issue, but I am working on it and will reply once I find an issue.
I was having the same problem,
"JsonReaderException: '<' is an invalid start of a value."
In my case the url for the REST service was wrong.
I was using the URL from the client project. Then I looked at the Swagger screen,
https://localhost:44322/swagger/index.html
and noticed the right URL should start with "44322"...
Corrected, worked.
In my case, I had a comma (,) written mistakenly at the beginning of the appsettings.json file ...
Just check your file and verify
///////
my error details
//////
System.FormatException HResult=0x80131537 Message=Could not parse the JSON file.
Source=Microsoft.Extensions.Configuration.Json StackTrace: at line 16 This exception was originally thrown at this call stack: [External Code] Inner Exception 1: JsonReaderException: ',' is an invalid start of a value. LineNumber: 0 | BytePositionInLine: 0.
////
For me, most of the time it is the #lauri-peltonen answer above. However, now and again, depending on who wrote the controller I have found that this will work in Swagger but not when you call it via the client (at least in this Blazor project we are on.)
[HttpGet]
[Route("prog-map-formulations")]
public async Task<List<GetProgramMapFormulationsResult>> GetProgramMapFormulations(int formulationId)
{
...
}
It sends the request as:
api/formulation-performance-program-map/analytical-assoc-values?formulationId=1
And I get results in Swagger but failes with the '<' OP error.
When I change ONLY the route to:
[HttpGet]
[Route("prog-map-formulations/{formulationId:int}")]
public async Task<List<GetProgramMapFormulationsResult>> GetProgramMapFormulations(int formulationId)
{
...
}
It sends the request as:
api/formulation-performance-program-map/analytical-assoc-values/1
And this works in both Swagger as well as from the Client side in Blazor.
Of course, once updated, I did have to clear the cache!
If you delete "obj" folder in your directory then clean the solution and rebbuild it the exception will be resolved
In all these, there is two things that was my issue and realized, first off was that Route[("api/controller")] instead of Route[("api/[controller]")], that is missing square brackets. In the second exercise I was doing, with the first experience in mind, was from the name of the database. The database had a dot in the name (Stock.Inventory). When I change the database name to StockInventory it worked. The second one I am not so sure but it worked for me.
I want my data access layer to handle exceptions thrown by DocumentDB API provided via Microsoft.Azure.Documents.Client.DocumentClient class. For example, the optimistic concurrency check implemented using AccessCondition class, but others as well.
By looking at the exception thrown, the best way to recognize different DocumentClient-specific exceptions seems to be something like this:
try { ... }
catch (DocumentClientException exception)
when (exception.Error.Code == "Some magic here")
{
//let the user know how to recover from this..
}
I don't like such magic strings as they are not verifiable compile-time. It may contract a typo, or it may change on random moment with DocumentDB client/server changes, etc. Also, it is not clear which such magic codes I could/should be handling since I don't see the Microsoft.Azure.DocumentDB .net API containing any ErrorCodes enum or constants, nor find any list in documentation.
Where can I find a list of possible Error.Code values DocumentClient API can throw?
To make it even more confusing, the XmlDoc for DocumentClient.CreateDocumentAsync method suggest working instead on http status codes.
UPDATE: This question is not about Http status codes but DocumentClientException.Error.Code field as I assume the latter is more precise.
Where can I find a list of possible error codes values DocumentClient API can throw?
It's hard to find the completely list of error code that DocumentClinet API throw. The exception is depend on what your request.
For example, the optimistic concurrency check
Azure Cosmos DB uses ETags for handling optimistic concurrency.
When we retrieve a document from Azure Cosmos DB, it always contains an ETag property as apart of our document.
When we then want to send our request to replace a document, we can specify an AccessCondition with the ETag we received when we fetched out our document.
If the ETag we send is not current, the server will return a 412 Precondition Failed status code. In our .NET SDK, this is wrapped up in a DocumentClientException.
Here is an example that show the possible problems when the concurrency occurred.
By decompile the version 1.22.0 client, the code is set as a HttpStatusCode enum. I think all the possible values can be found here https://msdn.microsoft.com/en-us/library/system.net.httpstatuscode(v=vs.110).aspx then.
However, what really contains richer information for debug is the Error.Message. Might need to decompile the whole library to figure out, or wait for Microsoft to release the source codes, which is unlikely to happen since the latest update in github was 2 or 3 years ago.
public Error Error
{
get
{
if (this.error == null)
{
this.error = new Error()
{
Code = this.StatusCode.ToString(),
Message = this.Message
};
}
return this.error;
}
}
There is a list of the HTTP Status Codes for Azure Cosmos DB
I use the following code in my catch blocks
catch (DocumentClientException e)
{
var resp = new HttpResponseMessage
{
StatusCode = (HttpStatusCode) e.StatusCode,
Content = new StringContent(e.Message)
};
return resp;
}
Letting the user know how to handle the exception should be done on the client application.
When creating a normal CloseableHttpClient I can disable compression (and redirections) by doing
httpclient = HttpClients.custom()
.disableRedirectHandling()
.disableContentCompression()
.build();
This way I receive gzip data unaltered.
Now I'm trying the same with CloseableHttpAsyncClient, but the relevant methods are missing from HttpAsyncClients.custom():
asyncHttpClient = HttpAsyncClients.custom()
.disableContentCompression() // COMPILE ERROR
.build();
I'm just at the start of evaluating the feasability or rewriting my code to the async API so I might be missing something. How is the async client going to handle compressed content? Can its behavior be customized?
HttpAsyncClient 4.x currently does not support automatic content decompression.
Anytime that I use serializeJSON in cf9 the JSON it returns is prepended with '//'. This is pretty frustrating because even coldfusion will throw an error trying to decode that as json. For example:
var a = { stuff = 'some content' };
a = serializejSON( a ); // the content of a is now: //{"STUFF":"some content"}
b = deserializeJSON( a );
The above code will throw an error saying something like 'unable to parse character at position 1: /'. In order to make this work I have to do a string replace and swap out '' for the '//'.
I can't seem to find any information on this issue. Is this some sort of feature that I don't understand and is working as intended? Am I missing some sort of setting that fixes this?
You can disable this in the ColdFusion administrator. Go to Server Settings > Settings and uncheck Prefix serialized JSON with
There are, however, security implications if you turn this off. This helps protect your JSON data from cross-site scripting attacks and is explained more in depth in this StackOverflow answer
Quick update: A guy previously submitted a bug ticket to Adobe to disable the secure JSON prefix of the SerializeJSON function in the form of an attribute..
Ticket [Fixed]
Since then Adobe obliged and added the attribute useSecureJSONPrefix onto the SerializeJSON funtion.
Documentation
That way you can keep the secure setting in ColdFusion Administrator and simply disabled it where you don't need it.
I am facing some issues around SSL (HTTPS calls) in an Adobe Air application. There is a bug on Adobe's list and its the exact same issue that I've bumped into:- https://forums.adobe.com/thread/1116924
The recommended solution (unless Adobe fixes this - they haven't done so in over 2 years) is to use as3crypto's SSL.
Can anyone here help me with the same? Right now, my HTTPService, which uses the default built in Adobe's SSL capabilities, looks like:-
var params:Object = getPOSTParameters();
var _httpservice:HttpService = new HTTPService();
_httpservice.url = "https://myserver_url";
_httpservice.resultFormat = "text";
_httpservice.contentType="application/x-www-form-urlencoded";
_httpservice.method = "POST";
_httpservice.concurrency = "multiple";
_httpservice.requestTimeout=600000;
_httpservice.showBusyCursor = false;
_httpservice.addEventListener(IOErrorEvent.IO_ERROR, httpIOError);
_httpservice.addEventListener(HTTPStatusEvent.HTTP_RESPONSE_STATUS, httpResponseStatus);
var responder:Responder = new Responder(onResult, onError);
var token:AsyncToken = _httpservice.send(params);
token.addResponder(responder);
How should I go about implementing the same with as3crypto? Any example/ code pointers will be really helpful
There is no 100% working solution, at least I don't know it. When I needed https in Adobe Flash I used as3httpclient library where AS3Crypto used for implementig TLSSocket. It's much easier than write you own. But beware it's buggy and it isn't works in some cases.
EDIT:
There is documentation available here for me it was enough, there is no difference between http and https request (except URL).