Develop Reference

Null Reference Exception when calling iText7 PdfAcroForm.GetAcroForm() in .Net Core 3.1 class library

I am working on converting an application to .Net Core 3.1, and in my class library I am generating a PDF form from an existing template, and filling that form with data. In ITextSharp, the predecessor to IText7, the PdfAcroForm static method ".GetAcroForm()" worked perfectly, but in the current version of iText7 (7.1.12) a Null Reference Exception is thrown. I have followed the documentation to the best of my ability, but I am unsure how to continue. Any suggestions would be appreciated.
NOTE: The template path exists, the new document shows that it has been filled properly, and it is impossible to "new" a PdfAcroForm, you are required to use the static .GetAcroForm() method.
A null check will not solve this issue, as the object should never be null. The documentation indicates that the .GetAcroForm() method will create a new form if the parameter "createNotExist" is set to true, which I have done here.
I have researched and have located an issue on the iText GitHub that indicates that this issue was "fixed" around a year ago: https://github.com/itext/itext7/pull/44#issue-351612749
The following is the method which prepares the forms:
public string DocumentGenerator(string templatePath, FormFieldSet[] formFieldSet, bool useSpecailOutputPath)
{
if(!File.Exists(templatePath))
{
throw new Exception("The template file provided does not exist: MC-071(iText)");
}
string newFile = useSpecailOutputPath ?
m_SpecialOutputPath :
Path.GetTempPath() + Guid.NewGuid().ToString() + ".pdf";
try
{
PdfDocument newDocument = new PdfDocument(new PdfReader(templatePath), new PdfWriter(newFile));
PdfAcroForm acroForm = PdfAcroForm.GetAcroForm(newDocument, true); // <=== Exception Thrown Here
foreach (FormFieldSet fs in formFieldSet)
{
acroForm.GetField(fs.FieldName).SetValue(fs.FillValue);
}
// Sets form flattening
acroForm.FlattenFields();
// Closes and writes the form
newDocument.Close();
return newFile;
}
catch { return string.Empty; };
}
Any suggestions would be greatly appreciated

I had the same problem, and after digging down all the way to iText7's internal objects and methods, I finally "solved" my problem.
Apparently iText has some internal errors/exceptions that they are just sort of "skipping" and "pushing past", because I realized by accident that I had "Enable Just My Code" in Visual Studios disabled, and so my system was trying to debug iText7's code as well as mine. The moment that I re-enabled it in my Visual Studio settings (Tools > Options > Debugging > General > Enable Just My Code checkbox), the problem magically went away.
So I spent four hours trying to troubleshoot a problem that was in THEIR code, but that they apparently found some way to work around and push through the method anyways even on a null reference failure.
My convert to PDF function is now working just fine.

Just an update to anyone looking for this issue. This is a known issue and is fixed in the current development branch. You are safe to bypass the exception in visual studio until it is corrected. This has no negative impact on the functionality and is the result of a misplaced return in the original iText7 source.

Identify Cause of Serialization Error Coming From Inside Library/NuGet Package

Sometimes when calling the Mastercard MATCH API via the NuGet package MasterCard-Match, I will get a JSON deserialization exception:
Unexpected character encountered while parsing value: <. Path '',
line 0, position 0.
The exception is from MasterCard.Core with an inner exception from Newtonsoft.Json, both have the same message.
It looks like I'm receiving HTML ('<' at line 0, position 0) and the library is trying to deserialize it as JSON. My guess is that the MasterCard API is sending back an HTML error page instead of a JSON error. But I can't step into the function call to "see" the response its getting before throwing the exception.
As per the documentation I create a request map with the provided data and call TerminationInquiryRequest.Create(map), this is the line the exception is thrown. This function call is a black box, I can't step into it, it just throws the exception.
try
{
RequestMap requestMap = CreateRequestMap();
// This line throws the exception
TerminationInquiryRequest apiResponse = TerminationInquiryRequest.Create(requestMap);
}
catch(Exception e)
{
// Exception handling
}
I've made over 11,000+ calls using this library and only 32 have had this error, but of course I get to hear about it every time it happens.
Is there any way to debug libraries that I'm not aware of, or a way to view the response that the library is getting from the API?
I already have some logic to wait and retry the call if it fails.

Stackoverflow exception in JSON.net

I am using MongoDB + C# + Knockout. Recently I have added new column "SubmitCount" of data type "int" in my existing database (MongoDB).
When I query mongodb using C#, it is giving me Stackoverflow exception with no stack trace. I figured out it is giving me exception at:
var query = Query.EQ("Shelf", "Create");
var result = CollectionName.FindAs<BsonDocument>(query);
//Throwing exception at below line
var trialList = (from clnTrial in result
select new { TrialID = clnTrial["TrialID"].ToString(), CreatedBy = clnTrial["CreatedBy"].ToString() }).Distinct().ToList();
It was working properly before adding new column.
I searched a lot but found nothing. Any help would be appreciated.
EDIT: I just rerun the code removing "ToList()" now it is not giving exception. :-/. But I need ToList().

This is bit weird. But After trying all possible solutions, I noticed that NewtonSoft.JSON dll I was using was not of latest version.
I updated DLL through Nuget and Bingo! it starts working again.
Some suggestion for updating NewtonSoft.JSON dll
First uninstall old one and then update to latest one.
If you get FileLoadException for referring two NewtonSoft.JSON dll of different version then try this solution FileLoadException was unhandled by user code

Getting MissingMethodException when using Manatee.trello to get list of users

I have the following code which is intended to fetch a list of all the user of an organisation.
public static IEnumerable<Member> ListTrelloUsers()
{
var serializer = new ManateeSerializer();
TrelloConfiguration.Serializer = serializer;
TrelloConfiguration.Deserializer = serializer;
TrelloConfiguration.JsonFactory = new ManateeFactory();
TrelloConfiguration.RestClientProvider = new RestSharpClientProvider();
TrelloAuthorization.Default.AppKey = ApplicationKey;
TrelloAuthorization.Default.UserToken = GrandToken;
var myOrganization = Member.Me.Organizations.FirstOrDefault().Id; //Exception thrown here.
var orgToAddTo = new Organization(myOrganization);
return orgToAddTo.Members.AsEnumerable();
}
But I'm getting a
System.MissingMethodException
thrown on
RestSharp.IRestRequest RestSharp.RestRequest.AddFile(System.String, Byte[], System.String)
So why is this exception thrown and what should the correctly working code look like?
Clarifications
I will also accept working C#/ASP.Net MVC code that isn't based on Manatee.Trello as an answer. (Including pure API-calls.)
I have tried using the Organisation ID directly as
var orgToAddTo = new Organization(OrganisationId);
but that just caused the same exception to be thrown later when I make a call to the method's returned object (e.g. using Count()).
UPDATE: I tried setting the build to Release instead of Debug and now the (same) exception is instead thrown at
TrelloConfiguration.RestClientProvider = new RestSharpClientProvider();

This is an issue with RestSharp that I reported quite some time ago, though they deny that it's a problem. If you're using .Net 4.5+, you can try the Manatee.Trello.WebApi package instead of Manatee.Trello.RestSharp.
TrelloConfiguration.RestProvider = new WebApiClientProvider();
Here's my Trello card for tracking the issue. This and this are the RestSharp issues I created.
I have been able to recreate this as well, but have received no help from them to resolve it.

Apperently, the class with missing method is located in an assembly, which differ from the one, which you used while compiling the project. Double check and make sure both at compiling and at execution you use the same assembly with the aforementioned class.
That is my best clue based on the info you've provided.
basically, check project references and make sure, you use correct ones for the class-holding assembly.

Unsupported Media Type error when using json-patch in Ramone

Update: I downloaded Ramone project, added it to my project and then ran the application again with debugger. The error is shown below:
public MediaTypeWriterRegistration GetWriter(Type t, MediaType mediaType)
{
...
CodecEntry entry = SelectWriters(t, mediaType).FirstOrDefault(); => this line throws error
...
}
Error occurs in CodecManager.cs. I am trying to figure out why it does not recognize json-patch media type. Could it be because writer is not being registered correctly? I am looking into it. If you figure out the problem, please let me know. Since you are the author of the library, it will be easier for you to figure out the issue. I will have to go through all the code files and methods to find the issue. Thanks!
I was excited to know that Ramone library supports json-patch operations but when I tried it, I got following error:
415- Unsupported Media Type
This is the same error that I get when I use RestSharp. I thought may be RestSharp does not support json-patch and errors out so I decided to try Ramone lib but I still get same error. Endpoint has no issues because when I try same command using Postman, it works but when I try it programmatically in C#, it throws unsupported media type error. Here is my code:
var authenticator = new TokenProvider("gfdsfdsfdsafdsafsadfsdrj5o97jgvegh", "sadfdsafdsafdsfgfdhgfhehrerhgJ");
JsonPatchDocument patch = new JsonPatchDocument<MetaData>();
patch.Add("/Resident2", "Boyle");
//patch.Replace("/Resident", "Boyle");
RSession = RamoneConfiguration.NewSession(new Uri("https://api.box.com"));
RSession.DefaultRequestMediaType = MediaType.ApplicationJson;
RSession.DefaultResponseMediaType = MediaType.ApplicationJson;
Ramone.Request ramonerequest = RSession.Bind("/2.0/files/323433290812/metadata");
ramonerequest.Header("Authorization", "Bearer " + authenticator.GetAccessToken(code).AccessToken);
//var ramoneresponse = ramonerequest.Patch(patch); //results in error: 405 - Method Not Allowed
var ramoneresponse = ramonerequest.Put(patch); //results in error: 415 - Unsupported Media Type
var responsebody = ramoneresponse.Body
Endpoint information is available here: http://developers.box.com/metadata-api
I used json-patch section in the following article as a reference:
http://elfisk.dk/Ramone/Documentation/Ramone.pdf
By the way I tried Patch() method (as shown in above ref. article) but that resulted in "Method not allowed" so I used Put() method which seems to work but then errors out because of json-patch operation.
Any help, guidance, tips in resolving this problem will be highly appreciated. Thanks much in advance.
-Sham

The Box documentation says you should use PUT (which is quite a bit funny). The server even tells you that it doesn't support the HTTP PATCH method (405 Method Not Allowed) - so PUT it must be.
Now, you tell Ramone to use JSON all the time (RSession.DefaultRequestMediaType = MediaType.ApplicationJson), so you end up PUT'ing a JSON document to Box - where you should be PUT'ing a JSON-Patch document.
Drop the "RSession.DefaultRequestMediaType = MediaType.ApplicationJson" statement and send the patch document as JSON-Patch with the use of: ramonerequest.ContentType("application/json-patch+json").Put(...).