System.NullReferenceException: 'Object reference not set to an instance of an object.' #2301

Rrader30 created 3 years ago

ABP Framework version: v4.3
UI type: Angular
DB provider: EF Core
Tiered (MVC) or Identity Server Separated (Angular): Seperated
Exception message and stack trace:
Steps to reproduce the issue:"

I have a background job where I am attempting to select records from a trap table. When the code gets to _list = query.ToList() I get the error System.NullReferenceException: 'Object reference not set to an instance of an object.' in List.cs. What am I doing wrong? Any ideas of why this error is occuring?

foreach (var row in values)
                {
                    IQueryable<Trap> queryable = await _trapsSheet.GetQueryableAsync();
                    var query = queryable.Where(x => x.Asset.Equals(ConvertInt64(row[0].ToString())));
                   
                    if(query.Any())
                    {
                        try
                        {
                            var _c1 = MapValues(row);

                            List<Trap> _list = new List<Trap>();
                            _list = query.ToList();
                            Trap _result = ObjectMapper(_c1, _list[0]);
                            mTrapExist.Add(_result);
                        }catch(Exception ex)
                        {
                            System.Diagnostics.Debug.WriteLine(ex.Message);
                        }
                       
                    }
                    else
                    {
                        try
                        {
                            Trap _result = MapValues(row);
                            System.Diagnostics.Debug.WriteLine(_result.Asset.ToString());
                            mTrap.Add(_result);
                        
                        }catch(Exception ex)
                        {
                            System.Diagnostics.Debug.WriteLine(ex.ToString());
                        }
                        
                    }
                }

maliming created 3 years ago

Support Team Fullstack Developer

Can you share the full error stack?

Rrader30 created 3 years ago

This is all I get

System.NullReferenceException
HResult=0x80004003
Message=Object reference not set to an instance of an object.
Source=Microsoft.EntityFrameworkCore.Relational
StackTrace:
at Microsoft.EntityFrameworkCore.Query.Internal.SplitQueryingEnumerable`1.Enumerator.Dispose()

Rrader30 created 3 years ago

Maliming. I did. That is all it is giving me.

maliming created 3 years ago

Support Team Fullstack Developer

Can you check this (x => x.Asset.Equals(ConvertInt64(row[0].ToString())))

Try to use constant expressions.

Rrader30 created 3 years ago

I did and I am still getting the error.

maliming created 3 years ago

Support Team Fullstack Developer

Maybe the x.Asset is null. Can you try to include it? or ignore it?

Rrader30 created 3 years ago

So I check the database and the records exist. Here is a snippet of the table.

Rrader30 created 3 years ago

The funny part is, I can insert records just fine with this code. This is within the same class for the background job.

try
{
Trap _result = MapValues(row);
System.Diagnostics.Debug.WriteLine(_result.Asset.ToString());
mTrap.Add(_result);

}catch(Exception ex)
{
System.Diagnostics.Debug.WriteLine(ex.ToString());
}

if(mTrap.Count > 0)
{
await _trapsSheet.InsertManyAsync(mTrap, true);
await uow.SaveChangesAsync();
}

Rrader30 created 3 years ago

Not sure I am understanding. Here is what I have

private readonly IUnitOfWorkManager _unitOfWorkManager;
private readonly IRepository<Trap, Guid> _trapsSheet;
private readonly IObjectMapper _objectMapper;
private readonly IEmailSender _emailSender;
private readonly ITemplateRenderer _templateRenderer;
private static readonly string[] Scopes = { SheetsService.Scope.Spreadsheets };

public TrapLoader(IUnitOfWorkManager unitOfWorkManager, IRepository<Trap, Guid> traps, IObjectMapper objectMapper, IEmailSender emailSender, ITemplateRenderer templateRenderer)
{
_unitOfWorkManager = unitOfWorkManager;
** _trapsSheet = traps**;
_objectMapper = objectMapper;
_emailSender = emailSender;
_templateRenderer = templateRenderer;
}

maliming created 3 years ago

Support Team Fullstack Developer

You need to include your navigation entity.

https://support.abp.io/QA/Questions/2301#answer-c47f204b-9a58-626b-5c6a-3a00e7a19105

Rrader30 created 3 years ago

I'll give that a try in the AM. I'll tell you know what happens.

maliming created 3 years ago

Support Team Fullstack Developer

👍

Rrader30 created 3 years ago

I went in and attempted to use .Include, but it appears .Include is not part of the IQueryable. A little background. I am using the IQueryable because when I inject the service and attempt to use the service directly in a background job I get Access denied because the user isnt authenticated, so instead I am accessing the data using the IRepository<Trap, Guid>. I have done this in other background jobs without any issues, but this one is throwing an exception and not sure why.

Rrader30 created 3 years ago

So I regenerated the table with a different name with ABP SUITE and now things seem to be working. What I would like to understand is why did the original not work properly as it was generated with ABP Suite?