NullReferenceException when inserting with Dapper

Question

When I run the following code I get a NullReferenceException saying that an object reference not set to an instance of the object. I've successfully inserted with dapper using less complex objects but the same format, so am not sure what I'm doing wrong.

public void Foo(IEnumerable<FogbugzCase> cases) 
{
    // using a singleton for the SqlConnection
    using (SqlConnection conn = CreateConnection())
    {
        foreach (FogbugzCase fogbugzCase in cases)
        {
            conn.Execute("INSERT INTO fogbugz.Cases(CaseId, Title, ProjectId, CategoryId, Root, MilestoneId, Priority, Status, EstimatedHours, ElapsedHours, AssignedTo, ResolvedBy, IsResolved, IsOpen, Opened, Resolved, Uri, ResolveUri, OutlineUri, SpecUri, ParentId, Backlog) VALUES(@BugId, @Title, @ProjectId, @CategoryId, @RootId, @MilestoneId, @Priority, @StatusId, @EstimatedHours, @ElapsedHours, @PersonAssignedToId, @PersonResolvedById, @IsResolved, @IsOpen, @Opened, @Resolved, @Uri, @ResolveUri, @OutlineUri, @Spec, @ParentId, @Backlog);", new {BugId = fogbugzCase.BugId, Title = fogbugzCase.Title, ProjectId = fogbugzCase.Project.Id, CategoryId = fogbugzCase.Category.Id, RootId = fogbugzCase.Root, MilestoneId = fogbugzCase.Milestone.Id, Priority = fogbugzCase.Priority, StatusId = fogbugzCase.Status.Id, EstimatedHours = fogbugzCase.EstimatedHours, ElapsedHours = fogbugzCase.ElapsedHours, PersonAssignedToId = fogbugzCase.PersonAssignedTo.Id, PersonResolvedById = fogbugzCase.PersonResolvedBy.Id, IsResolved = fogbugzCase.IsResolved, IsOpen = fogbugzCase.IsOpen, Opened = fogbugzCase.Opened, Resolved = fogbugzCase.Resolved, Uri = fogbugzCase.Uri, OutlineUri = fogbugzCase.OutlineUri, Spec = fogbugzCase.Spec, ParentId = fogbugzCase.ParentId, Backlog = fogbugzCase.Backlog});
        }
    }
}

I first tried doing the simpler way of just passing in fogbugzCase instead of the anonymous object but resulted in a different exception about CategoryId.

Anyone see what I'm missing?

Put a breakpoint and check all your objects. If I had to guess, based on what you said about the CategoryId, fogbugzCase.Category may be null. But check everything. If you access a property of a null reference, you will get a NullReferenceException. — zimdanen
– zimdanen, Commented Jun 28, 2013 at 22:30
@zimdanen thx, there was something null -- just trying to find way to check that now. — Anthony Elliott
– Anthony Elliott, Commented Jun 28, 2013 at 22:51
Almost all cases of NullReferenceException are the same. Please see "What is a NullReferenceException in .NET?" for some hints. — John Saunders
– John Saunders, Commented Jun 29, 2013 at 2:50

Marc Gravell · Accepted Answer · 2013-06-28 23:05:43Z

7

It sounds like one of the properties is null. Split the code:

var args =  new {BugId = fogbugzCase.BugId, Title = fogbugzCase.Title, ProjectId = fogbugzCase.Project.Id, CategoryId = fogbugzCase.Category.Id, RootId = fogbugzCase.Root, MilestoneId = fogbugzCase.Milestone.Id, Priority = fogbugzCase.Priority, StatusId = fogbugzCase.Status.Id, EstimatedHours = fogbugzCase.EstimatedHours, ElapsedHours = fogbugzCase.ElapsedHours, PersonAssignedToId = fogbugzCase.PersonAssignedTo.Id, PersonResolvedById = fogbugzCase.PersonResolvedBy.Id, IsResolved = fogbugzCase.IsResolved, IsOpen = fogbugzCase.IsOpen, Opened = fogbugzCase.Opened, Resolved = fogbugzCase.Resolved, Uri = fogbugzCase.Uri, OutlineUri = fogbugzCase.OutlineUri, Spec = fogbugzCase.Spec, ParentId = fogbugzCase.ParentId, Backlog = fogbugzCase.Backlog});
conn.Execute("INSERT INTO fogbugz.Cases(CaseId, Title, ProjectId, CategoryId, Root, MilestoneId, Priority, Status, EstimatedHours, ElapsedHours, AssignedTo, ResolvedBy, IsResolved, IsOpen, Opened, Resolved, Uri, ResolveUri, OutlineUri, SpecUri, ParentId, Backlog) VALUES(@BugId, @Title, @ProjectId, @CategoryId, @RootId, @MilestoneId, @Priority, @StatusId, @EstimatedHours, @ElapsedHours, @PersonAssignedToId, @PersonResolvedById, @IsResolved, @IsOpen, @Opened, @Resolved, @Uri, @ResolveUri, @OutlineUri, @Spec, @ParentId, @Backlog);", args);

It the code fails on the first line, it isn't anything to do with dapper - it didn't even get anywhere near dapper. You'll need to check all the nested members.

answered Jun 28, 2013 at 23:05

Marc Gravell

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1 Comment

Anthony Elliott Over a year ago

that worked, thx. Now I get a NotSupportedException which I just asked about here

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