使用 Dapper 插入时出现 NullReferenceException

Question

当我运行以下代码时，我得到一个 NullReferenceException 说对象引用未设置为对象的实例。我已经使用不太复杂但格式相同的对象成功插入了 dapper，所以我不确定我做错了什么。

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});
        }
    }
}

我首先尝试使用更简单的方法，只传入 fogbugzCase 而不是匿名对象，但导致 CategoryId 出现不同的异常。

有人知道我错过了什么吗？

Answer 1

听起来其中一个属性是null。拆分代码：

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);

如果代码在第一行失败，它与 dapper 没有任何关系 - 它甚至没有接近 dapper。您需要检查所有嵌套成员。