Linq查询中未加入的数据不会输出到json中，只有出现在2个类中的相关数据才显示

Question

The basis of this question is from this question:

Combine 2 classes with adding data and 1 table has a colllection list of the other table and wanting to use linq to display

In which I "thought" the problem was solved.

However as I added in a new object to the List, now this join query does not output it

reportData.Add(new ReportData() {ReportGroupId = 3, ReportGroupName = "Straggler", SortOrder = 3, Type = 1});


var reports = reportDefinition.GroupBy(r=>r.ReportGroupId);
    var query = reportData.Join(reports, d => d.ReportGroupId, gr => gr.Key, 
                                (r,gr) => new
                                {
                                  r.ReportGroupName,
                                  items = gr.ToList(),
                                  r.ReportGroupId
                                });

Here is the dotNetFiddle https://dotnetfiddle.net/IIBFKG

Why doesn't the item that I added to the ReportData not show up? Is it the type of JOIN in Linq?

Answer 1

I think the linked question was not answered correctly.

Looks like all you need is a simple Group Join :

var query = 
    from d in reportData
    join r in reportDefinition on d.ReportGroupId equals r.ReportGroupId into items
    select new
    {
        d.ReportGroupName,
        items = items.ToList(),
        d.ReportGroupId
    };