分组时如何在LINQ查询中添加索引？

Question

I have the following LINQ statement that works

     var separator = new[] { " ||| " };
        var objectives = data.Select(s => s.Split(separator, StringSplitOptions.RemoveEmptyEntries))
            .GroupBy(strings => strings[0])
            .Select(grouping => new Objective
            {
                Text = grouping.Key,
                ObjectiveDetails = grouping.Select(s => new ObjectiveDetail { 
                    Text = s[1]
                }).ToList()
            })
            .ToArray();
        return objectives;
    }

What I would like to do is to populate a field called Number inside the Objective object and a field called Number inside the ObjectiveDetail object. I want the number to start at one and be incremented so each new Objective and ObjectiveDetail inside gets a new number assigned to it. I tried to do the following:

     var separator = new[] { " ||| " };
        var objectives = data.Select(s => s.Split(separator, StringSplitOptions.RemoveEmptyEntries))
            .GroupBy(strings => strings[0])
            .Select(grouping, index => new Objective
            {
                Number = grouping.Index,
                Text = grouping.Key,
                ObjectiveDetails = grouping.Select(s, index => new ObjectiveDetail { 
                    Number = index,
                    Text = s[1]
                }).ToList()
            })
            .ToArray();
        return objectives;
    }

This gives me an error on the .Select(grouping, line saying "The name grouping does not exist". Can someone help tell me how I can fix this and add an index to the GroupBy ?

Answer 1

我相信您对于具有两个参数的lambda只是语法错误： .Select((groupings, index) => expression)