linq简化

Question

如何简化代码?

Answer 1

isMe 改成这样，看行不？

isMe = ((user==null)?false:(user.UId==c.UId))

请问你的.Net Framework 是哪个版本？我写了个 demo 怎么没问题：

public partial class Form1 : Form {
    public Form1() {
        InitializeComponent();
    }

    private void button1_Click(object sender, EventArgs e) {
    }

    private void Form1_Load(object sender, EventArgs e) {
        BuilCommentList(null, 0);
    }

    public List<CommentForPictureDetail> BuilCommentList(UserForIndex user, int pId) {
        List<Comment> comments = new List<Comment>();
        comments.AddRange(new Comment[]{
            new Comment(){
                CId = 1,
                UId = 1,
                Content = "hello",
                UserInfo = new UserInfo{UId = 1, UserName = "tom"},
                PostDate = DateTime.Now
            },
            new Comment(){
                CId = 2,
                UId = 1,
                Content = "world",
                UserInfo = new UserInfo{UId = 1, UserName = "alice"},
                PostDate = DateTime.Now
            }
        });

        List<CommentForPictureDetail> cList = new List<CommentForPictureDetail>();

        cList = comments.Select(c => new CommentForPictureDetail() {
            cId = c.CId,
            cUId = c.UId,
            content = c.Content,
            isMe = ((user == null) ? false : (user.UId == c.UId)),
            username = c.UserInfo.UserName,
            postDate = c.PostDate
        }).ToList();

        return cList;
    }
}

public class UserForIndex {
    public int UId {
        get;
        set;
    }
}

public class CommentForPictureDetail {
    public int cId {
        get;
        set;
    }

    public int cUId {
        get;
        set;
    }

    public string content {
        get;
        set;
    }

    public bool isMe {
        get;
        set;
    }

    public string username {
        get;
        set;
    }

    public DateTime postDate {
        get;
        set;
    }
}

public class Comment {
    public int CId {
        get;
        set;
    }

    public int UId {
        get;
        set;
    }

    public string Content {
        get;
        set;
    }

    public UserInfo UserInfo {
        get;
        set;
    }

    public DateTime PostDate {
        get;
        set;
    }
}

public class UserInfo {
    public int UId {
        get;
        set;
    }
    public string UserName {
        get;
        set;
    }
}

Answer 2

哈哈哈哈我终于懂了,这里要用动态的方式构造Lambda,就是一直创建Expression类的方式造一个lambda表达式

Answer 3

int? userid = user == null ? null : user.userid;
…
isme = uid == userid,