无法将日期时间转换为字符串

Question

I have a database with some dates, i want to fetch them and convert them into a string[] to use in a graph.

        var Yaxis = db.Graphs
                    .Where(x => x.Node.Contains(Node))
                    .Select(x => x.Dates)
                    .ToArray();


        var data = new string[Yaxis.Length];
        for (int i = 0; i < Yaxis.Length ; i++)
        {
            data[i] = Yaxis[i].ToString;
        }

The .ToString do not work here with a "non-delegate type"-error. I dont know any other way to parse the array to a string[].

Any idea?

Answer 1

data[i] = Yaxis[i].ToString();

When you don't include the parentheses, the compiler will assume you're talking about the function ToString , when you're actually talking about the return value.

When you're talking about the function itself, it's called a delegate (kind of similar to a function pointer in C/C++), which explains the error you're getting.

Answer 2

As Antonijn posted, the immediate problem is that you're using ToString without actually calling the method.

However, you can do better than this to start with by doing it in LINQ:

var data = db.Graphs
             .Where(x => x.Node.Contains(Node))
             .Select(x => x.Dates.ToString())
             .ToArray();

Note that we're calling ToString() in the projection here. If that doesn't give the result you want (eg because it performs the conversion in the database) you can split it into two Select calls, with an AsEnumerable call forcing the second one to execute locally:

var data = db.Graphs
             .Where(x => x.Node.Contains(Node))
             .Select(x => x.Dates)
             .AsEnumerable()
             .Select(x => x.ToString())
             .ToArray();

This will use the default string representation of DateTime in the current culture, of course. You may want to consider specifying a standard or custom date/time format string to change the output format, and maybe even a different culture... it depends on what you're going to do with the data.

All of this assumes that you don't need Yaxis for anything else. If you do need Yaxis , you can still use LINQ to simplify your code:

var data = Yaxis.Select(x => x.ToString()).ToArray();