Is it possible to convert a DataTable to IEnumerable where the T can not be defined at compile time and is not known beforehand?

Question

So I'll explain my situation first. I have a WPF View for my customer that is populated based on SQL strings that the customer defines. They can change these and add/remove these at any point and the structure of the result set is not in my control. My expected output for this is

1. Populating the DataGrid at runtime without prior knowledge of the structure so using AutoGenerateColumns and providing dataTable.DefaultView as the ItemsSource for the DataGrid. This is bound to my DataGrid.

GetItemsSource = dataTable.DefaultView;

2. Export this DataGrid to a CSV for the customer to check whenever they want.

Now I already have a Generic List function to Save to CSV but since the structure is not known I can't change my dataTable to a list to use this.

My current solution is Save To CSV function that uses a dataTable instead of a List.

Is there some other type of data structure I could use instead of dataTable that would make using my generic function possible or do I have just have an extra Save To CSV function just for this scenario?

UPDATE

My generic list function

public static void SaveToCsv<T>(List<T> data, string filePath) where T : class
        {
            CreateDirectoryIfNotExists(filePath);

            List<string> lines = new();
            StringBuilder line = new();

            if (data == null || data.Count == 0)
            {
                throw new ArgumentNullException("data", "You must populate the data parameter with at least one value.");
            }
            var cols = data[0].GetType().GetProperties();

            foreach (var col in cols)
            {
                line.Append(col.Name);
                line.Append(",");
            }

            lines.Add(line.ToString().Substring(0, line.Length - 1));

            foreach (var row in data)
            {
                line = new StringBuilder();

                foreach (var col in cols)
                {
                    line.Append(col.GetValue(row));
                    line.Append(",");
                }

                lines.Add(line.ToString().Substring(0, line.Length - 1));
            }
            System.IO.File.WriteAllLines(filePath, lines);
        }

My current Data Table function

public static void SaveToCsv(DataTable data, string filePath)
        {
            CreateDirectoryIfNotExists(filePath);

            List<string> lines = new();
            StringBuilder line = new();

            if(data == null)
            {
                throw new ArgumentNullException("data", "The DataTable has no values to Save to CSV.");
            }

            IEnumerable<string> columnNames = data.Columns.Cast<DataColumn>().Select(column => column.ColumnName);
            line.AppendLine(string.Join(",", columnNames));

            lines.Add(line.ToString().Substring(0, line.Length - 3));
            int prevlinelength = line.Length - 1;

            foreach (DataRow row in data.Rows)
            {
                IEnumerable<string> fields = row.ItemArray.Select(field => field.ToString());
                line.AppendLine(string.Join(",", fields));

                lines.Add(line.ToString().Substring(prevlinelength + 1, line.Length - 3 - prevlinelength));
                prevlinelength = line.Length - 1;
            }
            File.WriteAllLines(filePath, lines);
        }

Answer 1

Is it possible to convert a DataTable to IEnumerable where the T can not be defined at compile time and is not known beforehand?

you can create generic objects at runtime, but it is not simple, so I would avoid it if possible.

Is there some other type of data structure I could use instead of dataTable that would make using my generic function possible or do I have just have an extra Save To CSV function just for this scenario?

You could simply convert the Rows property on your datatable and convert it to a List<DataRow> and give to your function. But it would probably not do what you want.

What you need is a some way to convert a DataRow into an object of a class with properties for each column, and while it is possible to create classes from a database model, it will be a lot of work to do so at runtime. I would guess far more than your current solution.

To conclude, keep your current solution if it works. Messing around with reflection and runtime code generation will just make things more complicated.