How to convert a nested list to a dataset in C #

Question

I have a nested list and I need to convert it to a DataSet in C #. I found many examples about this, but they do not do what I need. I have a list in a list, I need a nested list in another DataTable in a DataSet.

Here is an example list

public class InvoiceResponse(){ public string BillToName { get; set; } public string BillToAddr1 { get; set; } ... ... public List<InvoiceItemResponse> Items { get; set; } } 

I used the code below to convert a list to a DataSet, but it did not convert the items in a DataTable to a DataSet

 public DataSet CreateDataSet<T>(List<T> list) { //list is nothing or has nothing, return nothing (or add exception handling) if (list == null || list.Count == 0) { return null; } //get the type of the first obj in the list var obj = list[0].GetType(); //now grab all properties var properties = obj.GetProperties(); //make sure the obj has properties, return nothing (or add exception handling) if (properties.Length == 0) { return null; } //it does so create the dataset and table var dataSet = new DataSet(); var dataTable = new DataTable(); //now build the columns from the properties var columns = new DataColumn[properties.Length]; for (int i = 0; i < properties.Length; i++) { columns[i] = new DataColumn(properties[i].Name, properties[i].PropertyType); } //add columns to table dataTable.Columns.AddRange(columns); //now add the list values to the table foreach (var item in list) { //create a new row from table var dataRow = dataTable.NewRow(); //now we have to iterate thru each property of the item and retrieve it value for the corresponding row cell var itemProperties = item.GetType().GetProperties(); for (int i = 0; i < itemProperties.Length; i++) { dataRow[i] = itemProperties[i].GetValue(item, null); } //now add the populated row to the table dataTable.Rows.Add(dataRow); } //add table to dataset dataSet.Tables.Add(dataTable); //return dataset return dataSet; } 

How to convert a list of Items to another DataTable in a DataSet?

Answer 1

You can simply add a little recursion to your code, something like this:

 var set = new DataSet(); AddToDataSet(set, resp); ... public static void AddToDataSet(DataSet set, object value) { if (set == null) throw new ArgumentNullException(nameof(set)); if (value == null) return; var type = value.GetType(); var table = set.Tables[type.FullName]; if (table == null) { // create one table per type (name) table = new DataTable(type.FullName); set.Tables.Add(table); foreach (var prop in type.GetProperties().Where(p => p.CanRead)) { if (IsEnumerable(prop)) continue; var col = new DataColumn(prop.Name, prop.PropertyType); table.Columns.Add(col); } } var row = table.NewRow(); foreach (var prop in type.GetProperties().Where(p => p.CanRead)) { object propValue = prop.GetValue(value); if (IsEnumerable(prop)) { if (propValue != null) { foreach (var child in (ICollection)propValue) { AddToDataSet(set, child); } } continue; } row[prop.Name] = propValue; } table.Rows.Add(row); } private static bool IsEnumerable(PropertyInfo pi) { // note: we could also use IEnumerable (but string, arrays are IEnumerable...) return typeof(ICollection).IsAssignableFrom(pi.PropertyType); }