c＃csv使用第三列排序列表

Question

I have a program that opens a CSV file using StreamReader and creates a table with 4 columns and rows for however many rows are in the CSV file. This works correctly as is creating the output of:

Item Code, Item Description, Current Count, On Order

A0001, Toy Car, 4, Yes

A0002, Toy Truck, 1, No

I save all the data from the CSV file in a global list without splitting each line. When I am creating the table I split the lines using "Split(',')", which works as needed at the time. However I am unsure how to reorder the whole list using the Current Count column from largest to smallest. I have tried the following but it give an error on the Split(',').

public static class Globals
{
    public static List<string> items = new List<string>();
}
private void createTableWithOrder(int order)
{
    for (int i = 0; i < Globals.items.; i++)
    {
         var values = Globals.items[i].Split(',');

         if (order == 1)
         {
              values = Globals.items[i].OrderBy(itemDesc => itemDesc.Split(',')).ToList();
         }
    }
}

The Error given is below:

'char' does not contain a definition for 'Split' and no extension method 'Split' accepting a first argument of type 'char' could be found (are you missing a using directive or an assembly reference?)

Answer 1

The OrderBy call is working on all characters in the string at Globals.items[i] . That is why you're seeing the current error. In order to sort the entire collection the order by needs to be made on the list as a whole, eg:

var values = Globals.items.Select(line => line.Split(',')); // Select columns for all rows
var orderedListOfValues = values
    .OrderByDescending(cols => int.TryParse(cols[2].Trim(), out var order) ? order : int.MaxValue); // Sort  by count as an integer

Note that in the above example sorting on non-numeric values (eg heading) will use the maximum value of an integer. Depending on the expected outcome, these results can then be merged back into a list of strings for presentation:

var orderedItems = string.Join(",", orderedListOfValues)

Cheers!

Answer 2

The way you have stored the list will not help you to generate a table with sorting capability. To solve your problem instead of List<string> you should create a model(IItem interface and Item class) using those models create List. Then before rendering the table you can sort the List on whatever column you like.

List<IItem> items = new List<Item>();
items.Add({itemCode: excelData.itemCode , itemDescription: excelData.itemDescription,itemCount: excelData.itemCount, orderCount:excelData.orderCount});
List<IItem> itemsToCreateTable = items.OrderBy(o=>o.itemCount).ToList();

Answer 3

It is no clear why you would not simply make a “Class” of the items in the file. With a “Class” you can sort the items any way you choose and in numerous ways. In addition, it appears the column you want to sort by (Current Count) is a NUMBER. If you sort numbers as strings , you will get all the 1's together, 2's together etc. Example it would look something like.

1

10

100

2

20

3

4 …

You will not get the proper NUMERICAL sort order using strings. Therefore, you must sort the column by the number and not the string to get the correct numerical order. The idea behind using a class is it gives you full control over the sorting. If you make a List of Item and the Item class implements the IComparable interface, the sorting could be done with one line of code… Items.Sort().

Below is an example of what is described above. First the “Class” Item to hold the objects in the file. It contains only the properties need for this example, namely the CompareTo method which will get used when you call Items.Sort().

public class Item : IComparable {

  public string Code { get; set; }
  public string Description { get; set; }
  public int Count { get; set; }
  public bool OnOrder { get; set; }

  public Item(string code, string description, int count, bool onOrder) {
    Code = code;
    Description = description;
    Count = count;
    OnOrder = onOrder;
  }

  public int CompareTo(object obj) {
    Item that = (Item)obj;
    return Count.CompareTo(that.Count);
  } 
}

Below is an example of using the Item class to SORT the list by the “Current Count” column. A DataGridView is used to display the sorted list.

List<Item> Items;

public Form1() {
  InitializeComponent();
}

private void Form1_Load(object sender, EventArgs e) {
  Items = GetData();
  Items.Sort();
  dataGridView1.DataSource = Items;
}

private List<Item> GetData() {
  List<Item> items = new List<Item>();
  Item newItem;
  string line;
  using (StreamReader sr = new StreamReader(@"D:\Test\Test22.csv")) {
    while ((line = sr.ReadLine()) != null) {
      if ((newItem = GetItemFromString(line)) != null) {
        items.Add(newItem);
      }
    }
  }
  return items;
}

private Item GetItemFromString(string itemString) {
  string[] splitArray = itemString.Split(',');
  bool onOrder;
  int count = 0;
  if (splitArray.Length >= 4) {
    int.TryParse(splitArray[2].Trim(), out count);
    if (splitArray[3].Trim() == "Yes")
      onOrder = true;
    else
      onOrder = false;
    return new Item(splitArray[0].Trim(), splitArray[1].Trim(), count, onOrder);
  }
  return null;
}

Hope this helps.

Answer 4

Not a direct answer to your question. But I think you are writing code that is already available for free.

I strongly suggest that you use nuget package CSV Helper . It takes any text stream, string, text reader etc, and converts the CSV file into an IEnumerable of the type that you expect. It works with and without a header line containing the columns

class MyItem
{
    public string Code {get; set;}
    public string Description {get; set;}
    public int Count {get; set;}
    public bool OnOrder {get; set;}
}

Getting all MyItems from the CSV file:

string myCsvFileName = ...
using (TextReader reader = new StreamReader(myCsvFileName))
{
    using (var csv = new CsvReader(reader))
    {    
        IEnumerable<MyItem> items = reader.GetRecords<MyItem>();

        // you can do any Linq with this:
        var allItems = items.ToList();

        // or if you only need some records:
        var unAvailableItems = items.Where(item => item.Count == 0);
    }
}

Read the link to see what to do if you have a special separator, a header line, or anything else. It is highly configurable.