Fastest way to save and restore datagrid view contents

Question

Hallo,

I have lots of datagrid view and all of them bound to list of objects , one example is shown below, where Qty and remarks are the input fields and not necessarily all of them will be filled. I want to save rows where there is a Qty. I dont want to save the complete row, instead only the ID , Qty and Remarks.

At present I filter the Qty in the list using LINQ and looping it and save the row contents as List of strings like this "ID/Qty/Remarks" . To restore, i split the string and restore it to the List. It works without any problem.

Is there any alternative or better approach to it in terms of performance?

Thanks

Answer 1

Hello,

The following uses a class named Product, if using a DataTable or DataSet then adjustments are needed. The code finds rows with a Qty not null (Nothing)

To save and read back a List(Of ProductSave) use Json.net (the link shows serialize and deserialize in C# but is easy enough to convert to VB, if you get stuck I can help) via this package.

Product class

Public Class Product  
    Public Property Id() As Integer  
    Public Property Description() As String  
    Public Property Qty() As Integer?  
    Public Property UnitCost() As Decimal  
  
    Public ReadOnly Property Total() As Decimal  
        Get  
            If Qty.HasValue Then  
                Return CDec(Qty * UnitCost)  
            Else  
                Return 0  
            End If  
        End Get  
  
    End Property  
  
    Public Property Remarks() As String  
  
End Class  

Class to save rows

Public Class ProductSave  
    Public Property Id() As Integer  
    Public Property Qty() As Integer?  
    Public Property Remarks() As String  
End Class  

Mock up data

Public Class MockedData  
    Public Shared Function Products() As List(Of Product)  
        Dim productList = New List(Of Product)()  
        productList.Add(New Product() With {  
                            .Id = 1,  
                            .Description = "Item1",  
                            .Qty = Nothing,  
                            .UnitCost = 2.99D,  
                            .Remarks = "Item 1 remarks"  
                            })  
        productList.Add(New Product() With {  
                            .Id = 2,  
                            .Description = "Item2",  
                            .Qty = 3,  
                            .UnitCost = 10.99D,  
                            .Remarks = "Item 2 remarks"  
                            })  
        productList.Add(New Product() With {  
                            .Id = 3,  
                            .Description = "Item3",  
                            .Qty = Nothing,  
                            .UnitCost = 10.99D,  
                            .Remarks = "Item 3 remarks"  
                            })  
        productList.Add(New Product() With {  
                            .Id = 4,  
                            .Description = "Item3",  
                            .Qty = 8,  
                            .UnitCost = 1.99D,  
                            .Remarks = "Item 4 remarks"  
                            })  
        productList.Add(New Product() With {  
                            .Id = 5,  
                            .Description = "Item3",  
                            .Qty = 8,  
                            .UnitCost = 1.99D,  
                            .Remarks = ""  
                            })  
        Return productList  
    End Function  
End Class  

Form, one DataGridView, one Button

Public Class MainForm  
    Private _bindingSource As New BindingSource()  
  
    Private Sub MainForm_Shown(sender As Object, e As EventArgs) Handles Me.Shown  
        DataGridView1.AllowUserToAddRows = False  
        _bindingSource.DataSource = MockedData.Products()  
        DataGridView1.DataSource = _bindingSource  
    End Sub  
  
    Private Sub GetRowsToSaveButton_Click(sender As Object, e As EventArgs) Handles GetRowsToSaveButton.Click  
  
        Dim results = DirectCast(_bindingSource.DataSource, List(Of Product)).  
                Where(Function(prod) prod.Qty.HasValue AndAlso Not String.IsNullOrWhiteSpace(prod.Remarks)).  
                ToList()  
  
        If results.Count <= 0 Then  
            Return  
        End If  
  
        Dim saved = New List(Of ProductSave)  
  
        For Each product In results  
            saved.Add(New ProductSave() With {.Id = product.Id, .Qty = product.Qty, .Remarks = product.Remarks})  
        Next  
    End Sub  
  
    Private Sub SaveTo(sender As List(Of ProductSave))  
        ' Save information to say a .json file using json.net NuGet package  
    End Sub  
    Private Function GetSaved() As List(Of ProductSave)  
        ' read from .json file created in SaveTo method above  
        Throw New NotImplementedException  
    End Function  
End Class  

Edit. I missed one part

Private Sub GetRowsToSaveButton_Click(sender As Object, e As EventArgs) Handles GetRowsToSaveButton.Click  
  
    Dim results = DirectCast(_bindingSource.DataSource, List(Of Product)).  
            Where(Function(prod) prod.Qty.HasValue AndAlso Not String.IsNullOrWhiteSpace(prod.Remarks)).  
            ToList()  
  
    If results.Count <= 0 Then  
        Return  
    End If  
  
    Dim saved = New List(Of ProductSave)  
  
    For Each product In results  
        saved.Add(New ProductSave() With {.Id = product.Id, .Qty = product.Qty, .Remarks = product.Remarks})  
    Next  
  
    SaveTo(saved)  
End Sub  

---

Answer 2

Is there any alternative or better approach to it in terms of performance?

No not really but you could use a more formulized approach by using Json or XML.

Answer 3

Hallo Karen,

I have following function to serialize and deserialize to xml. It works but now i dont know how i can restore the deserialize object values back into datagridview

SerializeObj(saved, "C:\temp\test.xml")

Public Sub SerializeObj(obj As Object, ByVal path As String)

        Dim ws As New XmlWriterSettings With {.NewLineHandling = NewLineHandling.Entitize}
        Dim serializer As New XmlSerializer(obj.GetType, New XmlRootAttribute("Project"))

        Using xmlWriter As XmlWriter = XmlWriter.Create(path, ws)
            serializer.Serialize(xmlWriter, obj)
        End Using

    End Sub

    Public Function deSerializeObj(obj As Object, ByVal path As String) As Object

        Try

            Dim fs As FileStream = New FileStream(path, FileMode.Open)
            Dim serializer As New XmlSerializer(obj.GetType, New XmlRootAttribute("Project"))
            obj = CType(serializer.Deserialize(fs), Object)
            fs.Close()
            Return obj

        Catch ex As Exception
            Return Nothing
        End Try

    End Function

Thanks

Answer 4

As mentioned in my initial reply, consider using a json file. I had time to take code I have in C# and convert to VB.

Requires Json.net NuGet package

Note The methods provided are generic so they will work on any class.

The following image shows the class structure in a project named JsonNetLibrary where a simple console project, JsonNetLibaryConsole uses JsonNetLibrary and yes this will work also in a Windows Form project while I used a console project to be devoured of any user interface distractions.

The following code module provides a language extension to serialize a list to a file (to use if for a single instance create another method which accepts a single instance of a class. I did a list and not a single instance as I have only so much time in my day to provide a quality response.

Imports System.IO  
Imports Newtonsoft.Json  
  
Namespace LanguageExtensions  
  
    Public Module GenericExtensions  
        Private Function SettingsDefault() As JsonSerializerSettings  
            Return New JsonSerializerSettings With {.Formatting = Formatting.Indented}  
        End Function  
  
        ''' <summary>  
        ''' Write list to json file  
        ''' </summary>  
        ''' <typeparam name="TModel"></typeparam>  
        ''' <param name="list"></param>  
        ''' <param name="fileName"></param>  
        <Runtime.CompilerServices.Extension>  
        Public Sub ModeListToJson(Of TModel)(list As List(Of TModel), fileName As String)  
  
            JsonConvert.DefaultSettings = AddressOf SettingsDefault  
  
            Dim json = JsonConvert.SerializeObject(list)  
  
            File.WriteAllText(fileName, json)  
  
        End Sub  
    End Module  
End Namespace  

This class provide a deserialize process.

Imports System.IO  
Imports Newtonsoft.Json  
  
Namespace Classes  
  
    Public Class Helpers  
        ''' <summary>  
        ''' Read model from json file  
        ''' </summary>  
        ''' <typeparam name="TModel"></typeparam>  
        ''' <param name="fileName"></param>  
        ''' <returns></returns>  
        Public Shared Function ReadFromJson(Of TModel)(fileName As String) As List(Of TModel)  
            Dim model As New List(Of TModel)()  
  
            If File.Exists(fileName) Then  
                Dim json = File.ReadAllText(fileName)  
                model = JsonConvert.DeserializeObject(Of List(Of TModel))(json)  
            End If  
            Return model  
        End Function  
    End Class  
End Namespace  

In the console project

Public Class Person  
    Public Property FirstName() As String  
    Public Property LastName() As String  
End Class  

Mockup some data

Public Class Mocked  
    Public Shared Function People() As List(Of Person)  
        Return New List(Of Person) From {  
            New Person() With {.FirstName = "Karen", .LastName = "Payne"},  
            New Person() With {.FirstName = "Katrina", .LastName = "Payne"}  
            }  
    End Function  
End Class  

Use it

Imports System.IO  
Imports JsonNetLibrary.Classes  
Imports JsonNetLibrary.LanguageExtensions  
  
Module Module1  
  
    Sub Main()  
        Dim fileName = "People.json"  
  
        Console.ForegroundColor = ConsoleColor.Yellow  
        Console.WriteLine("Saving list to file")  
        Console.ResetColor()  
        Mocked.People().ModeListToJson(fileName)  
  
        Console.WriteLine(New String("-"c, 40))  
  
        Dim json = File.ReadAllText(fileName)  
  
        Console.ForegroundColor = ConsoleColor.Yellow  
        Console.WriteLine("View list from file")  
        Console.ResetColor()  
        Console.WriteLine(json)  
  
        Dim results As List(Of Person) = Helpers.ReadFromJson(Of Person)(fileName)  
  
        Console.ForegroundColor = ConsoleColor.Yellow  
        Console.WriteLine("Read back file to list of person")  
        Console.ResetColor()  
        Console.WriteLine(New String("-"c, 40))  
  
        For Each person As Person In results  
            Console.WriteLine($"{vbTab}{person.FirstName} {person.LastName}")  
        Next  
        Console.ReadLine()  
    End Sub  
End Module  

---