Binding value from cell to cell using DataGrid of WPF

Question

0.00/5 (No votes)

See more:

I have an issue when binding value dynamic from cell to cell using DataGrid of WPF. Let me explain my expectation first. I want to create a DataGrid like that:

Quantity | Prices | Pay
(user input) | (user input ) | (auto calculate and display Pay = Quantity * Prices )
the code behide work correctly. But the GUI is not updated. Could you please support me to resolve this issue?

Here is my XAML:

HTML

<grid>
    <datagrid x:name="DGTest" itemssource="{Binding m_Products}" horizontalalignment="Left" margin="40,80,0,0" verticalalignment="Top" height="134" width="414" xmlns:x="#unknown">
              AutoGenerateColumns="False">
        <datagrid.columns>
            <datagridtextcolumn binding="{Binding Quantity, UpdateSourceTrigger=LostFocus}" header="Quantity" width="60" />
            <datagridtextcolumn binding="{Binding Prices, UpdateSourceTrigger=LostFocus}" header="Prices" width="60" />
            <datagridtextcolumn binding="{Binding Pay, UpdateSourceTrigger=LostFocus}" header="Pay" width="60" isreadonly="True" />
        </datagrid.columns>
    </datagrid>

</grid>

Here is my code behide:

C#

MainWindow : Window
{
    ObservableCollection<product> m_Products = new ObservableCollection<product>();
    private class PRODUCT : INotifyPropertyChanged
    {
        int _quantity;
        public int Quantity
        {
            get { return _quantity;  }
            set
            {
                if (_quantity != value)
                {
                    _quantity = value;
                    _pay = _quantity * _prices;
                }
            }
        }
        int _prices;
        public int Prices
        {
            get{ return _prices;  }
            set
            {
                if (_prices != value)
                {
                    _prices = value;
                    _pay = _quantity * _prices;
                }
            }
        }
        int _pay;
        public int Pay
        {
            get { return _pay; }
            set
            {
                if (_pay != value)
                {
                    _prices = value;
                    _pay = _quantity * _prices;
                }
            }
        }
        void OnPropertyChanged(string prop)
        {               
            if (PropertyChanged != null)
                PropertyChanged(this, new PropertyChangedEventArgs(prop));
        }
        public event PropertyChangedEventHandler PropertyChanged;
    }
    public MainWindow()
    {

        InitializeComponent();

        m_Products.Add(new PRODUCT { Quantity = 10, Prices = 20, Pay = 200 });
        m_Products.Add(new PRODUCT { Quantity = 2, Prices = 20, Pay = 40 });

        DGTest.ItemsSource = m_Products;

        DataContext = this;
    }
}

Posted 14-Sep-14 22:24pm

DangBao

Updated 14-Sep-14 22:27pm

v2

Add a Solution

1 solution

Add a Solution

Add your solution here

Treat my content as plain text, not as HTML

Preview 0

…

Existing Members

Sign in to your account

...or Join us

Download, Vote, Comment, Publish.

Your Email
Password
Forgot your password?

Your Email
This email is in use. Do you need your password?
Optional Password

I have read and agree to the Terms of Service and Privacy Policy
Please subscribe me to the CodeProject newsletters

When answering a question please:

Read the question carefully.
Understand that English isn't everyone's first language so be lenient of bad spelling and grammar.
If a question is poorly phrased then either ask for clarification, ignore it, or edit the question and fix the problem. Insults are not welcome.
Don't tell someone to read the manual. Chances are they have and don't get it. Provide an answer or move on to the next question.

Let's work to help developers, not make them feel stupid.

This content, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)

Pheonyx · Accepted Answer · 2014-09-14T22:32:00

I would suggest you replace your product class with the following:

C#

private class PRODUCT : INotifyPropertyChanged
    {
        int _quantity;
        public int Quantity
        {
            get { return _quantity;  }
            set
            {
                if (_quantity != value)
                {
                    _quantity = value;
                    OnPropertyChanged("Quantity");
                    OnPropertyChanged("Pay");
                }
            }
        }
        int _prices;
        public int Prices
        {
            get{ return _prices;  }
            set
            {
                if (_prices != value)
                {
                    _prices = value;
                    OnPropertyChanged("Prices");
                    OnPropertyChanged("Pay");
                }
            }
        }
        int _pay;
        public int Pay
        {
            get { return _quantity * _prices; }
                        
        }
        void OnPropertyChanged(string prop)
        {
            if (PropertyChanged != null)
                PropertyChanged(this, new PropertyChangedEventArgs(prop));
        }
        public event PropertyChangedEventHandler PropertyChanged;
    }

I would also change this binding by removing the update attribute as below:

XML

<datagridtextcolumn binding="{Binding Pay}" header="Pay" width="60" isreadonly="True" />

As for an explanation, at no point were you telling your GUI to update. To have to call your "OnPropertyChanged" event with the name of the properties that have been updated. When you have a lot of calculated properties this can be a pain, although there are advised solutions around that allow you to partially automate that process.