WPF_Practice/PacticeSolution/MSSQL_MVVM_Sample/ViewModel/MainViewModel.cs

using MSSQL_MVVM_Sample.Database;
using MSSQL_MVVM_Sample.Model;
using MSSQL_MVVM_Sample.Structure;
using System;
using System.Collections.Generic;
using System.Collections.ObjectModel;
using System.ComponentModel;
using System.Data;
using System.Linq;
using System.Runtime.CompilerServices;
using System.Text;
using System.Threading.Tasks;
using System.Windows;
using System.Windows.Input;
using System.Windows.Interop;

namespace MSSQL_MVVM_Sample.ViewModel
{
    internal class MainViewModel : INotifyPropertyChanged
    {
        private Student _student;

        public event PropertyChangedEventHandler? PropertyChanged;

        public MainViewModel()
        {
            _student = new Student();
            SqlManager.Instance.ConnectionString = "Data Source=peacecloud.synology.me,21433;Initial Catalog=Study;User ID=study;Password=Study1234";
        }

        public string Name
        {
            get { return _student.Name; }
            set
            {
                _student.Name = value;
                OnPropertyChanged(nameof(this.Name));
            }
        }

        public int Age
        {
            get { return _student.Age; }
            set
            {
                _student.Age = value;
                OnPropertyChanged(nameof(this.Age));
            }
        }

        public string Grade
        {
            get { return _student.Grade; }
            set
            {
                _student.Grade = value;
                OnPropertyChanged(nameof(this.Grade));
            }
        }

        public int Score
        {
            get { return _student.Score; }
            set
            {
                _student.Score = value;
                OnPropertyChanged(nameof(this.Score));
            }
        }

        private ObservableCollection<Student> _sampleData;
        public ObservableCollection<Student> SampleData
        {
            get
            {
                if (_sampleData == null)
                    _sampleData = new ObservableCollection<Student>();

                return _sampleData;
            }
            set { _sampleData = value; }
        }

        private ICommand _connectCommand;
        public ICommand ConnectCommand
        {
            get { return _connectCommand ?? (_connectCommand = new DelegateCommand(ConnectDatabase)); }
        }

        private ICommand _searchCommand;
        public ICommand SearchCommnad
        {
            get { return _searchCommand ?? (_searchCommand = new DelegateCommand(SearchData)); }
        }

        private void ConnectDatabase()
        {
            if (!SqlManager.Instance.GetConnection())
            {
                MessageBox.Show("Fail to connect to database", "Error");
                return;
            }

            MessageBox.Show("Success to connect to database", "Inform");
        }

        private void SearchData()
        {
            if (this.SampleData != null)
                this.SampleData.Clear();

            string query = @"SELECT * FROM Student";

            DataSet ds = SqlManager.Instance.ExecuteSelectQuery(query);
            if (ds == null || ds.Tables.Count < 1 || ds.Tables[0].Rows == null || ds.Tables[0].Rows.Count < 1)
            {
                MessageBox.Show("No data in table", "Alert");
                return;
            }

            foreach (DataRow row in ds.Tables[0].Rows)
            {
                Student student = new Student()
                {
                    Name = row["Name"].ToString(),
                    Age = (int)row["Age"],
                    Grade = row["Grade"].ToString(),
                    Score = (int)row["Score"]
                };

                this.SampleData.Add(student);
            }
        }

        private void OnPropertyChanged([CallerMemberName] string propertyName = null)
        {
            this.PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
        }
    }
}