Hello World Console App with XPO and .NET
- 4 minutes to read
This tutorial demonstrates how to create an XPO-based .NET console application, which initializes the data layer and performs basic data operations.
Tip
The complete .NET sample project is available at https://github.com/DevExpress/XPO/tree/master/Tutorials/Console.
You can find more XPO tutorials in the Getting Started with XPO topic.
Prerequisites
Install the .NET SDK and runtime.
Create a Project
Open the system console and execute the following command to create a new C# project (you can substitute MyXpoApp with your project name):
dotnet new console -o MyXpoApp
To create a VB.NET project, add the -lang vb switch to the command above.
Get XPO from NuGet
Install the DevExpress.Xpo NuGet package.
cd MyXpoApp
dotnet add package DevExpress.Xpo
Install the Database Provider
Use the following command to install the Microsoft.Data.Sqlite package and use the local SQLite database:
dotnet add package Microsoft.Data.Sqlite
You can use any other .NET compatible provider XPO supports (see Database Systems Supported by XPO).
Define the Data Model
Edit the MyXpoApp/Program.cs(vb) file (or add a new code file to the project) and implement the following StatisticInfo persistent class with the Key, Info, and Date properties. The class is mapped to the StatisticInfo table with the Key, Info, and Date columns.
using DevExpress.Xpo;
// ...
public class StatisticInfo : XPLiteObject {
public StatisticInfo(Session session)
: base(session) {
}
Guid key;
[Key(true)]
public Guid Key {
get { return key; }
set { SetPropertyValue(nameof(Key), ref key, value); }
}
string info;
[Size(255)]
public string Info {
get { return info; }
set { SetPropertyValue(nameof(Info), ref info, value); }
}
DateTime date;
public DateTime Date {
get { return date; }
set { SetPropertyValue(nameof(Date), ref date, value); }
}
}
Setup the Data Layer
In the Program.cs(vb) file, change the Program.Main method. Pass the connection string to the XpoDefault.GetDataLayer method and assign the created IDataLayer object to the XpoDefault.DataLayer property.
using System.IO;
using DevExpress.Xpo;
using DevExpress.Xpo.DB;
// ...
class Program {
static void Main(string[] args) {
string appDataPath = Environment.GetFolderPath(Environment.SpecialFolder.ApplicationData);
string connectionString = SQLiteConnectionProvider.GetConnectionString(Path.Combine(appDataPath, "myXpoApp.db"));
XpoDefault.DataLayer = XpoDefault.GetDataLayer(connectionString, AutoCreateOption.DatabaseAndSchema);
}
}
Make CRUD Operations With Data
Use the UnitOfWork API to execute create, read, update, and delete (CRUD) operations. For example, you can add the following code after the data layer initialization:
using System.Linq;
using DevExpress.Xpo;
// ...
// Create data:
Console.WriteLine($"Type some text to create a new 'StatisticInfo' record.");
string userInput = Console.ReadLine();
using (UnitOfWork uow = new UnitOfWork()) {
StatisticInfo newInfo = new StatisticInfo(uow);
newInfo.Info = userInput;
newInfo.Date = DateTime.Now;
uow.CommitChanges();
}
// Read data:
Console.WriteLine($"Your text is saved. The 'StatisticInfo' table now contains the following records:");
using (UnitOfWork uow = new UnitOfWork()) {
var query = uow.Query<StatisticInfo>()
.OrderBy(info => info.Date)
.Select(info => $"[{info.Date}] {info.Info}");
foreach (var line in query) {
Console.WriteLine(line);
}
}
// Delete data:
using (UnitOfWork uow = new UnitOfWork()) {
var itemsToDelete = uow.Query<StatisticInfo>().ToList();
Console.Write($"Records count is {itemsToDelete.Count}. Do you want to delete all records (y/N)?: ");
if (Console.ReadLine().ToLowerInvariant() == "y") {
uow.Delete(itemsToDelete);
uow.CommitChanges();
Console.WriteLine($"Done.");
}
}
Save the changes in the Program.cs file and run the application. Use the dotnet run command in the system console to start the console application.
Note
Refer to the Deploy .NET Applications topic for information on how to deploy your application.