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Service Logic

Service Logic executes on create, read, update or delete of an entity.

Service classes can be added to the Project.Services/Logic folder.

Logic Stage

Service Logic can execute at the listed stages below.

  • PreOperation: After security validation and before the save to the database
  • PostOperation: After the save to the database

Create Service Logic

To create Service Logic, create a new file in the Project.Services project in the ServiceLogic folder.

Project.Services / Logic / MyEntityService.cs

// The ServiceLogic attribute specifies what table this will execute on, what operation(s), and when (before or after the transaction)
[ServiceLogic(nameof(MyEntity), DataOperation.Create | DataOperation.Update, LogicStage.PreOperation, 100)]
public class MyEntityService : IServiceLogic
{
    public async Task<Response<object?>> Execute(ServiceContext context)
    {
        if (context.DataOperation is DataOperation.Create)
        {
            // Do something on Create
        }


        if (context.DataOperation is DataOperation.Update)
        {
            // Do something on Update
        }


        return ServiceResult.Success();
    }
}

The ServiceLogic attribute takes the following parameters.

  • TableName: The name of the entity the service logic will execute on. '*' for all entities.
  • DataOperations: Flags that determine what data operations this should execute on, create, read, update, and delete.
  • LogicStages: Flags that determine which stages the service logic should exeucte on, PreOperation, or PostOperation.
  • Order: Service Logic classes executing on the same table, data operation, and logic stage, will execute following the order.

ServiceContext

ServiceContext has a number of properties that can be used during execution.

Project.Services / Logic / MyEntityService.cs

[ServiceLogic(nameof(MyEntity), DataOperation.Create | DataOperation.Update | DataOperation.Read, LogicStage.PreOperation | LogicStage.PostOperation, 100)]
public class MyEntityService : IServiceLogic
{
    public async Task<Response<object?>> Execute(ServiceContext context)
    {
        // Get the db context
        DataContext db = context.GetDbContext<DataContext>();


        // Do something on Create or Update
        if (context.DataOperation is DataOperation.Create or DataOperation.Update)
        {
            // If this is an update, PreEntity is populated with the entity before the update
            MyEntity preEntity = context.GetPreEntity<MyEntity>();
            // The Entity property will have the latest values to be saved to the database
            MyEntity entity = context.GetEntity<MyEntity>()


            // Do something before the SaveChanges call
            if (context.LogicStage is LogicStage.PreOperation)
            {
                // If the Name field is being updated (always true on Create)
                if (context.ValueChanged(nameof(MyEntity.Name)))
                {


                }
            }


            // Do something after the SaveChanges call
            // On create if we need the id of the record being saved
            if (context.LogicStage is LogicStage.PostOperation)
            {


            }
        }


        // Do something on Read
        if (context.DataOperation is DataOperation.Read)
        {
            // Get the query that was sent to the api
            ReadInput readInput = context.ReadInput;
        }


        return ServiceResult.Success();
    }
}

Modify Records

Use the Create, Update, and Delete methods of the ServiceContext to modify records. While it is possible to modify records directly using the Entity Framework DbContext, using the ServiceContext ensures that the service logic is executed.

Project.Services / Logic / MyEntityService.cs

[ServiceLogic(nameof(MyEntity), DataOperation.Create | DataOperation.Update, LogicStage.PreOperation, 100)]
public class MyEntityService : IServiceLogic
{
    public async Task<Response<object?>> Execute(ServiceContext context)
    {
        // Get the db context
        DataContext db = context.GetDbContext<DataContext>();
        List<Widget> widgets = await db.Widgets.ToListAsync();


        // Update the price of all Widgets
        foreach (Widget widget in widgets)
        {
            widget.Price = 9.99M;
            // Update the Widget and trigger any service logic
            await context.Update<Widget>(widget);
        }


        return ServiceResult.Success();
    }
}

Performance

For optimal performance, prioritize using PreOperation logic whenever possible. This allows the database save to be delayed until all records are processed, or until an entity with PostOperation logic is triggered.

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