ISqlModelMapper.LoadAllByPageAsync<TModel>(int currentIndex, int pageSize, CancellationToken cancellationToken) Method

.NET Standard 2.x

Asynchronously retrieves data starting from a specified row according to the SQL query (without the Where clause) defined by the primary table in a TModel class.

Namespace: SnapObjects.Data

Assembly: SnapObjects.Data.dll

Syntax

public Task<ILoadable<TModel>> LoadAllByPageAsync<TModel>(int currentIndex, int pageSize, CancellationToken cancellationToken)

Type Parameters

TModel

The type of a model class.

Parameters

currentIndex System.Int32

The zero-based index number of the first row.

pageSize System.Int32

The number of rows per page.

cancellationToken CancellationToken

A cancellation token that can be used by other objects or threads to receive notice of cancellation.

Returns

Task<ILoadable<TModel>>

Returns a task that represents the asynchronous operation.

Remarks

If the SQL query defined in TModel makes query from multiple tables, this method only retrieves and loads data from the primary table.

Examples

The following code example demonstrates how to asynchronously load the specified page according to the SQL query (without the Where clause) defined by the Department class. It uses a CancellationTokenSource type parameter to make this operation cancelable.

using System;
using System.Collections.Generic;
using System.Threading;
using System.Threading.Tasks;
using Appeon.ApiDoc.Models.School;

namespace Appeon.ApiDoc.ISqlModelMapperExamples
{
    public class LoadAllByPageAsyncExample
    {
        private readonly SchoolContext _context;
        
        public LoadAllByPageAsyncExample(SchoolContext dataContext)
        {
            // Sets the data context.
            _context = dataContext;
        }

        public async Task<IList<Department>> Example2(CancellationTokenSource cts)
        {
            var mapper = _context.SqlModelMapper;
            
            IList<Department> deptsPage1 = null;
            
            try 
            {
                // Asynchronously loads the first page only (2 records per page)
                // If a task has been cancelled, the call to the ISqlModelMapper.LoadAllByPageAsync 
                // method throws an OperationCanceledException.
                deptsPage1 = (await mapper.LoadAllByPageAsync<Department>(0, 2, cts.Token)).ToList();
                
                Console.WriteLine("Departments (Page 1):");
                foreach (var department in deptsPage1)
                {
                    Console.WriteLine(department.Name);
                }    
            }
            catch (OperationCanceledException e)
            {
                // The operation was cancelled before completion.
                Console.WriteLine(e.Message);
            }
            catch (Exception e)
            {
                Console.WriteLine(e.Message);
            }
            finally
            {
                cts.Dispose();
            }
            
            return deptsPage1;
            
            /* The code produces the following output:
            
                A task was canceled.
            */
        }
    }
}

Applies to

.NET Standard

2.x