BlazorOdataClient 0.0.1.9

Blazor Odata Client

This client library provides virtualization to an ODATA endpoint. This library extends the existing <Virtualize> component built into .net 6.

Package Manager

Install-Package BlazorOdataClient -Version 0.0.1.9

Client Program.cs

using BlazorOdataClient;

builder.Services.AddOdataClient(httpClientName: "ConsumerApp.ServerAPI");

Usage:

@using BlazorOdataClient

<OdataVirtualize @ref="view"
                 TItem="WeatherForecast"
                 EndPoint="WeatherForecast"
                 QueryString="$OrderBy=Date desc"
                 OverscanCount="4">

    <tr>
        <td>@context.Date.LocalDateTime.ToShortDateString()</td>
        <td>@context.TemperatureC</td>
        <td>@context.TemperatureF</td>
        <td>@context.Summary</td>
    </tr>

</OdataVirtualize>

Parameters:

Endpoint used:

[Authorize]
[ApiController]
[Route(template: "api/[controller]")]
public class WeatherForecastController : ControllerBase
{
    private readonly ApplicationDbContext dbContext;
    public WeatherForecastController(ApplicationDbContext dbContext) => this.dbContext = dbContext;

    [HttpGet]
    [EnableQuery]
    public IQueryable<WeatherForecast> Get() => dbContext.WeatherForecasts;
}

Note: the use of the IQueryable. This allows the query to be passed directly to the database engine. The benefit of this is often overlooked. Database engines are designed to sort, filter, query data. dbContext.WeatherForecasts is of type DbSet<WeatherForecast> which implements IQueryable<>

Server Program.cs

builder.Services.AddControllers().AddOData(options => options
    .Select().Filter().OrderBy().SetMaxTop(maxTopValue: 100).SkipToken().Count()
    .AddRouteComponents(routePrefix: "odata", OdataConfig.GetEdmModel()));

For the component to work the Edm approach is required. The following configures the WeatherForecast odata endpoint to the WeatherForecast API.

public static class OdataConfig
{
    public static IEdmModel GetEdmModel()
    {
        var odataBuilder = new ODataConventionModelBuilder();
        odataBuilder.EntitySet<WeatherForecast>(name: "WeatherForecast");
        return odataBuilder.GetEdmModel();
    }
}

I have tested this with 100,000 records and the performance was impressive.

Migrations and Seeding the demonstration app.

To rebuild the scripts I perform the following steps.

1. Delete the database (close existing connections).
2. Delete the Migrations folder under \Data
3. Re-create the migration scripts From the package manager console: (making sure ConsumerApp.Server is the default project)

Add-Migration CreateInitialSchema -OutputDir Data/Migrations

4. Update the database

Update-Database

This statement

builder.Services.AddOdataClient(httpClientName: "ConsumerApp.ServerAPI");

adds the following services for injection

public interface IOdataClientFactory
{
    IOdataService<T> Create<T>(string endPoint);
    IOdataService<T> Create<T>(string httpClientName, string endPoint);
}

public interface IOdataService<TItem>
{
    ValueTask<OdataResponce<TItem>> GetOdataResponceAsync(string query);
    ValueTask<int> GetItemCountAsync(string queryString = "");
    ValueTask<ItemsProviderResult<TItem>> OdataPageAsync(ItemsProviderRequest request, string queryString);
}