Blazor 创建服务，从 SQL 服务器存储过程中提取数据

Question

I'm a noob when it comes to Blazor, and C# for that matter.

I'm trying to create a simple service. Simple process that includes running a stored procedure, and displaying its results in a table. I'm starting simple, by just making sure that the process runs.

Here's what my service looks like:

public class ACheckerService : IACheckerService
{
    // Database connection
    private readonly SqlConnectionConfig _config;

    public ACheckerService(SqlConnectionConfig config)
    {
        _config = config;
    }

    public async Task<IEnumerable<AChecker>> GetAllExceptions()
    {
        IEnumerable<AChecker> exceptions;

        using (var conn = new SqlConnection(_config.Value))
        {
            exceptions = await conn.QueryAsync<AChecker>("Auto.GetAll", commandType: System.Data.CommandType.StoredProcedure);
        }

        return exceptions.ToList(); ;
    }
}

I created AChecker model class which comprises of the fields that are to be pulled in by the stored procedure. Just 4 fields.

Once I had this done, I added a Blazor component ( .Razor )

This is what my code looks like:

@page "/Data/Auto"

@using AChecker.Data

@inject IACheckerService CheckerService

<h3>Auto</h3>

<p>This component demonstrates Auto Exceptions</p>

@if (aChecker is null)
{
    <p><em>Loading....</em></p>
}
else
{
    <p><em>Data....</em></p>
}

@code {
    private IEnumerable<AChecker> aChecker;

    protected override async Task OnInitializedAsync()
    {
        aChecker = await CheckerService.GetAllAutoExceptions();
    }
}

I added this service in Startup.Cs like:

services.AddSingleton<ACheckerService>();

Is there any issue with the code above or why it would not work?

I have this service added in my app, basically when I click on the menu, I expect to see either Loading or Data (ideally down the road, I want to create a table and populate the fields from the stored procedure in it, there are 4 fields), however I get a bunch of errors:

InvalidOperationException: Cannot provide a value for property CheckerService on type AChecker.Pages.MyPages.Auto. There is no registered service of type AChecker.Data.IACheckerService

Answer 1

Try registering the service using this overload instead which specifies the interface and its concrete implementation:

services.AddSingleton<IACheckerService, ACheckerService>();