Get data from MySQL server in ASP.NET Core

Question

I'm working on a ASP.NET Core MVC Project which connects to a MySQL database. I've successfully been able to create items in the database, but I'm having trouble retrieving data.

My startup.cs looks like this:

public void ConfigureServices(IServiceCollection services)
{
        // Add framework services.
        services.AddMvc();
        services.AddScoped<ISqlService, SqlService>();
        services.AddDbContext<WebAPIDataContext>(options => options.UseMySQL(Configuration.GetConnectionString("MySqlServer")));
}

My controller for retrieving data looks like this:

public IActionResult Index()
{
    var model = new ItemsViewModel();
    model.items = _sqlService.GetAllItems();

    return View(model);
}

My Service (EF) looks like this:

public IEnumerable<Item> GetAllItems()
{
    return _webAPIDataContext.items;
}

My html looks like this:

    <table class="table table-hover">
    <thead>
        <tr>
            <th>Id</th>
            <th>Headline</th>
            <th>Category</th>
            <th>Description</th>
            <th>Picture URL</th>
            <th></th>
        </tr>
    </thead>

    @foreach (var item in Model.items) {
        <tr>
            <td>@item.items_id</td>
            <td>@item.items_headline</td>
            <td>@item.items_category</td>
            <td>@item.items_description</td>
            <td>@item.items_picture</td>
            <td>
                <div class="pull-right">
                    <a href="/items/edit/@item.items_id" class="btn btn-default">Edit</a>
                    <a href="/items/remove/@item.items_id" class="btn btn-danger">Delete</a>
                </div>
            </td>
        </tr>
    }
</table>

I'm pretty new in C# / ASP.NET Core so it might be a small thing why this is not working.

If I omit the foreach statement in the html file I don't get any errors, and the page renders.

This is the error being thrown in the console:

Microsoft.AspNetCore.Diagnostics.ExceptionHandlerMiddleware[0]

An unhandled exception has occurred: Method not found: 'Void Microsoft.EntityFrameworkCore.Query.QueryContextFactory..ctor(Microsoft.EntityFrameworkCore.ChangeTracking.Internal.IStateManager, Microsoft.EntityFrameworkCore.Internal.IConcurrencyDetector, Microsoft.EntityFrameworkCore.ChangeTracking.Internal.IChangeDetector)'. System.MissingMethodException: Method not found: 'Void Microsoft.EntityFrameworkCore.Query.QueryContextFactory..ctor(Microsoft.EntityFrameworkCore.ChangeTracking.Internal.IStateManager, Microsoft.EntityFrameworkCore.Internal.IConcurrencyDetector, Microsoft.EntityFrameworkCore.ChangeTracking.Internal.IChangeDetector)'.

at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
at Microsoft.Extensions.DependencyInjection.ServiceLookup.CallSiteRuntimeResolver.VisitConstructor(ConstructorCallSite constructorCallSite, ServiceProvider provider)

Answer 1

Managed to solve it.

I got this error while using the "MySql.Data.EntityFrameworkCore": "7.0.6-IR31". But my error was that i was pulling in the "Microsoft.EntityFrameworkCore.Relational":"1.1.0" or "Microsoft.EntityFrameworkCore":"1.1.0" in addition to the mysql nuget. But the "Microsoft.EntityFrameworkCore.Relational":"1.1.0" is pulled by the mysql nugget so all you have to do is to remove the "Microsoft.EntityFrameworkCore.Relational":"1.1.0" and/or "Microsoft.EntityFrameworkCore1.1.0" from your project.json and it will make your project great again.

Answer 2

I think you should use the Pomelo or the Sapient Guardian provider rather than this pre release version from MySQL.

https://docs.microsoft.com/en-us/ef/core/providers/sapient-guardian/

https://docs.microsoft.com/en-us/ef/core/providers/pomelo/