Rest API 数据不删除

Question

I working on a simple crud operation on API. My GET, POST, PUT all are working fine. But the DELETE method doesn't work. It show a error message:

The DELETE statement conflicted with the REFERENCE constraint "FK_Configurations_Mobiles_MobileId". The conflict occurred in database "TestPrime2", table "dbo.Configurations", column 'MobileId'.

Here Mobile class and Configurations class their relation one-to-many.

[Route("api/[controller]")]
[ApiController]
public class MobilesController : ControllerBase
{
    private readonly TestContext _context;

    public MobilesController(TestContext context)
    {
        _context = context;
    }

    [HttpGet]
    public async Task<ActionResult<IEnumerable<Mobile>>> GetMobiles()
    {
        return await _context.Mobiles.Include(p => p.Configuration).ToListAsync();
    }

    [HttpGet("{id}")]
    public async Task<ActionResult<Mobile>> GetMobile(int id)
    {
        if(id <= 0)
        {
            return BadRequest();
        }

        var mobile = await _context.Mobiles
            .Include(p => p.Configuration)
            .Where( x => x.Id == id).FirstOrDefaultAsync();

        if (mobile == null)
        {
            return NotFound();
        }

        return mobile;
    }

    [HttpPut("{id}")]
    public async Task<IActionResult> PutMobile(int id, Mobile mobile)
    {
        if (id != mobile.Id)
        {
            return BadRequest();
        }

        _context.Entry(mobile).State = EntityState.Modified;

        try
        {
            await _context.SaveChangesAsync();
        }
        catch (DbUpdateConcurrencyException)
        {
            if (!MobileExists(id))
            {
                return NotFound();
            }
            else
            {
                throw;
            }
        }

        return NoContent();
    }

    [HttpPost]
    public async Task<ActionResult<Mobile>> PostMobile(Mobile mobile)
    {
        _context.Mobiles.Add(mobile);
        await _context.SaveChangesAsync();

        return CreatedAtAction("GetMobile", new { id = mobile.Id }, mobile);
    }

    [HttpDelete("{id}")]
    public async Task<IActionResult> DeleteMobile(int id)
    {
        if(id <= 0)
        {
            return BadRequest();
        }

        var mobile = await _context.Mobiles.FindAsync(id);

        if (mobile == null)
        {
            return NotFound();
        }

        _context.Mobiles.Remove(mobile);
        await _context.SaveChangesAsync();

        return NoContent();
    }

    private bool MobileExists(int id)
    {
        return _context.Mobiles.Any(e => e.Id == id);
    }
}

All methods work fine without the DELETE method

Answer 1

You need to remove all entries with the MobileId from Configurations table first.

It would be something like this:

 _context.RemoveRange(_context.Configurations.Where(x => x.MobileId == id).ToList());

And then you can delete the Mobile from the Mobile table.

Answer 2

Its because the Foreign key MobileId in your table named TestPrime2 has a reference to the row you're trying to delete.

If you delete that row in the TestPrime2 table which has the MobileId you're trying to delete it will work.