实体框架核心6-多对多更新

Question

我试图在Server上为EF 6创建一个多到多的更新，但我真的很困惑。我有stock.cs类和location.cs类

public class Stock : BaseModel 
{
    public Stock()
    {
        this.Locations = new List<Location>();
    }

    [Key] 
    public int Id { get; set; }
    public string Name { get; set; } = string.Empty;
    public string Guid { get; set; } = string.Empty;
    public string RackBarNumber { get; set; } = string.Empty;
    public string ShelveNumber { get; set; } = string.Empty;
    public string ShelveName { get; set; } = string.Empty;

    public virtual List<Location>? Locations { get; set; }
}

public class Location : BaseModel
{
    public Location()
    {
        this.Stocks = new List<Stock>();
    }

    [Key] 
    public int Id { get; set; }
    public string Name { get; set; } = string.Empty;
    public string? Description { get; set; }

    public virtual List<Stock>? Stocks { get; set; }
}

我用这个作为我的DTO来获取我所有的当前位置

public class StockLocations
{
    public Stock Stock { get; set; }
    public virtual ICollection<Location> currentLocations { get; set; }
}

现在StockController是更新字段的代码，我可以在EF创建的StockLocation表中创建和删除。但是当我一次尝试许多更新的时候，它就会乱七八糟。

这是我最后一次尝试：

[HttpPut("{id}")]
public async Task<IActionResult> PutStock(int id, StockLocations stockLocation)
{
    await _userService.ConfirmUser(User);
        
    stockLocation.Stock.UpdatedAt = DateTime.Now;
        
    List<Location> removedLocations = new List<Location>();

    if (id != stockLocation.Stock.Id)
    {
        return BadRequest();
    }

    _context.Entry(stockLocation.Stock).State = EntityState.Modified;

    try
    {
        await _context.SaveChangesAsync();
            
        // Add new items to the database
        foreach (var item in stockLocation.Stock.Locations)
        {
            if (!stockLocation.currentLocations.Any(x => x.Id == item.Id))
            {
                _context.Entry(item).State = EntityState.Modified;
                await _context.SaveChangesAsync();
            }
        }
            
        // Create a list of removed locations to be removed from the database
        foreach (Location location in stockLocation.currentLocations)
        {
            if (!stockLocation.Stock.Locations.Any(x => x.Id == location.Id))
            {
                removedLocations.Add(location);
            }
        }

        foreach (var item in removedLocations)
        {
            /*
            Stock stock = _context.Stocks.Include(x => x.Locations).Single(x =>             x.Id == id);
            Location locationToDelete = stock.Locations.Find(x => x.Id == item.Id);

            stock.Locations.Remove(locationToDelete);
            await _context.SaveChangesAsync();
            */
        }
    }
    catch (DbUpdateConcurrencyException)
    {
        return NoContent();
    }

    return NoContent();
}

有谁愿意告诉我如何正确地处理这件事吗？

Answer 1

由于您需要更新StockLocations，所以我建议您只需从数据库中提取记录，例如：

        var record = await  _context.StockLocations
            .Include(a=>a.Location).Include(a=>a.Stock)
            .FirstOrDefaultAsync(a=>a.id == id);  
    
        if(record == null) {
        thrown new NotFoundException(); 
        }  
    
    stockLocation.Stock.UpdatedAt = DateTime.Now; 
     await _context.SaveChangesAsync(); 

 // other code  
 // add new location to the db if they don't exist 
 var locations = stockLocation.Location; 
  foreach(var loc in locations) {
    var findLocation = 
    _context.Locations.FirstOrDefault(a=>a.Name.ToLower() == 
   loc.Name.ToLower()) ; 
   if(findLocation == null){
  // does not exist and can be added 
   } 

}