實體框架更新查找表正在將項目添加到另一個表

Question

查詢表有問題。 我有一個表格，可以讓我從團隊的列表中選擇顏色。 更新方法如下所示：

[HttpPut]
[Route("")]
/// <summary>
/// Update a team
/// </summary>
/// <param name="model">The team model</param>
/// <returns>Nothing</returns>
public async Task<IHttpActionResult> Update(TeamBindingViewModel model)
{

    // If our model is invalid, return the errors
    if (!ModelState.IsValid)
        return BadRequest(ModelState);

    // Get our current team
    var team = await this.service.GetAsync(model.Id, "Colours");

    // Make changes to our team
    team.Name = model.Name;
    team.Sport = model.Sport;

    // Find out which colours need adding and removing
    var coloursToRemove = GetDifference(team.Colours, model.Colours);
    var coloursToAdd = GetDifference(model.Colours, team.Colours);

    // Loop through our colours to remove and remove them
    if (coloursToRemove.Count() > 0)
        foreach (var colour in coloursToRemove)
            team.Colours.Remove(colour);

    // Loop through the colours to add and add them
    if (coloursToAdd.Count() > 0)
        foreach (var colour in coloursToAdd)
            team.Colours.Add(colour);

    // Update the team
    this.service.Update(team);

    // Save the database changes
    await this.unitOfWork.SaveChangesAsync();

    // Return Ok
    return Ok(model);
}

private IList<Colour> GetDifference(IList<Colour> firstList, IList<Colour> secondList)
{

    // Create a new list
    var list = new List<Colour>();

    // Loop through the first list
    foreach (var first in firstList)
    {

        // Create a boolean and set to false
        var found = false;

        // Loop through the second list
        foreach (var second in secondList)
        {

            // If the first item id is the same as the second item id
            if (first.Id == second.Id)
            {

                // Mark it has being found
                found = true;
            }
        }

        // After we have looped through the second list, if we haven't found a match
        if (!found)
        {

            // Add the item to our list
            list.Add(first);
        }
    }

    // Return our differences
    return list;
}

如果我在unitOfWork.SaveChangesAsync（）上設置一個斷點，那么我可以看到團隊顏色正在使用數據庫中已經存在的現有顏色（所有ID都匹配。但是一旦執行SaveChangesAsync ，它就會在Colors中創建一個新行與我剛剛選擇的顏色重復的表格，我不希望它創建新的行，我希望它使用選擇的顏色。

我不確定如何提供更多信息； 我希望這足以為某人提供幫助的描述！

更新

因此，我決定查看生成的SQL。 我的“ 顏色”表中有一個看起來像這樣的顏色 ：

10紅色（Pms200）ff0000

因此， Id為10 ， 名稱為Red（Pms200） ， 十六進制為ff0000 。 如果我在編輯團隊時選擇該顏色，然后按提交。 它運行上面顯示的Update方法，並且通過在構造函數中添加以下行，我更改了DbContext來記錄sql：

this.Database.Log = s => Debug.WriteLine(s);

因此，當執行SaveChangesAsync代碼時，將生成以下SQL：

Started transaction at 13/04/2015 12:25:03 +01:00

UPDATE [dbo].[Teams]
SET [Name] = @0, [Sport] = @1
WHERE ([Id] = @2)

-- @0: 'Testing' (Type = String, Size = -1)

-- @1: 'ultimate-frisbee' (Type = String, Size = -1)

-- @2: '1' (Type = Int32)

-- Executing asynchronously at 13/04/2015 12:25:03 +01:00

-- Completed in 5 ms with result: 1



INSERT [dbo].[Colours]([Name], [Hex])
VALUES (@0, @1)
SELECT [Id]
FROM [dbo].[Colours]
WHERE @@ROWCOUNT > 0 AND [Id] = scope_identity()


-- @0: 'Red (Pms200)' (Type = String, Size = -1)

-- @1: 'ff0000' (Type = String, Size = -1)

-- Executing asynchronously at 13/04/2015 12:25:03 +01:00

-- Completed in 1 ms with result: SqlDataReader



INSERT [dbo].[TeamColours]([TeamId], [ColourId])
VALUES (@0, @1)

-- @0: '1' (Type = Int32)

-- @1: '43' (Type = Int32)

-- Executing asynchronously at 13/04/2015 12:25:03 +01:00

-- Completed in 1 ms with result: 1



Committed transaction at 13/04/2015 12:25:03 +01:00

Closed connection at 13/04/2015 12:25:03 +01:00

現在的問題是，它應該只在TeamColours表中插入內容，而不是在Colors表中插入內容。 我不知道為什么...

由於有人要求查看我的UnitOfWork類，因此它是：

public class UnitOfWork<TContext> : IUnitOfWork where TContext : DbContext, new()
{
    private readonly DbContext context;
    private Dictionary<Type, object> repositories;

    public DbContext Context { get { return this.context; } }

    public UnitOfWork()
    {
        this.context = new TContext();
        repositories = new Dictionary<Type, object>();
    }

    public IRepository<TEntity> GetRepository<TEntity>() where TEntity : class
    {
        if (repositories.Keys.Contains(typeof(TEntity)))
            return repositories[typeof(TEntity)] as IRepository<TEntity>;

        var repository = new Repository<TEntity>(context);

        repositories.Add(typeof(TEntity), repository);

        return repository;
    }

    public async Task SaveChangesAsync()
    {
        try
        {
            await this.context.SaveChangesAsync();
        }
        catch (DbUpdateConcurrencyException ex)
        {
            ex.Entries.First().Reload();
        }
    }

    public void Dispose()
    {
        this.context.Dispose();
    }
}

盡管我確定這不是導致問題的原因。

Answer 1

嘗試這個

public async Task<IHttpActionResult> Update(TeamBindingViewModel model)
{
    // If our model is invalid, return the errors
    if (!ModelState.IsValid)
        return BadRequest(ModelState);

    // Get our current team
    var team = await this.service.GetAsync(model.Id, "Colours");

    // Make changes to our team
    team.Name = model.Name;
    team.Sport = model.Sport;

    //remove
    foreach (var colour in team.Colours.ToList())
    {
        if (!model.Colours.Any(c => c.Id == colour.Id))
            team.Colours.Remove(colour);
    }

    //add
    foreach (var colour in model.Colours)
    {
        if (!team.Colours.Any(c => c.Id == colour.Id))
            team.Colours.Add(colour);
    }

    // Update the team
    this.service.Update(team);

    // Save the database changes
    await this.unitOfWork.SaveChangesAsync();

    // Return Ok
    return Ok(model);
}

Answer 2

Model.Colors沒有關聯上下文。 因此，您的Db上下文會嘗試添加新的。

1-從存儲庫獲取顏色

var newColours = repository.ListColours(model.Colors.Select(m=>m.Id));  

2-為團隊分配新顏色

team.Colours = newColours;

this.service.Update(team);

await this.unitOfWork.SaveChangesAsync();

EF將自動執行刪除和添加操作。

我尚未測試此代碼。 但是我希望EntityFramework可以比我想象的更聰明。