EF Core - 添加具有唯一索引的数据时出现重复键错误
EF Core - error with duplicated key while adding data with unique index
我正在尝试使用 EF Core 将数据添加到数据库,但我无法克服重复键错误:Cannot insert duplicate key row in object 'dbo.Stocks' with unique index 'IX_Stocks_Name'. The duplicate key value is (stock1).
我有实体 Stock
与 Transaction
具有一对多关系 - 一个 Stock
可以与多个 Transaction
相关。
只有当数据库中没有具有给定 ID 的 Stock
时,问题才会发生 - 在这种情况下,我可以添加许多具有相同 StockID
的 Transaction
和有效:
using(var context = dbContextFactory.CreateDbContext(new string[0]))
{
List<Transaction> list = new List<Transaction>();
//If there's no Stock with ID "stock1" in the database the code works.
//Executing the code for the second time results in error, however, if I changed stock1 to stock2 it would work
var stock1 = new Stock("stock1");
list.AddRange(new Transaction[]
{
//I can add two exactly the same `Transaction`s and it's ok when executed on a fresh database
new Transaction(stock1, DateTime.Now, 1M, 5),
new Transaction(stock1, DateTime.Now, 1M, 5),
});
context.Transactions.AddRange(list);
context.SaveChanges();
}
下面我添加了 classes 及其 IEntityTypeConfiguration
s 的定义。
提前感谢您的任何提示。
Transaction
class:
public class Transaction
{
public Stock RelatedStock { get; set; }
public DateTime TransactionTime { get; set; }
public Decimal Price { get; set; }
public int Volume { get; set; }
public Transaction() { }
}
TransactionConfiguration
class:
public class TransactionConfiguration : IEntityTypeConfiguration<Transaction>
{
public void Configure(EntityTypeBuilder<Transaction> builder)
{
builder
.ToTable("Transactions");
builder
.Property<int>("TransactionID")
.HasColumnType("int")
.ValueGeneratedOnAdd()
.HasAnnotation("Key", 0);
builder
.Property(transaction => transaction.Price)
.HasColumnName("Price")
.IsRequired();
builder
.Property(transaction => transaction.TransactionTime)
.HasColumnName("Time")
.IsRequired();
builder
.Property(transaction => transaction.Volume)
.HasColumnName("Volume")
.IsRequired();
builder
.HasIndex("RelatedStockStockID", nameof(Transaction.TransactionTime))
.IsUnique();
}
}
Stock
class:
public class Stock
{
public string Name { get; set; }
public ICollection<Transaction> Transactions { get; set; }
public Stock() { }
}
StockConfiguration
class:
public class StockConfiguration : IEntityTypeConfiguration<Stock>
{
public void Configure(EntityTypeBuilder<Stock> builder)
{
builder
.ToTable("Stocks");
builder
.Property<int>("StockID")
.HasColumnType("int")
.ValueGeneratedOnAdd()
.HasAnnotation("Key", 0);
builder
.Property(stock => stock.Name)
.HasColumnName("Name")
.HasMaxLength(25)
.IsRequired();
builder
.HasMany(stock => stock.Transactions)
.WithOne(transaction => transaction.RelatedStock)
.IsRequired();
builder
.HasIndex(stock => stock.Name)
.IsUnique();
}
}
dbo.Stocks
table 上有一个名为 IX_Stocks_Name
的唯一索引。你违反了这个索引。
你的问题是这一行:
var stock1 = new Stock("stock1");
你一遍又一遍地创造 "stock1"。相反,您应该首先检索(或存储)"stock1" 的 Stock
实体并使用它(如果它已经存在)。如果它不存在,那么创建一个是安全的。
简而言之,代码正在使用现有的 Name
.
将 INSERT
转换为 dbo.Stocks
您需要检查是否有所需 ID 已知的股票。为了你的例子:
var stock1 = context.Stocks.SingleOrDefault(x => x.StockId == "stock1") ?? new Stock("stock1");
如果数据库中已有股票,这将关联现有股票,如果有 none,则关联新股票。
感谢@Zer0 和@Steve Py 的建议,我提出了以下解决方案:
void Insert(IEnumerable<Transaction> data)
{
using(var context = dbContextFactory.CreateDbContext(new string[0]))
{
List<Stock> stocks = data.Select(s => s.RelatedStock).Distinct(new StockComparer()).ToList();
context.AddRange(stocks);
context.SaveChanges();
stocks = context.Stocks.ToList();
List<Transaction> newList = new List<Transaction>(data.Count());
foreach (var t in data)
{
Stock relatedStock = stocks.Where(s => s.Name == t.RelatedStock.Name).First();
t.RelatedStock = relatedStock;
newList.Add(t);
}
context.Transactions.AddRange(newList);
context.SaveChanges();
}
}
我正在尝试使用 EF Core 将数据添加到数据库,但我无法克服重复键错误:Cannot insert duplicate key row in object 'dbo.Stocks' with unique index 'IX_Stocks_Name'. The duplicate key value is (stock1).
我有实体 Stock
与 Transaction
具有一对多关系 - 一个 Stock
可以与多个 Transaction
相关。
只有当数据库中没有具有给定 ID 的 Stock
时,问题才会发生 - 在这种情况下,我可以添加许多具有相同 StockID
的 Transaction
和有效:
using(var context = dbContextFactory.CreateDbContext(new string[0]))
{
List<Transaction> list = new List<Transaction>();
//If there's no Stock with ID "stock1" in the database the code works.
//Executing the code for the second time results in error, however, if I changed stock1 to stock2 it would work
var stock1 = new Stock("stock1");
list.AddRange(new Transaction[]
{
//I can add two exactly the same `Transaction`s and it's ok when executed on a fresh database
new Transaction(stock1, DateTime.Now, 1M, 5),
new Transaction(stock1, DateTime.Now, 1M, 5),
});
context.Transactions.AddRange(list);
context.SaveChanges();
}
下面我添加了 classes 及其 IEntityTypeConfiguration
s 的定义。
提前感谢您的任何提示。
Transaction
class:
public class Transaction
{
public Stock RelatedStock { get; set; }
public DateTime TransactionTime { get; set; }
public Decimal Price { get; set; }
public int Volume { get; set; }
public Transaction() { }
}
TransactionConfiguration
class:
public class TransactionConfiguration : IEntityTypeConfiguration<Transaction>
{
public void Configure(EntityTypeBuilder<Transaction> builder)
{
builder
.ToTable("Transactions");
builder
.Property<int>("TransactionID")
.HasColumnType("int")
.ValueGeneratedOnAdd()
.HasAnnotation("Key", 0);
builder
.Property(transaction => transaction.Price)
.HasColumnName("Price")
.IsRequired();
builder
.Property(transaction => transaction.TransactionTime)
.HasColumnName("Time")
.IsRequired();
builder
.Property(transaction => transaction.Volume)
.HasColumnName("Volume")
.IsRequired();
builder
.HasIndex("RelatedStockStockID", nameof(Transaction.TransactionTime))
.IsUnique();
}
}
Stock
class:
public class Stock
{
public string Name { get; set; }
public ICollection<Transaction> Transactions { get; set; }
public Stock() { }
}
StockConfiguration
class:
public class StockConfiguration : IEntityTypeConfiguration<Stock>
{
public void Configure(EntityTypeBuilder<Stock> builder)
{
builder
.ToTable("Stocks");
builder
.Property<int>("StockID")
.HasColumnType("int")
.ValueGeneratedOnAdd()
.HasAnnotation("Key", 0);
builder
.Property(stock => stock.Name)
.HasColumnName("Name")
.HasMaxLength(25)
.IsRequired();
builder
.HasMany(stock => stock.Transactions)
.WithOne(transaction => transaction.RelatedStock)
.IsRequired();
builder
.HasIndex(stock => stock.Name)
.IsUnique();
}
}
dbo.Stocks
table 上有一个名为 IX_Stocks_Name
的唯一索引。你违反了这个索引。
你的问题是这一行:
var stock1 = new Stock("stock1");
你一遍又一遍地创造 "stock1"。相反,您应该首先检索(或存储)"stock1" 的 Stock
实体并使用它(如果它已经存在)。如果它不存在,那么创建一个是安全的。
简而言之,代码正在使用现有的 Name
.
INSERT
转换为 dbo.Stocks
您需要检查是否有所需 ID 已知的股票。为了你的例子:
var stock1 = context.Stocks.SingleOrDefault(x => x.StockId == "stock1") ?? new Stock("stock1");
如果数据库中已有股票,这将关联现有股票,如果有 none,则关联新股票。
感谢@Zer0 和@Steve Py 的建议,我提出了以下解决方案:
void Insert(IEnumerable<Transaction> data)
{
using(var context = dbContextFactory.CreateDbContext(new string[0]))
{
List<Stock> stocks = data.Select(s => s.RelatedStock).Distinct(new StockComparer()).ToList();
context.AddRange(stocks);
context.SaveChanges();
stocks = context.Stocks.ToList();
List<Transaction> newList = new List<Transaction>(data.Count());
foreach (var t in data)
{
Stock relatedStock = stocks.Where(s => s.Name == t.RelatedStock.Name).First();
t.RelatedStock = relatedStock;
newList.Add(t);
}
context.Transactions.AddRange(newList);
context.SaveChanges();
}
}