C# 在实体框架4中处理异常
我需要一种使用实体框架LINQ来区分SQL异常的方法,例如,当我从DbUpdateException得到的只是大量嵌套的内部异常和无用的长错误消息时,如何区分foreing键约束冲突和unique约束冲突?是否有任何较低级别的异常,我可以在其中执行类似“Catch FKException”的操作;捕获“uniqueException”或类似内容。C# 在实体框架4中处理异常,c#,sql,entity-framework,C#,Sql,Entity Framework,我需要一种使用实体框架LINQ来区分SQL异常的方法,例如,当我从DbUpdateException得到的只是大量嵌套的内部异常和无用的长错误消息时,如何区分foreing键约束冲突和unique约束冲突?是否有任何较低级别的异常,我可以在其中执行类似“Catch FKException”的操作;捕获“uniqueException”或类似内容。试试看 try { //code }
试试看
try
{
//code
}
catch (System.Data.Entity.Validation.DbEntityValidationException e)
{
string rs = "";
foreach (var eve in e.EntityValidationErrors)
{
rs = string.Format("Entity of type \"{0}\" in state \"{1}\" has the following validation errors:", eve.Entry.Entity.GetType().Name, eve.Entry.State);
Console.WriteLine(rs);
foreach (var ve in eve.ValidationErrors)
{
rs += "<br />" + string.Format("- Property: \"{0}\", Error: \"{1}\"", ve.PropertyName, ve.ErrorMessage);
}
}
throw new Exception(rs);
}
{
//代码
}
捕获(System.Data.Entity.Validation.DbEntityValidationException e)
{
字符串rs=“”;
foreach(e.EntityValidationErrors中的变量eve)
{
rs=string.Format(“状态为“{1}\”的类型为“{0}\”的实体存在以下验证错误:”,eve.Entry.Entity.GetType().Name,eve.Entry.state);
控制台写入线(rs);
foreach(eve.ValidationErrors中的变量ve)
{
rs+=“
”+string.Format(“-Property:\“{0}\”,错误:\“{1}\”,ve.PropertyName,ve.ErrorMessage);
}
}
抛出新异常(rs);
}
使用sql错误代码
catch (DbUpdateException ex)
{
var sqlex = ex.InnerException.InnerException as SqlException;
if (sqlex != null)
{
switch (sqlex.Number)
{
case 547: throw new ExNoExisteUsuario("No existe usuario destino."); //FK exception
case 2627:
case 2601:
throw new ExYaExisteConexion("Ya existe la conexion."); //primary key exception
default: throw sqlex; //otra excepcion que no controlo.
}
}
throw ex;
}
我为此编写了两个实用程序方法:
public static class DbUtils
{
/// <summary>
/// Takes a code block that updates database, runs it and catches db exceptions. If the caught
/// exception is one of those that are ok to ignore (okToIgnoreChecks) then no
/// exception is raised and result is returned. Otherwise an exception is rethrown.
///
/// This function is intended to be run within an explicit transaction, i.e.:
/// using (var transaction = db.Database.BeginTransaction()), which should be committed/rolledback afterwards.
/// Otherwise, if you don't use a transaction discard the db context or in other words make this operation
/// the only one that you run within implicit transaction.
///
/// This function can wrap a single DB statement, but it's more efficient to wrap multiple statements
/// so that locks are held for shorter period of time.
/// If an exception occurs within a transaction and is caught by this function, all other changes
/// will be still saved to DB on commit if transaction is used.
/// </summary>
/// <typeparam name="T">Any result returned by the code block</typeparam>
/// <param name="context">Database connection</param>
/// <param name="dbCodeBlock">
/// Code block to execute that updates DB. It's expected, but not critical that
/// this code does not throw any other exceptions. Do not call SaveChanges() from the code block itself. Let this
/// function do it for you.
/// </param>
/// <param name="okToIgnoreChecks">
/// List of functions that will check if an exception can be ignored.
/// </param>
/// <returns>Returns number of rows affected in DB and result produced by the code block</returns>
public static Tuple<int, T> IgnoreErrors<T>(DbContext context,
Func<T> dbCodeBlock, params Func<DbUpdateException, bool>[] okToIgnoreChecks)
{
var result = dbCodeBlock();
try
{
var rowsAffected = context.SaveChanges();
return Tuple.Create(rowsAffected, result);
}
catch (DbUpdateException e)
{
if (okToIgnoreChecks.Any(check => check(e)))
return Tuple.Create(0, result);
throw;
}
}
public static bool IsDuplicateInsertError(DbUpdateException e)
{
return GetErrorCode(e) == 2601;
}
public static bool IsForeignKeyError(DbUpdateException e)
{
return GetErrorCode(e) == 547;
}
public static T UpdateEntity<T>(DbContext context, T entity, Action<T> entityModifications)
where T : class
{
return EntityCrud(context, entity, (db, e) =>
{
db.Attach(e);
entityModifications(e);
return e;
});
}
public static T DeleteEntity<T>(DbContext context, T entity)
where T : class
{
return EntityCrud(context, entity, (db, e) => db.Remove(e));
}
public static T InsertEntity<T>(DbContext context, T entity)
where T : class
{
return EntityCrud(context, entity, (db, e) => db.Add(e));
}
public static T EntityCrud<T>(DbContext context, T entity, Func<DbSet<T>, T, T> crudAction)
where T : class
{
return crudAction(context.Set<T>(), entity);
}
}
不会引发任何异常
与前面的示例类似,但显式处理FK冲突异常:
try
{
var numInserted = DbUtils.IgnoreErrors(_db, () => DbUtils.InsertEntity(_db, someEntity), DbUtils.IsDuplicateInsertError).Item1;
// no FK exception, but maybe unique index violation, safe
// to keep going with transaction
}
catch (DbUpdateException e)
{
if (DbUtils.IsForeignKeyError(e))
{
// you know what to do
}
throw; // rethrow other db errors
}
最终,如果您有显式事务,您可以调用commit transaction,否则已在上下文中调用save。通常内部异常将包含数字错误代码,您是否尝试过查找这些错误代码?在你的问题中发布一个异常示例,确保突出显示文本并单击
{}
按钮以使其格式良好。如果你真的想友好,最后一行应该是抛出新异常(rs,e)
,这样链上的下一个人可以检查内部异常并查看堆栈跟踪等等。(也可以抛出一个自定义异常,而不是一个通用的异常
),但实际上我需要区分它们,我需要根据数据库错误的类型抛出不同的异常。
try
{
var numInserted = DbUtils.IgnoreErrors(_db, () => DbUtils.InsertEntity(_db, someEntity), DbUtils.IsDuplicateInsertError).Item1;
// no FK exception, but maybe unique index violation, safe
// to keep going with transaction
}
catch (DbUpdateException e)
{
if (DbUtils.IsForeignKeyError(e))
{
// you know what to do
}
throw; // rethrow other db errors
}