我有一个 System.InvalidOperationException: Collection was modified 错误，你可以在这里看到控制台的输出。
这是我的代码，我删除了很多行，以便结构更易于阅读。
static public void searchCode2(Dictionary<string, string> MList)
{
using (SqlConnection connection3 = new SqlConnection(ConfigurationManager.ConnectionStrings["DB"].ConnectionString))
{
connection3.Open();
SqlCommand command2 = new SqlCommand(null, connection3);
var keysWithMatchingValues = MList.Where(p => Equals(p.Value, "0")).Select(p => p.Key);
// ce for devrait macher, meme s'il y plusieurs requetes
// Tthe fallowing line is where the error point out.
foreach (var key in keysWithMatchingValues)
{
Console.WriteLine(" missing list");
string[] motToCut = key.ToString().Split(' ');
Dictionary<string, int> MoviesListMissing = new Dictionary<string, int>();
Dictionary<string, string> MoviesListMissingCode = new Dictionary<string, string>();
Dictionary<string, DateTime> MoviesListMissingDate = new Dictionary<string, DateTime>();
//// on va chercher si un des elements du dico n'a pas été récupéré.
command2.CommandText = "";
int counter = 0;
foreach (string word_cutted in motToCut)
{
// on considere que les mots qui ont plus d'une lettre
if (word_cutted.Length > 1)
{
command2.CommandText += "select Code, Titre, Date from Data where Titre LIKE '%" + word_cutted + "%';";
counter++;
Console.WriteLine("word_cutted : {0} ", word_cutted);
}
}
command2.Prepare(); // Calling Prepare after having set the Commandtext and parameters.
SqlDataReader reader2 = command2.ExecuteReader();
try
{
for (int i = 0; i < counter; i++)
{
//CODES
}
bool MoviesListMissingisEmpty = (MoviesListMissing.Count == 0);
if (!MoviesListMissingisEmpty)
{
//CODES
}
// liste le dictionnaire
foreach (string key2 in MList.Keys)
{
Console.WriteLine("Last version : {0}, {1} ", key2, MList[key2]);
}
}
catch (Exception e)
{
//Console.WriteLine("{0} Exception caught.", e);
Console.WriteLine("Last version : {0}", e);
}
finally
{
// Always call Close when done reading.
reader2.Close();
}
}
connection3.Close();
// THIS WON'T PRINT
Console.WriteLine(" Avant var key in keysWithMatchingValues ");
}
}
出于某种原因，我放了什么
connection3.Close();
不起作用，我无法弄清楚原因。在一些类似的主题中，据说使用了锁定功能，但我不知道在哪里。（我尝试了一些地方，但没有奏效）。
如果可能有帮助，这是完整的代码：
static public void searchCode2(Dictionary<string, string> MList)
{
using (SqlConnection connection3 = new SqlConnection(ConfigurationManager.ConnectionStrings["DistriDBEntities2"].ConnectionString))
{
connection3.Open();
SqlCommand command2 = new SqlCommand(null, connection3);
DateTime today = DateTime.Now;
bool pbBool = false;
string motFinal = "";
var keysWithMatchingValues = MList.Where(p => Equals(p.Value, "0")).Select(p => p.Key);
//Where(p => p.Value == "a").Select(p => p.Key);
// ce for devrait macher, meme s'il y plusieurs requetes
foreach (var key in keysWithMatchingValues)
{
pbBool = true;
Console.WriteLine(" missing list");
//literaltest.Text += "<br/>" + motFinal + ", original: " + key + "<br/>";
string[] motToCut = key.ToString().Split(' ');
Dictionary<string, int> MoviesListMissing = new Dictionary<string, int>();
Dictionary<string, string> MoviesListMissingCode = new Dictionary<string, string>();
Dictionary<string, DateTime> MoviesListMissingDate = new Dictionary<string, DateTime>();
//// on va chercher si un des elements du dico n'a pas été récupéré.
command2.CommandText = "";
int counter = 0;
foreach (string word_cutted in motToCut)
{
// on considere que les mots qui ont plus d'une lettre
if (word_cutted.Length > 1)
{
command2.CommandText += "select Code, Titre, Date from Data where Titre LIKE '%" + word_cutted + "%';";
counter++;
Console.WriteLine("word_cutted : {0} ", word_cutted);
}
}
command2.Prepare(); // Calling Prepare after having set the Commandtext and parameters.
//literaltest.Text += "<br/> on rentre dans le try apres word_cutted : ";
SqlDataReader reader2 = command2.ExecuteReader();
try
{
int resultCounter = 1;
bool resultUnique = false;
string bontitre = "";
for (int i = 0; i < counter; i++)
{
if (i == 0)
{
while (reader2.Read())
{
//literaltest.Text += "<br/> si i = 0 ";
if (reader2[1].ToString().Length > 0)
{
if (!MoviesListMissing.ContainsKey(reader2[1].ToString()))
{
//literaltest.Text += "<br/> i = 0 mot : " + reader2[0].ToString() + "," + reader2[1].ToString();
MoviesListMissing.Add(reader2[1].ToString(), 0);
MoviesListMissingCode.Add(reader2[1].ToString(), reader2[0].ToString());
bontitre = reader2[1].ToString();
resultCounter++;
if (reader2[2].ToString().Length > 0)
{
DateTime dt = Convert.ToDateTime(reader2[2].ToString());
//literaltest.Text += "<br/> date Conversion orginal:" + reader2[2].ToString() + " new : " + dt.ToString("dd/MM/yyyy");
MoviesListMissingDate.Add(reader2[1].ToString(), dt);
}
}
}
}
}
else if (!resultUnique)
{
// on réinitialise le compteur
resultCounter = 1;
reader2.NextResult();
while (reader2.Read())
{
if (reader2[1].ToString().Length > 0)
{
//literaltest.Text += "<br/> i : " + i + " mot : " + reader2[0].ToString() + "," + reader2[1].ToString();
if (!MoviesListMissing.ContainsKey(reader2[1].ToString()))
{
MoviesListMissing.Add(reader2[1].ToString(), 0);
MoviesListMissingCode.Add(reader2[1].ToString(), reader2[0].ToString());
MoviesListMissingDate.Add(reader2[1].ToString(), Convert.ToDateTime(reader2[2].ToString()));
bontitre = reader2[1].ToString();
}
else
{
//on incremente le nombre de point.
MoviesListMissing[reader2[1].ToString()] += 1;
bontitre = reader2[1].ToString();
}
resultCounter++;
}
}
}
if (resultCounter == 2)
{
// si on a eu qu'un retour lors d'une requete pour un mot alors c'est la bonne
resultUnique = true;
Console.WriteLine("ResultUnique true");
//break;
}
}
bool MoviesListMissingisEmpty = (MoviesListMissing.Count == 0);
if (!MoviesListMissingisEmpty)
{
if (resultUnique == false)
{
// liste le dictionnaire
int keyMax = 0;
string trueKey = MoviesListMissing.Keys.First();
string falseKey = "";
bool unique = true;
// on regarde quel titre a le plus de point.
foreach (string cle in MoviesListMissing.Keys)
{
if (MoviesListMissing[cle] > keyMax)
{
keyMax = MoviesListMissing[cle];
trueKey = cle;
unique = true;
falseKey = "";
}
else if (MoviesListMissing[cle] == keyMax)
{
unique = false;
falseKey += cle + ", ";
}
}
Console.WriteLine("Le bon titre est : {0} ", trueKey);
Console.WriteLine("Le bon titre est unique ? : {0} falsekey: {1}", unique.ToString(), falseKey);
// si le nombre max est détenue par un seul titre
if (unique)
{
bontitre = trueKey;
// on rajoute le code
MList[key.ToString()] = MoviesListMissingCode[trueKey];
}
else
// on regarde la date
{
string[] CuttedByDate = falseKey.ToString().Split(' ');
DateTime bestDate = MoviesListMissingDate[CuttedByDate[0]];
bontitre = CuttedByDate[0];
foreach (string wordDate in CuttedByDate)
{
if ((Math.Abs(today.Subtract(MoviesListMissingDate[CuttedByDate[0]]).Days)) < Math.Abs(today.Subtract(bestDate).Days))
{
bontitre = wordDate;
}
}
}
}
else
{
Console.WriteLine("Le bon titre trouvé de maniere unique : {0} ", bontitre);
MList[key.ToString()] = MoviesListMissingCode[bontitre];
}
}
// liste le dictionnaire
foreach (string key2 in MList.Keys)
{
Console.WriteLine("Last version : {0}, {1} ", key2, MList[key2]);
}
}
catch (Exception e)
{
//Console.WriteLine("{0} Exception caught.", e);
Console.WriteLine("Last version : {0}", e);
}
finally
{
// Always call Close when done reading.
reader2.Close();
}
}
connection3.Close();
Console.WriteLine(" Avant var key in keysWithMatchingValues ");
}
}