この例外が Linq コードでポップアップすることについて、こちらの投稿のいくつかを見てきましたが、どれも役に立ちませんでした。どこかでnull値を参照していることを意味していることは承知していますが、エラーを防ぐifステートメントを設定しました。
私がやろうとしているのは、CRM データベースにクエリを実行することですが、クエリを実行した連絡先ごとに 3 つの情報のみを返します。foreach 行で例外が発生します。これが私のコードです（まあ、実際には私のすべてではありません）：
class Program
{
private static List<account> accs = new List<account>();
private static List<CrmContact> cnts = new List<CrmContact>();
static void Main(string[] args)
{
if (!CRMConnectionHelper.Authenticate()) throw new Exception("Authentication on CRM Server was NOT successful.");
Console.WriteLine("Authentication on CRM Server was successful.");
GetAllAccounts();
GetActiveContacts();
QueryDB();
}
private static void QueryDB()
{
var m = from c in cnts
select new
{
acct = c.ParentAccount.name,
last = c.Contact.lastname,
first = c.Contact.firstname
};
List<string> lines = new List<string>();
try
{
foreach (var c in m) **Exception here**
{
if (c != null)
{
//string sub = c1.first.PadRight(10).Substring(0, 3); // Object ref ex here.
lines.Add(string.Format("{0}\t{1}\t{2}", c.acct, c.last, c.first));
Console.WriteLine(c.acct);
System.Threading.Thread.Sleep(100);
}
else
{
Console.WriteLine("c is null. continuing.");
continue;
}
}
Console.WriteLine("Writing list contents to .txt ...");
System.IO.File.WriteAllLines(@"C:\Documents and Settings\paldrich\Desktop\lines1.txt", lines.ToArray());
Console.WriteLine("Finished. Press ENTER to exit.");
Console.ReadLine();
}
catch (Exception ex)
{
Console.WriteLine(String.Format("Error: {0}", ex));
}
}
private static void GetAllAccounts()
{
ColumnSet colsAcc = new ColumnSet { Attributes = new string[] { "accountid", "name", "statecode" } };
QueryExpression accountQuery = new QueryExpression { EntityName = EntityName.account.ToString(), ColumnSet = colsAcc };
BusinessEntityCollection accounts = CRMConnectionHelper.crmService.RetrieveMultiple(accountQuery);
Console.WriteLine(String.Format("Total number of accounts {0}", accounts.BusinessEntities.Length));
for (int i = 0; i < accounts.BusinessEntities.Length; i++) { accs.Add((account)accounts.BusinessEntities[i]); }
}
private static void GetActiveContacts()
{
try
{
ColumnSet cols = new ColumnSet { Attributes = new string[] { "contactid", "parentcustomerid", "firstname", "middlename", "lastname", "suffix", "emailaddress1", "emailaddress2", "emailaddress3", "statecode", "caad_duplicateid" } };
ConditionExpression condition = new ConditionExpression { AttributeName = "statecode", Operator = ConditionOperator.Equal, Values = new string[] { "Active" } };
FilterExpression filter = new FilterExpression { FilterOperator = LogicalOperator.And, Conditions = new ConditionExpression[] { condition } };
QueryExpression contactQuery = new QueryExpression { EntityName = EntityName.contact.ToString(), ColumnSet = cols, Criteria = filter };
BusinessEntityCollection contacts = CRMConnectionHelper.crmService.RetrieveMultiple(contactQuery); //Exception: server cannot process request
int qty = contacts.BusinessEntities.Length;
Console.WriteLine(String.Format("Total number of contacts {0}", qty));
for (int i = 0; i < qty; i++)
{
try
{
contact c = (contact)contacts.BusinessEntities[i];
account ac = new account();
if (c.parentcustomerid != null)
{
ac = (account)(from a in accs where a.accountid.Value == c.parentcustomerid.Value select a).FirstOrDefault();
cnts.Add(new CrmContact(ac, c));
}
else
{
cnts.Add(new CrmContact(null, c));
}
}
catch (Exception ex)
{
Console.WriteLine(String.Format("GetActiveContacts: Error for i={0} : {1}", i, ex.Message));
Console.Read();
}
}
}
catch (Exception ex)
{
Console.WriteLine(String.Format("Exception occured trying to get active contacts: {0}", ex));
Console.Read();
}
}
}
}
何か洞察があれば教えてください。ありがとうございました。