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You don't have to compile it on a 64-bit machine. You DO have to go into the Project Properties, Build tab, and make sure that "Platform target" is set to "x64".
After that, you have to make sure your connection string, as deployed onto the server, is accurate.
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I am new in EF. I mostly use ADO.Net to interact with DB. So learning EF code first.
Just see a below code. Post and blog class which has one-to-many relation I guess...........am I right?
public class Blog
{
public int BlogId { get; set; }
public string Name { get; set; }
public virtual List<Post> Posts { get; set; }
}
public class Post
{
public int PostId { get; set; }
public string Title { get; set; }
public string Content { get; set; }
public int BlogId { get; set; }
public virtual Blog Blog { get; set; }
}
why blog class has one virtual property list type of Post?
And same way why post class has one virtual property type of Blog?
if we remove the virtual keyword only then what will happen?
how virtual keyword create relation?
why virtual keyword has been used in two class?
Please answer my all questions point wise in details.
tbhattacharjee
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Did you even bother reading the answers the last time you posted about this[^]?
This space for rent
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Hi everyone,
I would like your opinion on the following. I have an abstract base class with a property:
public abstract class BaseClass
{
public abstract double SomeProperty { get; set; }
}
I have several derived classes based on it. Some of these derived classes have a fixed value for the property, and some do not. How would you implement the derived classes with the fixed value for SomeProperty? Maybe something like this:
public class DerivedClass : BaseClass
{
private double _fixedValue;
public override double SomeProperty
{
get { return _fixedValue; }
set { _fixedValue = 1d; }
}
}
The problem with the above implementation is that I can access the property from the outside and the code makes me think I can modify the value, but it will always give me the same result. This is not what I want, obviously.
Maybe I need to rethink how to set up the base class? If so, do you have any suggestions?
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You don't actually have to implement anything inside the setter so it's perfectly possible to do this:
public class DerivedClass : BaseClass
{
public override double SomeProperty
{
get { return 1d; }
set { }
}
}
This space for rent
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As Pete says, you don't have to put anything in the setter.
But I must admit, I don't like that, as you can still write:
DerivedClass dc = new DerivedClass();
dc.SomeProperty = 23.0;
And it will appear to work - there is no compile or runtime error here which is potentially confusing:
public class DerivedClass2 : BaseClass
{
public override double SomeProperty { get; set; }
}
Allows:
BaseClass bc = new DerivedClass();
bc.SomeProperty = 23.0;
bc = new DerivedClass2();
bc.SomeProperty = 23.0;
Which doesn't do the same thing in both cases.
You could throw an exception in the "unwanted" setter:
public class DerivedClass : BaseClass
{
public override double SomeProperty
{
get { return 1d; }
set { throw new ApplicationException("Cannot set SomeProperty of DerivedClass - it is read only"); }
}
}
But that just moves the problem to runtime and I don't like that either.
It might be better to make the Setter protected :
public abstract class BaseClass
{
public abstract double SomeProperty { get; protected set; }
}
Because at least then you are restricting the confusion to classes that are directly involved, instead of letting the rest of the world get confused as well.
Bad command or file name. Bad, bad command! Sit! Stay! Staaaay...
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I learn something: I happy. You good.
«There is a spectrum, from "clearly desirable behaviour," to "possibly dodgy behavior that still makes some sense," to "clearly undesirable behavior." We try to make the latter into warnings or, better, errors. But stuff that is in the middle category you don’t want to restrict unless there is a clear way to work around it.» Eric Lippert, May 14, 2008
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"If you learn something new every day, you can teach something new every day." --- Martha Stewart
My wife learns something new from me everyday. She thinks it's important to learn from her mistakes.
Bad command or file name. Bad, bad command! Sit! Stay! Staaaay...
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Hello,
I have problem with insert timestamp to PDF.
On line Array.Copy(pk, 0, outc, 0, pk.Length); is error because outc.Length = 4096, but pk.Length = 7541. Metod DejCasoveRazitko work correctly.
P.S. Sorry, my English is bad
private const String ID_TIME_STAMP_TOKEN = "1.2.840.113549.1.9.16.2.14";
public void PodepisPdfCer(string SouborPDF, string OtiskCertifikatu)
{
var store = new System.Security.Cryptography.X509Certificates.X509Store(System.Security.Cryptography.X509Certificates.StoreName.My, System.Security.Cryptography.X509Certificates.StoreLocation.CurrentUser);
store.Open(System.Security.Cryptography.X509Certificates.OpenFlags.ReadOnly);
string thumbprint = OtiskCertifikatu.Replace(" ", "").ToUpperInvariant();
if (thumbprint[0] == 8206)
{
thumbprint = thumbprint.Substring(1);
}
var certs = store.Certificates.Find(System.Security.Cryptography.X509Certificates.X509FindType.FindByThumbprint, thumbprint, true);
store.Close();
if (certs.Count == 0)
{
MessageBox.Show("Nelze najít určený certifikát v Current user certificate store!", "Sign PDF", MessageBoxButtons.OK, MessageBoxIcon.Warning);
return;
}
byte[] pdfData = File.ReadAllBytes(SouborPDF);
using (MemoryStream stream = new MemoryStream())
{
var reader = new PdfReader(pdfData);
var stp = PdfStamper.CreateSignature(reader, stream, '\0');
var sap = stp.SignatureAppearance;
stp.SetEncryption(null,
Guid.NewGuid().ToByteArray(),
PdfWriter.ALLOW_PRINTING | PdfWriter.ALLOW_COPY | PdfWriter.ALLOW_SCREENREADERS,
PdfWriter.ENCRYPTION_AES_256);
var cp = new Org.BouncyCastle.X509.X509CertificateParser();
var certChain = new Org.BouncyCastle.X509.X509Certificate[] { cp.ReadCertificate(certs[0].RawData) };
sap.SetCrypto(null, certChain, null, PdfSignatureAppearance.WINCER_SIGNED);
BaseFont helvetica = BaseFont.CreateFont(BaseFont.HELVETICA, BaseFont.CP1250, BaseFont.EMBEDDED);
iTextSharp.text.Font font = new iTextSharp.text.Font(helvetica, 12, iTextSharp.text.Font.NORMAL);
sap.Layer2Font = font;
var dic = new PdfSignature(PdfName.ADOBE_PPKMS, PdfName.ADBE_PKCS7_SHA1);
dic.Date = new PdfDate(sap.SignDate);
dic.Name = certs[0].Subject;
if (sap.Reason != null)
{
dic.Reason = sap.Reason;
}
if (sap.Location != null)
{
dic.Location = sap.Location;
}
sap.CryptoDictionary = dic;
int csize = 4096;
var reservedSpace = new Dictionary<PdfName, int>();
reservedSpace[PdfName.CONTENTS] = csize * 2 + 2;
sap.PreClose(reservedSpace);
System.Security.Cryptography.HashAlgorithm sha = new System.Security.Cryptography.SHA256CryptoServiceProvider();
var sapStream = sap.GetRangeStream();
int read = 0;
byte[] buff = new byte[8192];
while ((read = sapStream.Read(buff, 0, 8192)) > 0)
{
sha.TransformBlock(buff, 0, read, buff, 0);
}
sha.TransformFinalBlock(buff, 0, 0);
System.Security.Cryptography.Pkcs.ContentInfo contentInfo = new System.Security.Cryptography.Pkcs.ContentInfo(sha.Hash);
System.Security.Cryptography.Pkcs.SignedCms signedCms = new System.Security.Cryptography.Pkcs.SignedCms(contentInfo, false);
System.Security.Cryptography.Pkcs.CmsSigner cmsSigner = new System.Security.Cryptography.Pkcs.CmsSigner(certs[0]);
cmsSigner.IncludeOption = System.Security.Cryptography.X509Certificates.X509IncludeOption.ExcludeRoot;
if (!String.IsNullOrEmpty(textBox_ServerCasovehoRazitka.Text.Trim()))
{
try
{
System.Security.Cryptography.AsnEncodedData timeData = new System.Security.Cryptography.Pkcs.Pkcs9AttributeObject(ID_TIME_STAMP_TOKEN,
DejCasoveRazitko(stream.GetBuffer(), textBox_ServerCasovehoRazitka.Text)
);
cmsSigner.UnsignedAttributes.Add(timeData);
}
catch (Exception e)
{
MessageBox.Show("Chyba TSA!\n" + e.Message);
}
}
signedCms.ComputeSignature(cmsSigner, false);
byte[] pk = signedCms.Encode();
byte[] outc = new byte[csize];
Array.Copy(pk, 0, outc, 0, pk.Length);
PdfDictionary certificateDictionary = new PdfDictionary();
sap.Close(certificateDictionary);
stp.Close();
reader.Close();
byte[] signedData = stream.GetBuffer();
File.WriteAllBytes(SouborPDF, signedData);
}
}
static protected byte[] DejCasoveRazitko(byte[] PDF, string ServerTSA)
{
System.Security.Cryptography.SHA256Managed hashString = new System.Security.Cryptography.SHA256Managed();
string hex = "";
var hashValue = hashString.ComputeHash(PDF);
foreach (byte x in hashValue)
{
hex += String.Format("{0:x2}", x);
}
NotservisTSA.GetTimeStampRequest Request = new NotservisTSA.GetTimeStampRequest(new NotservisTSA.GetTimeStampRequestBody(hex, 0));
NotservisTSA.Print2PDF_WebServiceSoap Soap = new NotservisTSA.Print2PDF_WebServiceSoapClient();
((NotservisTSA.Print2PDF_WebServiceSoapClient)Soap).Endpoint.Address = new System.ServiceModel.EndpointAddress(new Uri(ServerTSA + "/Default.asmx"));
PodepsaniPDF.NotservisTSA.GetTimeStampResponse Response = Soap.GetTimeStamp(Request);
byte[] responseBytes = Encoding.ASCII.GetBytes(Response.Body.GetTimeStampResult);
if(!String.IsNullOrEmpty(Response.Body.Error))
MessageBox.Show(Response.Body.Error, "Chyba", MessageBoxButtons.OK, MessageBoxIcon.Error);
string base64String = Encoding.UTF8.GetString(responseBytes, 0, responseBytes.Length);
return Convert.FromBase64String(base64String);
}
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Hi Team,
Could someone suggest ideal way to submit 100s of rows from UI to db ?
i think better approach would be to Prepare XML and send it to DB.
Any other ideas are welcome.
Thanks,
Giri
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Depends on the database-server.
In the case of SQLite, you'd be better of doing 100 inserts wrapped in a transaction.
Bastard Programmer from Hell
If you can't read my code, try converting it here[^]
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Hello all. I have a background worker that executes a query against an SQL Server database. The user clicks a button and the query runs, then the results of the query go into a datagrid. The users are requesting a Cancel button for the query because the queries can take a very long time to run. So when the user clicks the Run Query button, a small form with a Cancel Button opens. If the user clicks the button, DialogueResult.Cancel is returned and I execute CancelAsync().
Meanwhile, in my DoWork thread, I am preparing to run the query. When I run the query, I execute
adapter3.Fill(GlobalData.g_queryData);
So, there is no loop. Most of the forums I have seen tell you to check Backgroundworker.CancellationPending. The problem is that I am not running in a loop.
So, can someone suggest maybe another approach to canceling a query that is currently running?
Thanks,
David
using (SqlConnection connection = new SqlConnection(GlobalStr.sqlConnStringMetadata))
{
try
{
connection.Open();
SqlTransaction Transaction = connection.BeginTransaction(IsolationLevel.ReadUncommitted);
using (SqlCommand testQuery = new SqlCommand(GlobalStr.previewQueryString, connection))
{
testQuery.CommandTimeout = m_QueryTimeout;
testQuery.Transaction = Transaction;
using (SqlDataAdapter adapter3 = new SqlDataAdapter(testQuery))
{
adapter3.Fill(GlobalData.g_queryData);
DataSetViewer dsv = new DataSetViewer();
dsv.SetSource(GlobalData.g_queryData);
string strClassification = string.Format("{0} {1}", GlobalStr.g_classification, GlobalStr.g_releaseability);
dsv.setClassification(strClassification);
Cursor.Current = Cursors.Default;
dsv.ShowDialog();
}
}
connection.Close();
}
catch (Exception ex)
{
MessageBox.Show("The query test failed: " + ex.Message);
return;
}
}
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I have accomplished a similar task in the past using a variation of this code:
public sealed class ExtendedBackgroundWorker : BackgroundWorker
{
private Thread thread;
public void Stop()
{
thread?.Abort();
thread = null;
}
protected override void OnDoWork(DoWorkEventArgs eventArgs)
{
thread = Thread.CurrentThread;
try
{
base.OnDoWork(eventArgs);
}
catch (ThreadAbortException threadAbort)
{
Debug.WriteLine("ExtendedBackgroundWorker has been aborted");
Thread.ResetAbort();
eventArgs.Cancel = true;
}
}
} With this, you're going to Abort the Thread. Now, an Abort is normally a bad method to call (there are various resources you can look up about why it's not recommended), but we're going to handle it in a controlled manner. When the thread is aborted, a ThreadAbortException is raised so, in our OnDoWork handler, we want to Cancel the DoWorkEventArgs and reset the Abort so that it doesn't destabilise our system. Now, you have a background worker that can be killed from the calling code. By the way, I call the method Stop rather than Abort because while this code is carefully written to prevent Abort issues, I don't want people to get into the habit of calling Abort wherever they see thread codes. By hiding the implementation, I'm hiding the idea that Abort should be called.
This space for rent
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Thank you Peter. I actually worked on this over my long weekend. Sorry for not getting back to you sooner.
I got it working by partly using your suggestion to abort the thread. This works because the only types of queries that will be run here are SELECT queries. So no records are actually being modified. So, no need to worry about rolling back transactions.
I am no longer using a background worker. I am just creating my own thread. I want to show my code below.
Class Level Code:
CloseCancelForm();
Cancel Form
public partial class FormCancelQuery : Form
{
DialogResult result = DialogResult.OK;
public FormCancelQuery()
{
InitializeComponent();
}
private void btnCancel_Click(object sender, EventArgs e)
{
result = DialogResult.Cancel;
this.Close();
}
}
Main UI Form
private void qbTestQueryBtn_Click(object sender, EventArgs e)
{
frmCancel = new FormCancelQuery();
RunQueryThread = new Thread(new ThreadStart(RunQuery));
RunQueryThread.Start();
DialogResult dr = frmCancel.ShowDialog(this);
if (dr == DialogResult.Cancel)
{
frmCancel.DialogResult = DialogResult.OK;
RunQueryThread.Abort();
}
}
private void RunQuery()
{
if (ValidQuery())
{
string queryTestString = GlobalStr.previewQueryString;
string fillFlag = "'mandafillflag'";
if (queryTestString.ToLower().Contains(fillFlag))
{
MessageBox.Show("This query requires completing the fields. Click OK to begin procedure.");
QueryFiller qf = new QueryFiller();
queryTestString = qf.FillQuery(queryTestString.ToLower(), fillFlag);
}
GlobalStr.previewQueryString = queryTestString;
selectTB.Invoke(new MethodInvoker(delegate { selectTB.Text = GlobalStr.previewQueryString; }));
whereTB.Invoke(new MethodInvoker(delegate { whereTB.Clear(); }));
fromTB.Invoke(new MethodInvoker(delegate { fromTB.Clear(); }));
orderTB.Invoke(new MethodInvoker(delegate { orderTB.Clear(); }));
try
{
examineQueryInputString(GlobalStr.previewQueryString, "", GlobalBool.g_CmplxWhereClauseChecked);
}
catch (System.Exception ex)
{
CloseCancelForm();
MessageBox.Show(ex.Message);
return;
}
try
{
GlobalData.g_queryData.Rows.Clear();
GlobalData.g_queryData.Columns.Clear();
}
catch (Exception ex)
{
GlobalData.g_queryData = new DataTable();
}
Cursor.Current = Cursors.WaitCursor;
using (SqlConnection connection = new SqlConnection(GlobalStr.sqlConnStringMetadata))
{
try
{
connection.Open();
SqlTransaction Transaction = connection.BeginTransaction(IsolationLevel.ReadUncommitted);
using (SqlCommand testQuery = new SqlCommand(GlobalStr.previewQueryString, connection))
{
testQuery.CommandTimeout = m_QueryTimeout;
testQuery.Transaction = Transaction;
using (SqlDataAdapter adapter3 = new SqlDataAdapter(testQuery))
{
adapter3.Fill(GlobalData.g_queryData);
DataSetViewer dsv = new DataSetViewer();
dsv.SetSource(GlobalData.g_queryData);
string strClassification = string.Format("{0} {1}", GlobalStr.g_classification, GlobalStr.g_releaseability);
dsv.setClassification(strClassification);
Cursor.Current = Cursors.Default;
CloseCancelForm();
dsv.ShowDialog();
}
}
connection.Close();
}
catch (Exception ex)
{
if (ex.Message != "Thread was being aborted.")
{
CloseCancelForm();
MessageBox.Show("The query test failed: " + ex.Message);
}
return;
}
}
}
else
{
CloseCancelForm();
MessageBox.Show("SQL test failed.");
}
}
private void CloseCancelForm()
{
try
{
if (frmCancel.InvokeRequired)
{
frmCancel.Invoke(new MethodInvoker(delegate { frmCancel.DialogResult = DialogResult.OK; }));
frmCancel.Invoke(new MethodInvoker(delegate { frmCancel.Close(); }));
}
else
{
frmCancel.DialogResult = DialogResult.OK;
frmCancel.Close();
}
}
catch(Exception ex)
{
string message = ex.Message;
return;
}
}
Hopefully this will help someone.
David
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Thanks for coming back and posting your update. Glad you got it working.
This space for rent
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Yes; the usual reaction is to figure out how to "cancel the query".
Perhaps one should first look at "tuning" the query.
The "query" is being confused with the "what it is that is submitting the query" (existentially speaking). The "query" is the "database server engine"; not some thread that submitted the query.
Is the query returning a scalar or a "set"?
If a set, is it required to be viewed and paged? Reported on?
Is virtualization an option for "paged" results.
Can the execution plan be estimated and presented before kicking off the query?
What is the nature of query? Would a data reader suffice? Can intermediate results be used to confirm kicking of further queries instead of resorting to a single "large" (poorly optimized) query (e.g. when "drilling" down).
etc....
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Hi Gerry,
These are user created queries, so there is no tuning the query.
Yes, I guess you are correct. The query is being run by the database server engine, so I guess there is no canceling the query. All I can really do is force my program to stop waiting for the query results. I guess since the query is running in a transaction, I could try rolling back the transaction.
The query returns a set.
The query is created by the user through a query designer that we wrote in C#. It only allows the user to execute SELECT queries against tables or Views in the database. It returns a dataset with the results displayed in a datagrid. The results can then be exported to a CSV or XLSX file.
Thanks or your input.
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The queries may be "user-created", but that does not mean they should have "free access" to the database.
I would give users "unlimited" query abilities; but with some "reasonableness" applied.
With an ERP system, it makes little sense to run queries on "all".
Based on the context (User; Department; Title; etc.), users may be required to provide a "year", "month", "department code", etc. via a query interface.
For "historical" data analysis, we would build data warehouses ("facts"; dimensions; "star" relationships) that were "optimized" for ad-hoc queries.
One simply does not unleash users on "unstructured" data without some planning (and expect performance).
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Hi Gerry. They do not have free unlimited access to everything. We use User Roles to control what they have access to. They cannot run Action Queries or DROP or CREATE queries. If the application needs to do that, then we use an Application Role with elevated permissions. We have covered our bases I think.
Thanks,
David
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Also, just to be safe, we have an algorithm that validates their query and looks for those action query keywords such as DROP, DELETE, INSERT, CREATE, UPDATE, etc. It will not allow anyone to run queries with those keywords. We also have the user pick the tables that they want to run their query against from a combo box. The algorithm that loads the combo box only lists certain tables.
David
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When I said "free access", I did not mean: DELETE; DROP; etc.
I meant that a person who works in "Accounts Receivable" (AR) typically only deals with "AR" data that is current for the month, and a few previous; and NOT to xx years of data for every department in the company.
That's why one has "performance problems": users (or anybody) running "dumb" queries.
And if you need to "cancel it", it cannot have been that important.
If it WAS important, one typically creates a "canned query"; with a few "optional parameters".
Anything else is chaos; and you get blamed for the performance issues.
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Ok Gerry, I apologize. I misunderstood you.
In our environment, our SQL Server is on a non-Internet connected machine. And the data is Analysis data. More and more data is added on a regular basis. We have many millions of rows of data in several databases. Our data analysts run queries. Sometimes they create a query incorrectly (or inefficient) . We have had cases where a user will start a query before they go home for the day, and then when they come in the next morning, it is still running.
Some of our queries consist of many views joined together and some of them use scalar functions and table valued functions which get used repeatedly. This can of course slow the query down significantly. Anyway, previously the only way to cancel a query was to End Task on the program, now the user can just click the cancel button. It works very well.
Thanks,
David
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No need for apologies...
Different experiences.
With ERP systems, I configured the query screens based on the "questions" users wanted to ask; that always involved some combination of: Company; Department; Cost Centre; Client #; Invoice #; Work order $; Year; Month; Day; etc.
Some required fields; some optional; default values off the accounting cycle. Write once (all variations of the same but limited to "codes" in their HR profile).
Every new table / "entity" is automatically secured based on "need to know".
No "bad" queries in the "operational" world; for the "informational" needs (different ASAP), there is the data warehouse. Two worlds.
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I want to make a tool for loging form of facebook.
In the past i was make facebook windows form application in xmpp client connection, that was working but now facebook setting change and i can not design a login form with xmpp.
I want to design a windows form application with user name and password text box for facebook, please help me.
How can i login to facebook server with windows form application
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