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  • ReSharper show warning with SqlDataReader

    - by Belousov Pavel
    When I write something like this: using (var connection = new SqlConnection("ConnectionString")) { using(var cmd= new SqlCommand("Command")) { using (var reader = cmd.ExecuteReader()) { while (reader.Read()) { } } } } ReSharper shows warning on reader.Read(), and tells that reader can be null. But in what cases can it be null? As I know if command returns nothing reader is not null, it only have nothing.

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  • How do I read live camera data on the iPhone (like Microsoft Tag Reader)?

    - by Bill
    While the user is still in UIImagePickerController, I'd like to be able to get a UIImage representation of the image in the camera, make some changes to the image, and then display the altered image instead of the image coming directly from the camera. How can I do this? I tried setting a timer and calling takePicture, but calling it seemed to have no effect. The documentation says: Calling this method while an image is being captured has no effect. You must wait until the associated delegate object receives an imagePickerController:didFinishPickingMediaWithInfo: message before you can capture another picture. So how can I do this? I know that it's possible, since apps like Tag Reader are able to detect when something specific rolls in front of the camera. Thanks!

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  • What's the most DRY-appropriate way to execute an SQL command?

    - by Sean U
    I'm looking to figure out the best way to execute a database query using the least amount of boilerplate code. The method suggested in the SqlCommand documentation: private static void ReadOrderData(string connectionString) { string queryString = "SELECT OrderID, CustomerID FROM dbo.Orders;"; using (SqlConnection connection = new SqlConnection(connectionString)) { SqlCommand command = new SqlCommand(queryString, connection); connection.Open(); SqlDataReader reader = command.ExecuteReader(); try { while (reader.Read()) { Console.WriteLine(String.Format("{0}, {1}", reader[0], reader[1])); } } finally { reader.Close(); } } } mostly consists of code that would have to be repeated in every method that interacts with the database. I'm already in the habit of factoring out the establishment of a connection, which would yield code more like the following. (I'm also modifying it so that it returns data, in order to make the example a bit less trivial.) private SQLConnection CreateConnection() { var connection = new SqlConnection(_connectionString); connection.Open(); return connection; } private List<int> ReadOrderData() { using(var connection = CreateConnection()) using(var command = connection.CreateCommand()) { command.CommandText = "SELECT OrderID FROM dbo.Orders;"; using(var reader = command.ExecuteReader()) { var results = new List<int>(); while(reader.Read()) results.Add(reader.GetInt32(0)); return results; } } } That's an improvement, but there's still enough boilerplate to nag at me. Can this be reduced further? In particular, I'd like to do something about the first two lines of the procedure. I don't feel like the method should be in charge of creating the SqlCommand. It's a tiny piece of repetition as it is in the example, but it seems to grow if transactions are being managed manually or timeouts are being altered or anything like that.

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  • Assigning values to the lable through database depending on listbox values

    - by SurajVitekar
    I want to assign the values of five labels from database regarding to values selected in listbox. The db query returns single column with multiple records. Please help. I'm working with C# 2010 and MS SQL. My current code is: private void listBox1_SelectedIndexChanged(object sender, EventArgs e) { try { String c1, c2; c1 = "NULL"; MessageBox.Show("LB index :"+listBox1.SelectedIndex.ToString()); //p = listBox1.SelectedItem.ToString(); SqlConnection con = new SqlConnection(); con.ConnectionString = "Data Source=localhost;Initial Catalog=eVoting;Integrated Security=True;Pooling=False"; con.Open(); MessageBox.Show("List bOx sect :"+listBox1.SelectedValue.ToString()); SqlCommand cmd = new SqlCommand("select Firstname from candidates where position ='" + listBox1.SelectedValue.ToString() + "'", con); int index = 0; SqlDataReader reader = cmd.ExecuteReader(); while(reader.Read()) { if (index == 0) { c1 = reader[index].ToString(); radioButton1.Text = c1; } if (index == 1) { c1 = reader[index].ToString(); radioButton2.Text = c1; } if (index == 2) { c1 = reader[index].ToString(); radioButton3.Text = c1; } if (index == 3) { c1 = reader[index].ToString(); radioButton4.Text = c1; } if (index == 4) { c1 = reader[index].ToString(); radioButton4.Text = c1; } if (index == 5) { c1 = reader[index].ToString(); radioButton5.Text = c1; } MessageBox.Show("c1 :" + c1); index++; } } catch (Exception E) { } }

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  • mysql data read returning 0 rows from class

    - by Neo
    I am implementing a database manager class within my app, mainly because there are 3 databases to connect to one being a local one. However the return function isn't working, I know the query brings back rows but when it is returned by the class it has 0. What am I missing? public MySqlDataReader localfetchrows(string query, List<MySqlParameter> dbparams = null) { using (var conn = connectLocal()) { Console.WriteLine("Connecting local : " + conn.ServerVersion); MySqlCommand sql = conn.CreateCommand(); sql.CommandText = query; if (dbparams != null) { if (dbparams.Count > 0) { sql.Parameters.AddRange(dbparams.ToArray()); } } MySqlDataReader reader = sql.ExecuteReader(); Console.WriteLine("Reading data : " + reader.HasRows + reader.FieldCount); return reader; /* using (MySqlCommand sql = conn.CreateCommand()) { sql.CommandText = query; if (dbparams != null) { if (dbparams.Count > 0) { sql.Parameters.AddRange(dbparams.ToArray()); } } MySqlDataReader reader = sql.ExecuteReader(); Console.WriteLine("Reading data : " + reader.HasRows + reader.FieldCount); sql.Parameters.Clear(); return reader; }*/ } } And the code to get the results query = @"SELECT jobtypeid, title FROM jobtypes WHERE active = 'Y' ORDER BY title ASC"; //parentfrm.jobtypes = db.localfetchrows(query); var rows = db.localfetchrows(query); Console.WriteLine("Reading data : " + rows.HasRows + rows.FieldCount); while (rows.Read()){ } These scripts return the following : Connecting local : 5.5.16 Reading data : True2 Reading data : False0

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  • How to convert PowerPoint presentations into a Kindle/E-reader friendly form?

    - by Shiki
    I have a lot of documents in .ppt and .pptx (blame the co-workers). I would like to read them on way home or elsewhere... when I have a little time to catch up with things. One thing I could do with the documents is cutting them together into one file. But saving that one even if a smaller version of PDF (according to Office 2010) results in a huge file. And PDF is hardly readable on a Kindle. I would need something .epub free, easy-on-the-device way. Is there such a thing? (Manually I could copy all the images down into native text and whatnot and create new presentations, save those, convert them. But that would just take a lot of time.)

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  • How can I read PDFs with e-reader on a Lenovo tablet?

    - by Jack M
    This is my first time using a tablet and I'm totally lost - this must be what computers look like to old people. This is a Lenovo Thinkpad tablet. I don't see a specific model number on it (it was passed down to me second hand). What I'd like to do is read a PDF. I'm fairly certain I successfully transferred the PDF onto the tablet via an SD card, and I noticed this thing has an app called "eReader" on it, so I started that up. All I see are empty bookshelves, and no obvious buttons or settings anywhere. I saw in multiple places that you have to, as one site puts it: ...copy and paste the relevant files into the eBooks folder and they will appear on the eReader shelf for your consumption... But I have no idea how to: Access the file system. Locate the eBooks folder. Copy and paste files. Will I need a file explorer app? If so, how can I install that given that my only method of getting data onto this tablet is an SD card (no wireless internet).

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  • Will any USB DVD reader work with Apple Mac's?

    - by Kev
    Following on from this question: Can Apple Macintosh computers boot from a USB volume? Can I use any USB 2.0 DVD drive to boot a Mac from? I had a look around my local PC World today and only the more expensive drives explicitly state on the packaging that they were Mac compatible. Is this just because these products have been through Apple's hardware approval/testing programme, or do Mac's have some special requirement?

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  • Back button of Adobe PDF Reader after clicking a hyperlink whose target is on the same document

    - by artknish
    PDF documents have hyperlinks to the contents on the same document (analogous to "#section" hrefs for an HTML document). Where's the back button to go back to the page I was on (where I clicked the hyperlink). Let's say I'm on the index of a PDF tutorial, page 4, and I click on Chapter 2's hyperlink in the index that takes me to page 38. Now, if I want to go back to page 4 again, which button or shortcut should I use?

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  • Back button of Adobe PDF Reader after clicking a hyperlink whose target is on the same document

    - by artknish
    PDF documents have hyperlinks to the contents on the same document (analogous to "#section" hrefs for an HTML document). Where's the back button to go back to the page I was on (where I clicked the hyperlink). Let's say I'm on the index of a PDF tutorial, page 4, and I click on Chapter 2's hyperlink in the index that takes me to page 38. Now, if I want to go back to page 4 again, which button or shortcut should I use?

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  • How to search a PDF in Acrobat Reader AND jump to a certain page via parameter?

    - by agez
    Hi, we are using lucene within a web application to search in a great number of PDF documents. The workflow is like this: A user enters a search term A list of search results is presented to the user. Each search result represents one PDF document and shows the user on which page the search term was found. Each of these pages is represented as a hyperlink. If the user now clicks on such a hyperlink, he directly jumps to that page. But now the user has the problem that the search term isn't highlighted on the page. Therefore the user has to look on his own to find the search term on the page. What we wanted is a way to highlight the search term on the specific page in the PDF. The open parameters for Acrobat Reader allow for either searching a PDF document (with hit highlighting) OR jumping to a specific page. But the combination of both parameters - which we would need - doesn't work. Does anyone have an idea how jumping to a page and highlighting a search term in a pdf document could work? I had a look at the Acrobat SDK but don't see how we can use it (it's terribly documented). Cheers, Helmut

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  • Why slim reader/writer exclusive lock outperformance the shared one?

    - by Jichao
    I have tested the performance of slim reader/writer lock under windows 7 using the codefrom Windows Via C/C++. The result surprised me that the exclusive lock out performance the shared one. Here are the code and the result. unsigned int __stdcall slim_reader_writer_exclusive(void *arg) { //SRWLOCK srwLock; //InitializeSRWLock(&srwLock); for (int i = 0; i < 1000000; ++i) { AcquireSRWLockExclusive(&srwLock); g_value = 0; ReleaseSRWLockExclusive(&srwLock); } _endthreadex(0); return 0; } unsigned int __stdcall slim_reader_writer_shared(void *arg) { int b; for (int i = 0; i < 1000000; ++i) { AcquireSRWLockShared(&srwLock); //b = g_value; g_value = 0; ReleaseSRWLockShared(&srwLock); } _endthreadex(0); return 0; } g_value is a global int volatile variable. Could you kindly explain why this could happen?

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  • ASP.NET SqlDataReader throwing error: Invalid attempt to call Read when reader is closed.

    - by Bugget
    This one has me stumped. Here are the relative bits of code: public AgencyDetails(Guid AgencyId) { try { evgStoredProcedure Procedure = new evgStoredProcedure(); Hashtable commandParameters = new Hashtable(); commandParameters.Add("@AgencyId", AgencyId); SqlDataReader AppReader = Procedure.ExecuteReaderProcedure("evg_getAgencyDetails", commandParameters); commandParameters.Clear(); //The following line is where the error is thrown. Errormessage: Invalid attempt to call Read when reader is closed. while (AppReader.Read()) { AgencyName = AppReader.GetOrdinal("AgencyName").ToString(); AgencyAddress = AppReader.GetOrdinal("AgencyAddress").ToString(); AgencyCity = AppReader.GetOrdinal("AgencyCity").ToString(); AgencyState = AppReader.GetOrdinal("AgencyState").ToString(); AgencyZip = AppReader.GetOrdinal("AgencyZip").ToString(); AgencyPhone = AppReader.GetOrdinal("AgencyPhone").ToString(); AgencyFax = AppReader.GetOrdinal("AgencyFax").ToString(); } AppReader.Close(); AppReader.Dispose(); } catch (Exception ex) { throw new Exception("AgencyDetails Constructor: " + ex.Message.ToString()); } } And the implementation of ExecuteReaderProcedure: public SqlDataReader ExecuteReaderProcedure(string ProcedureName, Hashtable Parameters) { SqlDataReader returnReader; using (SqlConnection conn = new SqlConnection(connectionString)) { try { SqlCommand cmd = new SqlCommand(ProcedureName, conn); SqlParameter param = new SqlParameter(); cmd.CommandType = System.Data.CommandType.StoredProcedure; foreach (DictionaryEntry keyValue in Parameters) { cmd.Parameters.AddWithValue(keyValue.Key.ToString(), keyValue.Value); } conn.Open(); returnReader = cmd.ExecuteReader(CommandBehavior.CloseConnection); } catch (SqlException e) { throw new Exception(e.Message.ToString()); } } return returnReader; } The connection string is working as other stored procedures in the same class run fine. The only problem seems to be when returning SqlDataReaders from this method! They throw the error message in the title. Any ideas are greatly appreciated! Thanks in advance!

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  • C# powershell output reader iterator getting modified when pipeline closed and disposed.

    - by scope-creep
    Hello, I'm calling a powershell script from C#. The script is pretty small and is "gps;$host.SetShouldExit(9)", which list process, and then send back an exit code to be captured by the PSHost object. The problem I have is when the pipeline has been stopped and disposed, the output reader PSHost collection still seems to be written to, and is filling up. So when I try and copy it to my own output object, it craps out with a OutOfMemoryException when I try to iterate over it. Sometimes it will except with a Collection was modified message. Here is the code. private void ProcessAndExecuteBlock(ScriptBlock Block) { Collection<PSObject> PSCollection = new Collection<PSObject>(); Collection<Object> PSErrorCollection = new Collection<Object>(); Boolean Error = false; int ExitCode=0; //Send for exection. ExecuteScript(Block.Script); // Process the waithandles. while (PExecutor.PLine.PipelineStateInfo.State == PipelineState.Running) { // Wait for either error or data waithandle. switch (WaitHandle.WaitAny(PExecutor.Hand)) { // Data case 0: Collection<PSObject> data = PExecutor.PLine.Output.NonBlockingRead(); if (data.Count > 0) { for (int cnt = 0; cnt <= (data.Count-1); cnt++) { PSCollection.Add(data[cnt]); } } // Check to see if the pipeline has been closed. if (PExecutor.PLine.Output.EndOfPipeline) { // Bring back the exit code. ExitCode = RHost.ExitCode; } break; case 1: Collection<object> Errordata = PExecutor.PLine.Error.NonBlockingRead(); if (Errordata.Count > 0) { Error = true; for (int count = 0; count <= (Errordata.Count - 1); count++) { PSErrorCollection.Add(Errordata[count]); } } break; } } PExecutor.Stop(); // Create the Execution Return block ExecutionResults ER = new ExecutionResults(Block.RuleGuid,Block.SubRuleGuid, Block.MessageIdentfier); ER.ExitCode = ExitCode; // Add in the data results. lock (ReadSync) { if (PSCollection.Count > 0) { ER.DataAdd(PSCollection); } } // Add in the error data if any. if (Error) { if (PSErrorCollection.Count > 0) { ER.ErrorAdd(PSErrorCollection); } else { ER.InError = true; } } // We have finished, so enque the block back. EnQueueOutput(ER); } and this is the PipelineExecutor class which setups the pipeline for execution. public class PipelineExecutor { private Pipeline pipeline; private WaitHandle[] Handles; public Pipeline PLine { get { return pipeline; } } public WaitHandle[] Hand { get { return Handles; } } public PipelineExecutor(Runspace runSpace, string command) { pipeline = runSpace.CreatePipeline(command); Handles = new WaitHandle[2]; Handles[0] = pipeline.Output.WaitHandle; Handles[1] = pipeline.Error.WaitHandle; } public void Start() { if (pipeline.PipelineStateInfo.State == PipelineState.NotStarted) { pipeline.Input.Close(); pipeline.InvokeAsync(); } } public void Stop() { pipeline.StopAsync(); } } An this is the DataAdd method, where the exception arises. public void DataAdd(Collection<PSObject> Data) { foreach (PSObject Ps in Data) { Data.Add(Ps); } } I put a for loop around the Data.Add, and the Collection filled up with 600k+ so feels like the gps command is still running, but why. Any ideas. Thanks in advance.

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  • "this device cannot start error code 10" ?

    - by Neo
    I am trying to install GPS driver for gmm-u1lp.I think which is just a virtual com port driver. It just contains following INF file: [Version] Signature="$Windows NT$" Class=Ports ClassGuid={4D36E978-E325-11CE-BFC1-08002BE10318} Provider=%MTK% ;LayoutFile=layout.inf DriverVer=06/12/2007,1.0.0.1 [Manufacturer] %MTK%=MTK [MTK] %MTK3329%=Reader,USB\Vid_0e8d&Pid_3329 [Reader_Install.NTx86] ;Windows2000 [DestinationDirs] DefaultDestDir=12 Reader.NT.Copy=12 [Reader.NT] Include=mdmcpq.inf CopyFiles=FakeModemCopyFileSection AddReg=Reader.NT.AddReg [Reader.NT.AddReg] HKR,,DevLoader,,*ntkern HKR,,NTMPDriver,,usbser.sys HKR,,EnumPropPages32,,"MsPorts.dll,SerialPortPropPageProvider" [Reader.NT.Services] AddService = usbser, 0x00000002, Service_Inst [Service_Inst] DisplayName = %Serial.SvcDesc% ServiceType = 1 ; SERVICE_KERNEL_DRIVER StartType = 3 ; SERVICE_DEMAND_START ErrorControl = 1 ; SERVICE_ERROR_NORMAL ServiceBinary = %12%\usbser.sys LoadOrderGroup = Base [Strings] MTK = "Media Tek Inc." MTK3329 = "GPS USB Serial Interface Driver" Serial.SvcDesc = "GPS USB Serial Interface Driver" After installing this Inf,device details shows:"device cannot start error code 10". What is the exact problem? Do I need to test this after connecting the Device?

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  • How to tell if a datareader is open on a connection and close it

    - by Earlz
    Hi, I'm setting up a little thing for connection pooling and on of the more common bugs that we have occur(its always an easy fix, but we just can't remember reader.Close()!) it is when we have a connection that is used by a lot of classes/methods and one method opens a data reader and forgets to close it. This isn't really bad cause a lot of times all you have to do is go into the debugger and go up one level and see the function before it was and check if it had an unclosed data reader. Now, here is the bigger problem. In this connection pool, if a datareader is open, then it's not known until a thread gets a connection and tries to use it and the thing that originally opened the data reader may no longer even be alive. So quite simply, how can you detect if a data reader is open on a connection and is there a way to close the reader without closing the connection?

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  • c# reading integer fields from database, returning empty string when reading integer type field

    - by arnoldino
    what is wrong with this code? field="id"; table="MInvMonth"; condition="machine_id=37"; public static String getConditionedField(String field, String table, String condition) try { if (cmd == null) getConnection(); cmd.CommandText = "Select " + field + " from " + table + " where " + condition; SQLiteDataReader reader = cmd.ExecuteReader(); if (reader.HasRows==true) { reader.Read(); string s = reader[0].ToString(); // return first element reader.Close(); return s; } reader.Close(); return null; } catch (Exception e) { MessageBox.Show("Caught exception: " + e.Message+"|"+cmd.CommandText); return null; } I checked the sql statement, it turns the right value. why can't I read it? the returnvalue is "".

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  • How to initialize F# list when size is unknown, using while..do loop

    - by James Black
    I have a function that will parse the results of a DataReader, and I don't know how many items are returned, so I want to use a while..do loop to iterate over the reader, and the outcome should be a list of a certain type. (fun(reader) -> [ while reader.Read() do new CityType(Id=(reader.GetInt32 0), Name=(reader.GetString 1), StateName=(reader.GetString 2)) ]) This is what I tried, but the warning I get is: This expression should have type 'unit', but has type 'CityType'. Use 'ignore' to discard the result of the expression, or 'let' to bind the result to a name. So what is the best way to iterate over a DataReader and create a list?

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