Comment stocker un fichier dans un serveur sql à partir de winforms C++

Question

MON QUESTION: comment stocker un fichier dans un serveur SQL à l'aide de C++ à partir d'une application de formulaire Windows?

MON PROBLÈME: Je lis les données binaires d'un fichier puis j'ouvre une connexion à SQL Server 2014. Lorsque j'envoie ma commande sql à la base de données avec les données binaires, je reçois un message d'erreur "Echec de conversion du paramètre valeur d'un octet à un octet []. ". Je vois beaucoup de gens utilisant cette méthode dans les applications C#. Comment est-ce que je l'adapte pour C++?

MON CODE:

void AddFileToDatabase() { 
    unsigned char* binaryData; // holds the files binary data 
    int sizeOfBinaryData = 0; // the size of binaryData in bytes 

    // Open the test file in binary mode and read the contents into 'binaryData' 
    std::ifstream inFile("a.txt", std::ios::in | std::ios::binary); // open the test file 'a.txt' 
    if(inFile.is_open()) { 
     inFile.seekg(0,std::ios::end); // move to the end of the file 
     sizeOfBinaryData = (int)inFile.tellg(); // get the file size 
     inFile.seekg(0,std::ios::beg); // move to the start of the file 

     binaryData = new unsigned char[sizeOfBinaryData]; // create space for the binary data 
     inFile.read((char*)binaryData,sizeOfBinaryData); // read in the binary data 
     inFile.close(); // close the file 
    } 

    // Connect to the database 
    System::Data::SqlClient::SqlConnection^ Connection = gcnew System::Data::SqlClient::SqlConnection("server=MYserver,MYport;Integrated security=SSPI;Database=MYdatabase;"); // create a connection to the database 
    Connection->Open(); // open the connection to the database 

    // Setup the sql command 
    System::Data::SqlClient::SqlCommand^ Command = gcnew System::Data::SqlClient::SqlCommand("INSERT INTO MYtable VALUES(@binaryValue);", Connection); // create the sql command (the column type in MYtable is 'varbinary(MAX)') 
    System::Byte^ data = gcnew System::Byte(reinterpret_cast<unsigned char>(binaryData)); // store the binary data in a System::Byte type so the sql Command will accept it as a parameter 
    Command->Parameters->Add("@binaryValue", System::Data::SqlDbType::VarBinary, sizeOfBinaryData)->Value = data; // add the binary data to the sql command 

    // Attempt to insert the binary data into the database 
    try { 
     Command->ExecuteNonQuery(); // insert binay data into database 
     System::Windows::Forms::MessageBox::Show("IT WORKED!!!","Success", System::Windows::Forms::MessageBoxButtons::OK,System::Windows::Forms::MessageBoxIcon::Information); // tell us if we are big winners 
    } 
    catch(System::Exception^ ex) { 
     System::Windows::Forms::MessageBox::Show(ex->Message,"Error", System::Windows::Forms::MessageBoxButtons::OK,System::Windows::Forms::MessageBoxIcon::Error); // tell us why we failed 
    } 

    delete[] binaryData; // clean up 
} 

Answer 1

Ma solution: La solution ici est de changer 'données' de type 'System :: Byte ^' pour 'ensemble ^'

CODE SOLUTION:

void AddFileToDatabase() { 
    // Open the test file in binary mode and read the contents into 'binaryData' 
    unsigned char* binaryData; // holds the files binary data 
    int sizeOfBinaryData = 0; // the size of stream in bytes 

    FILE* in; fopen_s(&in,"a.txt","rb"); // open the file in binary mode 
    fseek(in,0,SEEK_END); // move to the end of the file 
    sizeOfBinaryData = ftell(in); // get the file size 
    fseek(in,0,SEEK_SET); // move to the start of the file 
    binaryData = new unsigned char[sizeOfBinaryData]; // create space for the binary data 
    fread(binaryData,sizeof(unsigned char),sizeOfBinaryData,in); // read in the binary data 
    fclose(in); // close the file 

    // Connect to the database 
    System::Data::SqlClient::SqlConnection^ Connection = gcnew System::Data::SqlClient::SqlConnection("server=MYserver,MYport;Integrated security=SSPI;Database=MYdatabase;"); // create a connection to the database 
    Connection->Open(); // open the connection to the database 

    // Setup the sql command 
    System::Data::SqlClient::SqlCommand^ Command = gcnew System::Data::SqlClient::SqlCommand("INSERT INTO Files(BYTEcolumn,SIZEcolumn) VALUES(@binaryValue,'" + sizeOfBinaryData + "');", Connection); // create the sql command 
    array<System::Byte>^ data = gcnew array<System::Byte>(sizeOfBinaryData); // create a Byte array 
    for(int i = 0; i < sizeOfBinaryData; i++) { 
     data[i] = binaryData[i]; // store the binary data in a System::Byte array type so the sql Command will accept it as a parameter 
    } 
    Command->Parameters->Add("@binaryValue", System::Data::SqlDbType::VarBinary, sizeOfBinaryData)->SqlValue = data; // add the binary data to the sql command 

    // Attempt to insert the binary data into the database 
    try { 
     Command->ExecuteNonQuery(); // insert binay data into database 
     System::Windows::Forms::MessageBox::Show("IT WORKED!!!","Success", System::Windows::Forms::MessageBoxButtons::OK,System::Windows::Forms::MessageBoxIcon::Information); // tell us if we are big winners 
    } 
    catch(System::Exception^ ex) { 
     System::Windows::Forms::MessageBox::Show(ex->Message,"Error", System::Windows::Forms::MessageBoxButtons::OK,System::Windows::Forms::MessageBoxIcon::Error); // tell us why we failed 
    } 

    delete[] binaryData; // clean up 
} 

et voici comment récupérer le fichier de la base de données.

void GetFileFromDatabase() { 
    // Connect to the database 
    System::Data::SqlClient::SqlConnection^ Connection = gcnew System::Data::SqlClient::SqlConnection("server=MYserver,MYport;Integrated security=SSPI;Database=MYdatabase;"); // create a connection to the database 
    Connection->Open(); // open the connection to the database 

    // Setup the sql command 
    System::Data::SqlClient::SqlCommand^ Command = gcnew System::Data::SqlClient::SqlCommand("SELECT SIZEcolumn,BYTEcolumn FROM Files WHERE IDcolumn = MYid;", Connection); // create the sql command 

    // try to get the file from the database 
    System::Data::SqlClient::SqlDataReader^ Reader; // setup a sql data reader object to capture the data from the database 
    try { 
     Reader = Command->ExecuteReader(); // send the request to the database and put the result in the sql data reader 
     if(Reader) { // if the sql data reader has been set 
      if(!Reader->IsClosed) { // if the sql data reader is not closed 
       if(Reader->HasRows) { // if there is data in the sql data reader 
        int sizeOfBinaryData = 0; // storage for the size of the file 
        while(Reader->Read()) { // loop through the data 
         for(int i = 0;i < Reader->FieldCount; i++) { // cycle through the Size and Bytes fields of the data 
          if(!Reader->IsDBNull(i)) { // if the current data field is not emplty 

           if(Reader->GetFieldType(i)->ToString() == "System.Int32") { // if the current field is the size of the next file 
            sizeOfBinaryData = Reader->GetInt32(i); // get the size of the next file 
           }else if(Reader->GetFieldType(i)->ToString() == "System.Byte[]") { // if the current field is the byte data 
            if(sizeOfBinaryData) { // if the size of the byte data is more than 0 

             array<System::Byte>^ data = gcnew array<System::Byte>(sizeOfBinaryData); // create an Byte array to store the data 
             Reader->GetBytes(i,0,data,0,sizeOfBinaryData); // read the byte data into the Byte array 

             unsigned char* binaryData = new unsigned char[sizeOfBinaryData]; // create an unsigned char array so fwrite() will accept the array type 
             for(int i = 0; i < sizeOfBinaryData; i++) { 
              binaryData[i] = data[i]; // copy the byte data to the unsigned char array 
             } 

             // create a new file from the byte data 
             FILE* out; fopen_s(&out,"b.txt","wb"); // open the file where you want to store the data 
             fwrite(binaryData,sizeof(unsigned char),sizeOfBinaryData,out); // write the data to the new file 
             fclose(out); // close the file 
             delete[] binaryData; // clean up 
            } 
           } 
          } 
         } 
        } 
        System::Windows::Forms::MessageBox::Show("You got a new file. Good for you!","Success", System::Windows::Forms::MessageBoxButtons::OK,System::Windows::Forms::MessageBoxIcon::Error); // SUCCESS message 
       } 
      } 
      Reader->Close(); // close the sql data reader 
     } 
    }catch(System::Exception^ ex) { 
     System::Windows::Forms::MessageBox::Show(ex->Message,"Error", System::Windows::Forms::MessageBoxButtons::OK,System::Windows::Forms::MessageBoxIcon::Error); // give us error data 
    } 
} 

Merci à tous pour votre intérêt.