Method RequestData

IO/PostgreSQL/vtkPostgreSQLToTableReader.cxx:28–143

------------------------------------------------------------------------------

//------------------------------------------------------------------------------
int vtkPostgreSQLToTableReader::RequestData(
  vtkInformation*, vtkInformationVector**, vtkInformationVector* outputVector)
{
  // Make sure we have all the information we need to provide a vtkTable
  if (!this->Database)
  {
    vtkErrorMacro(<< "No open database connection");
    return 1;
  }
  if (!this->Database->IsA("vtkPostgreSQLDatabase"))
  {
    vtkErrorMacro(<< "Wrong type of database for this reader");
    return 1;
  }
  if (this->TableName.empty())
  {
    vtkErrorMacro(<< "No table selected");
    return 1;
  }

  vtkInformation* outInfo = outputVector->GetInformationObject(0);

  // Return all data in the first piece ...
  if (outInfo->Get(vtkStreamingDemandDrivenPipeline::UPDATE_PIECE_NUMBER()) > 0)
  {
    return 1;
  }

  vtkTable* const output = vtkTable::SafeDownCast(outInfo->Get(vtkDataObject::DATA_OBJECT()));

  // perform a query to get the names and types of the columns
  std::string queryStr =
    "select column_name, data_type FROM information_schema.columns WHERE table_name = '";
  queryStr += this->TableName;
  queryStr += "';";
  vtkPostgreSQLQuery* query = static_cast<vtkPostgreSQLQuery*>(this->Database->GetQueryInstance());
  query->SetQuery(queryStr.c_str());
  if (!query->Execute())
  {
    vtkErrorMacro(<< "Error performing 'show columns' query");
  }

  // use the results of the query to create columns of the proper name & type
  std::vector<std::string> columnTypes;
  while (query->NextRow())
  {
    std::string columnName = query->DataValue(0).ToString();
    std::string columnType = query->DataValue(1).ToString();
    if ((columnType.find("int") != std::string::npos) ||
      (columnType.find("INT") != std::string::npos) ||
      (columnType.find("serial") != std::string::npos) ||
      (columnType.find("SERIAL") != std::string::npos))
    {
      vtkSmartPointer<vtkIntArray> column = vtkSmartPointer<vtkIntArray>::New();
      column->SetName(columnName.c_str());
      output->AddColumn(column);
      columnTypes.emplace_back("int");
    }