Question

I’m trying to convert some MYSQL querys to MYSQLI, but I’m having an issue, below is part of the script I am having issues with, the script turn a query into csv:

$columns = (($___mysqli_tmp = mysqli_num_fields($result)) ? $___mysqli_tmp : false); 

// Build a header row using the mysql field names 

$rowe = mysqli_fetch_assoc($result);
$acolumns = array_keys($rowe);
$csvstring = '"=""' . implode('""","=""', $acolumns) . '"""';
$header_row = $csvstring; 

// Below was used for MySQL, Above was added for MySQLi
//$header_row = '';
//for ($i = 0; $i < $columns; $i++) {
//  $column_title = $file["csv_contain"] . stripslashes(mysql_field_name($result, $i)) . $file["csv_contain"];
//  $column_title .= ($i < $columns-1) ? $file["csv_separate"] : '';
//  $header_row .= $column_title;
//  } 
$csv_file .= $header_row . $file["csv_end_row"]; // add header row to CSV file 

// Build the data rows by walking through the results array one row at a time 
$data_rows = ''; 
while ($row = mysqli_fetch_array($result)) { 
  for ($i = 0; $i < $columns; $i++) { 
    // clean up the data; strip slashes; replace double quotes with two single quotes 
    $data_rows .= $file["csv_contain"] .$file["csv_equ"] .$file["csv_contain"] .$file["csv_contain"] . preg_replace('/'.$file["csv_contain"].'/', $file["csv_contain"].$file["csv_contain"], stripslashes($row[$i])) . $file["csv_contain"] .$file["csv_contain"] .$file["csv_contain"];
    $data_rows .= ($i < $columns-1) ? $file["csv_separate"] : ''; 
  } 
  $data_rows .= $this->csv_end_row; // add data row to CSV file 
} 
$csv_file .= $data_rows; // add the data rows to CSV file 

if ($this->debugFlag) { 
  echo "Step 4 (repeats for each attachment): CSV file built. \n\n"; 
} 

// Return the completed file 
return $csv_file; 

The problem I am having is when building a header row for the column titles mysqli doesn’t use field_names so I am fetching the column titles by using mysqli_fetch_assoc() and then implode() the array, adding the ,‘s etc for the csv.

This works but when I produce the csv I am deleting the first data row when the header is active, when I remove my header part of the script and leave the header as null I get all data rows and a blank header (As expected).

So I must be missing something when joining my header to array to the $csv_file.

Can anyone point me in the right direction?

Many Thanks

Ben

Answer 1

A third alternative is to refactor the loop body as a function, then also call this function on the first row before entering the loop. You can use fputcsv as this function.

$csv_stream = fopen('php://temp', 'r+');

if ($row = $result->fetch_assoc()) {
    fputcsv($csv_stream, array_keys($row));

    fputcsv($csv_stream, $row);
    while ($row = $result->fetch_row()) {
        fputcsv($csv_stream, $row);
    }

    fseek($csv_stream, 0);
}
$csv_data = stream_get_contents($csv_stream);
if ($this->debugFlag) { 
  echo "Step 4 (repeats for each attachment): CSV file built. \n\n"; 
} 

// Return the completed file
return $csv_data;

As this basically does the same thing as a do ... while loop, which would make more sense to use. I bring up this alternative to present the loop body refactoring technique, which can be used when a different kind of loop doesn’t make sense.

Best of all would be to use both mysqli_result::fetch_fields and fputcsv

$csv_stream = fopen('php://temp', 'r+');

$fields = $result->fetch_fields();
foreach ($fields as &$field) {
    $field = $field->name;
}
fputcsv($csv_stream, $fields);

while ($row = $result->fetch_row()) {
    fputcsv($csv_stream, $row);
}

fseek($csv_stream, 0);
$csv_data = stream_get_contents($csv_stream);
if ($this->debugFlag) { 
  echo "Step 4 (repeats for each attachment): CSV file built. \n\n"; 
} 

// Return the completed file
return $csv_data;

If you can require that PHP be at least version 5.3, you can replace the foreach that generates the header line with a call to array_map. There admittedly isn’t much advantage to this, I just find the functional approach more interesting.

fputcsv($csv_stream, 
        array_map(function($field) {return $field->name}, 
                  $result->fetch_fields()));