Question

I want to have a SelectAll function which takes in a few arguments (class, table, sort field, and sort order.) The comments explain what is going on (or what is supposed to.)

  public static function SelectAll($class, $table, $sort_field, $sort_order = "ASC")
  {

    /* First, the function performs a MySQL query using the provided arguments. */

    $query = "SELECT * FROM " .$table. " ORDER BY " .$sort_field. " " .$sort_order;
    $result = mysql_query($query);

    /* Next, the function dynamically gathers the appropriate number and names of properties. */

    $num_fields = mysql_num_fields($result);
    for($i=0; $i < ($num_fields); $i++)
    {
      $fetch = mysql_fetch_field($result, $i);
      $properties[$i] = "'".$fetch->name."'";
    }
    /*echo [$properties[0]; echo "<br />";}*/
    /* Finally, the function produces and returns an array of constructed objects. */

    while($row = mysql_fetch_assoc($result))
    { 
      for($i=0; $i < ($num_fields); $i++)
      {
        $args[$i] = $row[$properties[$i]];
      }
      $array[] = call_user_func_array(new $class, $args);
    } return $array; }

Now, the problem I am having is that $row[$properties[$i]] results in ‘undefined index.’

Right after the function gathers the number/names of the fields and stores them in an array, I can echo the value of $properties[0] and it shows as it should, ‘id’, but $row[~anything here~] will simply not work unless I manually enter the value, such as $row['id']. As you can imagine very frustrating and confusing.

Why won’t this work? Are there any solutions, or alternate ways of accomplishing this function?

Answer 1

As I see your $properties[$i] array items have quoted values like "'id'",
so $row[$properties[$i]] <==> $row["'id'"] != $row["id"];

And you might want to check $result === false after $result = mysql_query($query);

Anyway, I think you could replace your function to this (unless you constructed it for demonstration only):

public static function SelectAll($class, $method_name, $table, $sort_field, $sort_order = "ASC"){
  /* First, the function performs a MySQL query using the provided arguments. */
  $query = "SELECT * FROM " .$table. " ORDER BY " .$sort_field. " " .$sort_order;
  $result = mysql_query($query);

  while($row = mysql_fetch_array($result))
    $array[] = call_user_func_array(array($class,'__construct'), $row);

  return $array;
}