修改函數動態填充選擇要使用數組的數據庫

Question

我試圖修改一個函數，我一直在使用動態填充<select>元素來使用數據庫中的數組。原始函數使用硬編碼數組來填充元素，並預先選擇了與db值相匹配的選項。

修改後的函數創建元素，但它只是從db中添加第一個值。我怎樣才能修改它，以便循環遍歷所有應該添加到<select>元素的值？

PHP函數和查詢

<?php 
function printSelectOptions($dataArray, $currentSelection) { 
    foreach ($dataArray as $key => $value) { 
     echo '<option ' . (($key == $currentSelection)) . ' value="' . $key . '">' . $value . '</option>'; 
    } 
} 
try { 
    $stmt = $conn->prepare("SELECT * FROM student"); 
    $stmt->execute(); 
    }catch(PDOException $e) { 
    echo $e->getMessage(); 
} 
$row = $stmt->fetch(); 
?> 

填充選擇元素

<select name="fname"> 
    <?php 
     echo printSelectOptions(array($row['fname'])); 
    ?> 
</select> 

原有功能&代碼填入一元

function printSelectOptions($dataArray, $currentSelection) { 
    foreach ($dataArray as $key => $value) { 
     echo '<option ' . (($key == $currentSelection) ? 'selected="selected"' : '') . ' value="' . $key . '">' . $value . '</option>'; 
    } 
} 

<select name="fname"> 
    <?php 
     $options = array("John"=>"John", "Mary"=>"Mary", "Elizabeth"=>"Elizabeth"); 
     $selected = $row['fname']; 
     echo printSelectOptions($options, $selected); 
    ?> 
</select> 

Answer 1

由於您只通過fetch()獲取了單個行，因此只有一個值傳入您的函數printSelectOptions()。取而代之，通過fetchAll() 獲取所有行並修改您的函數以接收完整陣列，再加上字符串，這是您要打印的列名稱（數組鍵）。

// All rows into $rows... 
$rows = $stmt->fetchAll(); 

// Make the function accept the full 2D array, and 
// a string key which is the field name to list out: 
function printSelectOptions($dataArray, $currentSelection, $fieldname) { 
    // String to hold output 
    $output = ''; 
    foreach ($dataArray as $key => $value) { 
     // Rather than echo here, accumulate each option into the $output string 
     // Use the $fieldname as a key to $value which is now an array... 
     $output .= '<option ' . (($key == $currentSelection)) . ' value="' . $key . '">' . htmlspecialchars($value[$fieldname], ENT_QUOTES) . '</option>'; 
    } 
    return $output; 
} 

然後調用該函數爲：

echo printSelectOptions($rows, $currentSelection, 'fname'); 

它是現在，期權的價值屬性由數組鍵，這將從零開始編號填充的方式。這與您的原始數組版本類似，但指定另一個列名稱（如id）作爲關鍵列可能更有用。

// This one also takes a $valuename to use in place of $key... 
function printSelectOptions($dataArray, $currentSelection, $valuename, $fieldname) { 
    // String to hold output 
    $output = ''; 
    foreach ($dataArray as $key => $value) { 
     // Rather than echo here, accumulate each option into the $output string 
     // Use the $fieldname as a key to $value which is now an array... 
     $output .= '<option ' . (($value[$valuename] == $currentSelection)) . ' value="' . $value[$valuename] . '">' . htmlspecialchars($value[$fieldname], ENT_QUOTES) . '</option>'; 
    } 
    return $output; 
} 

，並會被稱爲：

echo printSelectOptions($rows, $currentSelection, 'id', 'fname');