修改函数动态填充选择要使用数组的数据库

Question

我试图修改一个函数，我一直在使用动态填充<select>元素来使用数据库中的数组。原始函数使用硬编码数组来填充元素，并预先选择了与db值相匹配的选项。

修改后的函数创建元素，但它只是从db中添加第一个值。我怎样才能修改它，以便循环遍历所有应该添加到<select>元素的值？

PHP函数和查询

<?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(); 
?> 

填充选择元素

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

原有功能&代码填入一元

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

由于您只通过fetch()获取了单个行，因此只有一个值传入您的函数printSelectOptions()。取而代之，通过fetchAll() 获取所有行并修改您的函数以接收完整阵列，再加上字符串，这是您要打印的列名称（数组键）。

// 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; 
} 

然后调用该函数为：

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

它是现在，期权的价值属性由数组键，这将从零开始编号填充的方式。这与您的原始数组版本类似，但指定另一个列名称（如id）作为关键列可能更有用。

// 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; 
} 

，并会被称为：

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