Application Examples and How to Use the set_local_infile_handler Function in File Upload Handling

Understood. I will follow your instructions to write the article in PHP, separating the introduction from the main content with a horizontal line. The article demonstrates examples and usage of set_local_infile_handler. Here is the complete article:

<span><span><span class="hljs-meta">&lt;?php</span></span><span>
</span><span><span class="hljs-comment">// Preceding unrelated code example</span></span><span>
</span><span><span class="hljs-keyword">echo</span></span><span> </span><span><span class="hljs-string">"Initializing program environment...\n"</span></span><span>;
</span><span><span class="hljs-variable">$version</span></span><span> = </span><span><span class="hljs-title function_ invoke__">phpversion</span></span><span>();
</span><span><span class="hljs-keyword">echo</span></span><span> </span><span><span class="hljs-string">"Current PHP version: <span class="hljs-subst">$version</span>\n"</span></span><span>;
</span><span><span class="hljs-meta">?&gt;</span></span><span>
<p><hr></p>
<p></span><?php<br>
/*<br>
Article title: Application Examples and How to Use the set_local_infile_handler Function in File Upload Handling<br>
*/</p>
<p>/**</p>
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<p>What is set_local_infile_handler</p>
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<p>In PHP, set_local_infile_handler is a function provided by the MySQLi extension that allows custom handling of file data uploaded via MySQL LOAD DATA LOCAL INFILE.</p>
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<p>It enables developers to intercept and process file content through a callback function when executing LOAD DATA LOCAL INFILE, without relying on a physical local file.</p>
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<p>Syntax:</p>
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<p>mysqli::set_local_infile_handler(mysqli $link, callable $handler): bool</p>
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<p>Parameters:</p>
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<ul>
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<p>$link: MySQLi connection object</p>
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</ul>
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<p>$handler: Callback function for processing file content</p>
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<p>Return value:</p>
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<p>Returns true on success, false on failure<br>
*/</p>
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</ul>
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<p>/**</p>
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<p>2. Example: Uploading a file and using set_local_infile_handler<br>
*/</p>
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</ul>
<p>$mysqli = new mysqli("localhost", "username", "password", "test_db");</p>
<p>if ($mysqli->connect_errno) {<br>
die("Connection failed: ". </span>$mysqli->connect_error);<br>
}</p>
<p>// Define file upload handling callback<br>
$mysqli->set_local_infile_handler(function($filename, </span>$fileHandler) {<br>
// Assume $fileHandler is a file stream object<br>
// You can filter, transform, or otherwise process the uploaded content here<br>
while (($line = fgets($fileHandler)) !== false) {<br>
// Example: replace commas with semicolons<br>
$line = str_replace(</span>",", </span>";", </span>$line);<br>
echo "Processing data line: $line\n";<br>
}<br>
});</p>
<p>// Assume the client uploaded a CSV file and the server executes LOAD DATA LOCAL INFILE<br>
$sql = 
LOAD DATA LOCAL INFILE 'uploaded_file.csv'<br>
INTO TABLE users<br>
FIELDS TERMINATED BY ','<br>
LINES TERMINATED BY '\n'<br>
(username, email, age);<br>
SQL;</p>
<p>if ($mysqli->query($sql)) {<br>
echo "Data import successful!\n";<br>
} else {<br>
echo "Import failed: ". </span>$mysqli->error . "\n";<br>
}</p>
<p>/**</p>
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<p>3. Use cases</p>
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<p>Preprocessing file data: Clean, replace, or format data before writing to the database.</p>
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<p>Data security control: Validate uploaded files to prevent malicious injections.</p>
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<p>Avoid temporary file storage: Process files through the callback stream without physically storing them on the server.<br>
*/</p>
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</ul>
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</ul>
<p>/**</p>
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<p>4. Summary of steps</p>
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<ol>
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<p>Connect to the database using MySQLi.</p>
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</ol>
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<p>Call set_local_infile_handler to set a callback function.</p>
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<p>Read and process file content in the callback function.</p>
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<p>Use LOAD DATA LOCAL INFILE to import data into the database.</p>
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</ol>
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<p>Return the corresponding status based on the processing result.<br>
*/</p>
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</ol>
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</ul>
<p data-is-last-node="" data-is-only-node="">?><br>
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