How to convert blob to base64 in php

In actual development, we sometimes need to convert some binary streams into string form, such as converting pictures into string form and saving them in the database. In PHP, we can use blob fields to save binary streams, but sometimes we need to convert blob fields into base64 encoding for display in web pages. In this article, we will discuss how to convert blob fields to base64 encoding in PHP.

First, we need to read the binary data of the blob field from the database. We can use PHP's PDO extension to operate the database. The following is a simple sample code:

try {
  $dbh = new PDO("mysql:host=localhost;dbname=test", $user, $pass);
  $stmt = $dbh->prepare("SELECT image FROM images WHERE id = ?");
  $stmt->bindParam(1, $id);
  $stmt->execute();
  $image = $stmt->fetchColumn();
  $dbh = null;
} catch (PDOException $e) {
  print "Error!: " . $e->getMessage() . "<br>";
  die();
}

In the above code, we use the PDO prepared statement to read the image field data in the record with id $id from the database. The $image variable will hold the binary data stream.

Next, we need to convert the binary data stream to base64 encoding. PHP's built-in base64_encode() function can achieve this function. The following is a sample code:

$base64_image = base64_encode($image);

Convert the binary data stream $image to base64 encoding and save it in the $base64_image variable.

Finally, we can use base64 encoded image data in web pages. The following is sample code:

<img  src="/static/imghwm/default1.png" data-src="data:image/jpeg;base64,<?php echo $base64_image; ?>" class="lazy" alt="How to convert blob to base64 in php" >

The above code will display an image in the browser. Among them, data:image/jpeg;base64, represents the encoding format of the image and the base64-encoded image data.

During development, we can use the above method to convert the blob field into base64 encoding for display on the web page. This avoids the need to download images from the server every time the page is opened. At the same time, server bandwidth and resources can also be saved.

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