Programmatically accessing block content

Question

Could anyone tell me how to programmatically access the field content of a custom block?

Thus far I've managed:

use Drupal\block\Entity\Block;
$block = Block::load($block_name);

if ($block) {
  $render = \Drupal::entityTypeManager()
    ->getViewBuilder('block')
    ->view($block);
}

However this doesn't give me access to the fields and their data.

Answer 1

Your code loads a configured block, not the content of a custom block.

This will load the field data of block content:

$custom_block = \Drupal::entityTypeManager()->getStorage('block_content')->load('1');
$fieldcontent = $custom_block->field_myfield->value;

Answer 2

I just wanted to explain the example code given in the other answer with more detail, which will save time to many users.

$custom_block = \Drupal::entityTypeManager()->getStorage('block_content')->load('1');
$fieldcontent = $custom_block->field_myfield->value;

1. block_content is a database table in your Drupal project
2. 1 in load('1') is the ID value from that table
3. field_myfield is a table field from the block_content__body table, for example block_content__body.body_value

If you want to change data from block_content__body.body_value field in your block, simply use this code.

$custom_block->body->value = 'TEST';