Import a CSV into a repeater field with ACF, removing all duplicates and leaving the last entry.

acf-csv-import-no-duplicates.php

<?php
/**
 * Optionally import Press articles from CSV ACF
 *
 * @author Travis Aaron Wagner <[email protected]>
 * @return void
 */
function taxa_import_press_articles_csv() {
	$csv = get_field('articles_csv');
	if (!$csv) return;

	$csv = (string) $csv;
	$existing_articles = (array) get_field('articles');

	$csv_obj = get_field_object('articles_csv');
	$articles_obj = get_field_object('articles');

	$new_articles = array();
	$row = 0;
	if (($handle = fopen($csv, "r")) !== false) {
		while (($data = fgetcsv($handle, 1000, ",")) !== false) {
			$row++;
			if ($row === 1) continue;
			$new_articles[] = array(
				'title' => isset($data[0]) ? $data[0] : '',
				'publication' => isset($data[1]) ? $data[1] : '',
				'link' => isset($data[2]) ? $data[2] : '',
			);
		}
		fclose($handle);
	}

	// combine the existing and new articles, removing any exact duplicates
	$combined_articles = array_unique(array_merge($existing_articles, $new_articles), SORT_REGULAR);

	// check for articles with the same title and publication & store their index
	$duplicates = array();
	foreach ($combined_articles as $i => $article) {
		@$duplicates[$article['title'] . $article['publication']][] = $i;
	}

	// remove entries with the same title and publication, keeping the latest entry
	foreach ($duplicates as $duplicate) {
		if (count($duplicate) > 1) { // if duplicates exist
			$d = array_slice($duplicate, 0, -1);
			foreach ($d as $index) { // for every duplicate
				unset($combined_articles[$index]); // remove the index
			}
		}
	}

	$updated_articles = array_values($combined_articles); // reset array index

	// replace articles repeater with CSV values
	update_field($articles_obj['key'], $updated_articles);

	// clear csv upload field
	update_field($csv_obj['key'], '');
}
add_action( 'save_post', 'taxa_import_press_articles_csv', 10 );