I have a json file like this

  "online": false,
  "key": "123",
  "Product": {
    "name": "product name",
    "Id": 12,

I have my json migration file

  plugin: url
  data_fetcher_plugin: file
  data_parser_plugin: json
    - 'json_path/data.json'
  item_selector: /Product
    - name: keyword
      label: 'Keyword'
      selector: name
      type: string
    vocabulary: tag
  vid: constants/vocabulary
  name: keyword
  plugin: entity:taxonomy_term

but I am getting the following error.

Drupal\Core\Database\IntegrityConstraintViolationException: SQLSTATE[23000]: Integrity constraint violation: 1048 Column 'name' cannot be null

It means the xpath is not correct.

I have tried with the item_selector: $ and for the keyword selector selector: Product.name but then I am getting this error.

Passed variable is not an array or object

I have tried with item_selector: 0 and item_selector: / but nothing worked.

However when I use the following json.

  "online": false,
  "key": "123",
  "Product": [
      "name": "product name",
      "Id": 12,

Notice the [] brackets.

What is the issue? How can I make it work without the [] brackets because I don't have any control on the json to change it.

1 Answer 1


The data_parser_plugin: json always expects an array with numeric keys as item_selector, there is no way you can get around this requirement in YAML. If you want to use a single object as item_selector, you have to create your own data_parser_plugin.

I've already had that problem in a previous object and creates my custom plugin and used my custom data_parser_plugin: single_json_object in YAML instead.

file MY_MODULE/src/Plugin/migrate_plus/data_parser/SingleJsonObject.php


namespace Drupal\MY_MODULE\Plugin\migrate_plus\data_parser;

use Drupal\migrate_plus\Plugin\migrate_plus\data_parser\Json;

 * Obtain JSON data for migration.
 * @DataParser(
 *   id = "single_json_object",
 *   title = @Translation("Single JSON object as root")
 * )
class SingleJsonObject extends Json {

  protected function has_string_keys(array $array) {
    return count(array_filter(array_keys($array), 'is_string')) > 0;

  protected function getSourceData($url) {
    $source_data = parent::getSourceData($url);

    if ($this->has_string_keys($source_data)) {
      $sequential_array = [];
      $sequential_array[] = $source_data;
      $source_data = $sequential_array;

    return $source_data;
  • what will be the value of the item_selector then? and the keyword selector?
    – Ahmad
    Dec 10, 2020 at 11:42
  • I have used item_selecotr: / and the keyword selector as selector: Product/name and it worked for me with your data parser plugin
    – Ahmad
    Dec 10, 2020 at 12:41

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