通过javascript循环将文档添加到ElasticSearch索引不起作用

Question

I retrieved a lot of rows from my PostgreSQL database (stored in result.rows ) and I want to add them into my ElasticSearch index.

Add only one document works fine:

var r = result.rows[0];
esClient.index({
  index: 'families',
  type: 'families',
  id: r.family_accession,
  body: {
      'family_accession'  : r.family_accession,
      'count_seq'         : r.count_seq,
      'count_taxon'       : r.count_taxon
  }
}, function (error, response) {
  console.log(error);
});

But when I try to call it into a loop, it does not work at all:

result.rows.forEach(function (r) {
  esClient.index({
    index: 'families',
    type: 'families',
    id: r.family_accession,
    body: {
        'family_accession'  : r.family_accession,
        'count_seq'         : r.count_seq,
        'count_taxon'       : r.count_taxon
    }
  }, function (error, response) {
    console.log(error);
  });
});

Answer 1

Since you're calling an asynchronous piece of code within a loop, the context that was present when the esClient.index() function was called is not present anymore by the time your callback executes.

You need to enclose it in a closure to keep the execution context around.

result.rows.forEach(function (r) {
  (function( row ) {
    esClient.index({
      index: 'families',
      type: 'families',
      id: row.family_accession,
      body: {
          'family_accession'  : row.family_accession,
          'count_seq'         : row.count_seq,
          'count_taxon'       : row.count_taxon
      }
    }, function (error, response) {
      console.log(error);
    });
  })( r );
});