Export Incorrectly Lists 0 index fields as null instead of false or empty array

Author: lgtmakCreated Aug 7, 2025Updated Sep 7, 2025

javascript

// config
{
  document: {
    id: "id",
    store: true,
    index: [
      { field: "title", tokenize: "forward" },
    ],
    tag: [ { field: "scoredValue", custom: (data) => Number(data.score) > 1 ? ">1" : false } ]
  }
}

// sample docs
[
  {
    "id": 1,
    "title": "One",
    "score":  null,
  },
  {
    "id": 2,
    "title": "Two",
    "score":  null,
  },
]

When exporting the database it will produce an index json like this:

javascript

{
  ...
  "1.tag": "[[\"scoredValue\", null],[...],[...]]
}

When I attempt to import I get this error on the 1.tag key:

TypeError: Cannot read properties of null (reading 'length')

Import code:

javascript

const docIndex = new Document(name, myConfig);
// where key is `1.tag` from index export
for (const key in blobData.indexes) {
    docIndex.import(key, blobData.indexes[key]);
}

Source: nextapps-de/flexsearch

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