# Working with dates

In this guide, you will learn about Meilisearch's approach to date and time values, how to prepare your dataset for indexing, and how to chronologically sort and filter search results.

# Preparing your documents

To filter and sort search results chronologically, your documents must have at least one numeric field containing a UNIX timestamp (opens new window).

As an example, consider a database of video games. In this dataset, the release year is formatted as a timestamp:

[
  {
    "id": 0,
    "title": "Return of the Obra Dinn",
    "genre": "adventure",
    "release_timestamp": 1538949600
  },
  {
    "id": 1,
    "title": "The Excavation of Hob's Barrow",
    "genre": "adventure",
    "release_timestamp": 1664316000
  },
  {
    "id": 2,
    "title": "Bayonetta 2",
    "genre": "action",
    "release_timestamp": 1411164000
  }
]

If your date field is expressed in a format other than a numeric timestamp, like ISO 8601 (opens new window), you must convert it before indexing it with Meilisearch.

Most programming languages have built-in tools to help you with this process. The JavaScript example below converts a game's release date, "2018-10-18", to a numeric timestamp:

let game = {
  "id": 0,
  "title": "Return of the Obra Dinn",
  "genre": "adventure",
  "release_date": "2018-10-18T00:00Z"
};

const timestampInMilliseconds = Date.parse(game.release_date); // Date.parse returns the timestamp in milliseconds
const timestamp = timestampInMilliseconds / 1000; // UNIX timestamps must be in seconds

game = {
  "id": 0,
  "title": "Return of the Obra Dinn",
  "genre": "adventure",
  "release_date": "2018-10-18T00:00Z",
  "release_timestamp": timestamp
};

TIP

When preparing your dataset, it can be useful to leave the original date and time fields in your documents intact. In the example above, we keep the release_date field because it is more readable than the raw release_timestamp.

After adding a numeric timestamp to all documents, index your data as usual. The example below adds a videogame dataset to a games index:

curl \
  -x post 'http://localhost:7700/indexes/games/documents' \
  -h 'content-type: application/json' \
  --data-binary @games.json

# Filtering by timestamp

To filter search results based on their timestamp, add your document's timestamp field to the list of filterableAttributes:

curl \
  -X PUT 'http://localhost:7700/indexes/games/settings/filterable-attributes' \
  -H 'Content-Type: application/json' \
  --data-binary '[
    "release_timestamp"
  ]'

Once you have configured filterableAttributes, you can filter search results by date. The following query only returns games released between 2018 and 2022:

curl \
  -X POST 'http://localhost:7700/indexes/games/search' \
  -H 'Content-Type: application/json' \
  --data-binary '{
    "q": "",
    "filter": "release_timestamp >= 1514761200 AND release_timestamp < 1672527600"
  }'

# Sorting by timestamp

To sort search results chronologically, add your document's timestamp field to the list of sortableAttributes:

curl \
  -X PUT 'http://localhost:7700/indexes/games/settings/sortable-attributes' \
  -H 'Content-Type: application/json' \
  --data-binary '[
    "release_timestamp"
  ]'

Once you have configured sortableAttributes, you can sort your search results based on their timestamp. The following query returns all games sorted from most recent to oldest:

curl \
  -X POST 'http://localhost:7700/indexes/games/search' \
  -H 'Content-Type: application/json' \
  --data-binary '{
    "q": "",
    "sort": ["release_timestamp:desc"]
  }'