Using SQLite Dates in a React Native app


When I first began working with SQLite I was surprised to learn that there was no DATE or DATETIME datatype equivalent. Instead, time-based data must be stored as INTEGER, TEXT or REAL types. But, how can you logically order a TEXT-based date? How can you move seamlessly between Moment.js on the clientside and these primitive types in SQLite? Read on!

Create table

If you’d like to store a date, like June 27th 2019, I would recommend using the TEXT datatype and providing it with date strings in the following format: YYYY-MM-DD. There are other formats (look for “Time Strings”) you can use when you need to store time of day as well, such as YYYY-MM-DD HH:MM:SS.

You can create a table with a column of this type during app initialization:

tx.executeSql("CREATE TABLE IF NOT EXISTS Transaction( " +
  "id INTEGER PRIMARY KEY NOT NULL, " +
  /* other columns... */
  "transactionDate TEXT" +
  ");"
);

The table will be created if it does not already exist.

Insert

Later on, when you’d like to write to this table, craft an INSERT statement that formats your Moment object into a string matching one of the supported SQLite time string formats:

function insertTransaction(transactionDate: moment.Moment, tx) {
  return tx.executeSql(
    // Other columns removed to simplify example
    "INSERT INTO Transaction (transactionDate) VALUES (?)",
    [transactionDate.format("YYYY-MM-DD")]
  )
}

Select

To read your date values back from the DB, craft a query that returns the column as a string and create a new Moment from it’s value:

function getTransactions(tx): Promise<Transaction[]> {
  return tx.executeSql(
    "SELECT id, transactionDate " +
    /* other columns... */
    "FROM Transaction " +
    /* WHERE... */
    /* 1. Note date() function call */
    "ORDER BY date(transactionDate) ASC;"
  )
  .then(([results]) => {
    if (results === undefined) return [];
    
    // Build the array of transactions
    const transactions: Transaction[] = [];
    for (let i = 0; i < results.rows.length; i++) {
      const row = results.rows.item(i);
      transactions.push(
        newTransactionFromObject(row)
      );
    }
    return transactions;
  });
}

function newTransactionFromObject(row): Transaction {
  // 2. Create a new Moment from the transactionDate string
  const transactionDate = row.transactionDate ? moment(row.transactionDate) : null;
  return new Transaction(row.id, transactionDate);
}

There are a couple of things happening in the code above:

  1. Note the date(transactionDate) function call. This enables us to ORDER BY based on the date, amongst other date-related things. In this example the transactions will be ordered oldest to newest.
  2. We can conditionally create a new Moment instance if the row’s transactionDate is defined. Otherwise, it will be null.

You now have a date value available for use on the app’s client side, in the super flexible and versatile Moment type.

Further reading

I’ve written a couple of other posts on the topic of SQLite and React Native. Check out: