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What is the method for versioning multiple tables using Dexie 3.0, considering that users can switch from any previous version to the newest one?

asked 2021-07-14 11:00:00 +0000

qstack gravatar image

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answered 2022-02-25 13:00:00 +0000

huitzilopochtli gravatar image

The method for versioning multiple tables using Dexie 3.0 while allowing users to switch from any previous version to the newest one involves the following steps:

  1. Define the initial database schema with all the tables and their columns using the version() method.

  2. Whenever there is a change to the database schema, create a new schema object with the updated tables and columns using the version() method and increment the version number.

  3. Define a migration() function for each version that upgrades or downgrades the database schema by adding, removing or modifying tables and their columns. This function should return a promise that resolves when the migration is complete.

  4. Use the open() method to open the database, providing the latest version number and an object that maps older versions to their corresponding migration functions. This allows Dexie to automatically transition the database schema between versions as needed.

  5. When a user switches to a previous version, Dexie automatically applies the required migrations to downgrade the schema to that version. Similarly, when a user switches to the newest version, Dexie applies any required migrations to upgrade the schema to that version.

Here is a sample code snippet that illustrates these steps:

const db = new Dexie('myDatabase');
db.version(1).stores({
  table1: '++id, col1, col2',
  table2: '++id, col1, col2, col3'
});

db.version(2).stores({
  table1: '++id, col1, col2, col3',
  table2: '++id, col1, col2, col3, col4',
  table3: '++id, col1, col2, col3, col5'
}).upgrade((trans) => {
  // Add or modify tables and columns here
  // Use trans.table('tableName').addIndex('indexName', 'columns')
  // to add new indexes to tables
});

db.version(3).stores({
  table1: '++id, col1, col2, col3, col4',
  table2: '++id, col1, col2, col3, col4, col5'
}).upgrade((trans) => {
  // Another upgrade method example
});

// Open the database with the latest version and migration map
db.open({
  version: db.verno,
  // Migration map maps old versions to their corresponding migration functions
  migrations: {
    1: (trans) => {
      // Migration function for version 1
    },
    2: (trans) => {
      // Migration function for version 2
    }
  }
});

// Switch to previous version
db.open(1).then(() => {
  // Database is now downgraded to version 1
});

// Switch to latest version
db.open().then(() => {
  // Database is now upgraded to the latest version
});
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Asked: 2021-07-14 11:00:00 +0000

Seen: 9 times

Last updated: Feb 25 '22