how can we check whether a table already exists or not, in typeorm?-CodePudding

postgresql, typeorm how can we check whether a table already exists in a database before starting database operations on that table?

currently my code is like this, i check whether an item is present in database. But the problem with this approach is that, if its a fresh deployment, and if the tables are not present, then an exception is thrown.

const found = await this.userRepository.findOne(undefined);   //<<< throws exception if tables not already created

if (found === undefined) {
    const item: Items = this.userRepository.create({....});
}

so how can we add a check for a table's existance first, before doing database operations on it?

CodePudding user response：

If you can use raw SQL queries for this, you can get the Entity Manager from the User Repository and run a query to check the information schema. Just replace the following snippet with your SCHEMA_NAME and TABLE_NAME.

const tableExists = (
  await this.userRepository.manager.query(
    `SELECT exists (
      SELECT FROM information_schema.tables
        WHERE  table_schema = 'SCHEMA_NAME'
        AND    table_name   = 'TABLE_NAME'
        )`,
  )
)[0].exists;

Adapted from this answer.