Importing an existing database

Creating index.exo

The schema import subcommand allows you to create a new schema file based on an existing Postgres database. This is useful when creating a new Exograph project where a database already exists.

Create a new Exograph project and run the following command to update the src/index.exo file.

exo schema import

You can specify the database to use using either the EXO_POSTGRES_URL or DATABASE_URL environment variable or the --database option.

exo schema import --database postgres://user:password@host:port/database

By default, the index.exo file will have all access control rules set to @access(false). You can override this through the --query-access and --mutation-access options.

exo schema import --query-access true 

Here, we are allowing all queries, but no mutations.

You should examine the generated exo file, especially regarding access control rules.

Creating fragments from the database

Consider a scenario where you have a database that is used by multiple applications and you want to create a new Exograph project that works with it without letting Exograph manage the database (for example, performing migrations, etc.).

In this case, you can pass the --fragments option to the schema import subcommand. By default, it will print the fragments to stdout, but you can specify an output file using the --output (or the shorter -o) option.

exo schema import --fragments --output generated/fragments.exo

This will create a new generated/fragments.exo file that contains fragments based on the database schema.

You can then use the generated fragments to create types for your Exograph project. See Using fragments for more information.