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Overriding types

In many cases it's useful to tell sqlc explicitly what Go type you want it to use for a query input or output. For instance, a PostgreSQL UUID type will map to UUID from github.com/jackc/pgx/pgtype by default when you use pgx/v5, but you may want sqlc to use UUID from github.com/google/uuid instead.

If you'd like sqlc to use a different Go type, specify the package import path and type in the overrides list.

version: "2"
sql:
- schema: "postgresql/schema.sql"
  queries: "postgresql/query.sql"
  engine: "postgresql"
  gen:
    go: 
      package: "authors"
      out: "db"
      sql_package: "pgx/v5"
      overrides:
        - db_type: "uuid"
          go_type:
            import: "github.com/google/uuid"
            type: "UUID"

The overrides list

Each element in the overrides list has the following keys:

  • db_type:
    • A database type to override. Find the full list of supported types in postgresql_type.go or mysql_type.go. Note that for Postgres you must use pg_catalog-prefixed names where available. db_type and column are mutually exclusive.
  • column:
    • A column name to override. The value should be of the form table.column but you can also specify schema.table.column or catalog.schema.table.column. column and db_type are mutually exclusive.
  • go_type:
    • The fully-qualified name of a Go type to use in generated code. This is usually a string but can also be a map for more complex configurations.
  • go_struct_tag:
    • A reflect-style struct tag to use in generated code, e.g. a:"b" x:"y,z". If you want json or db tags for all fields, use emit_json_tags or emit_db_tags instead.
  • unsigned:
    • If true, sqlc will apply this override when a numeric db_type is unsigned. Note that this has no effect on column overrides. Defaults to false.
  • nullable:
    • If true, sqlc will apply this override when a column is nullable. Otherwise sqlc will apply this override when a column is non-nullable. Note that this has no effect on column overrides. Defaults to false.

Note that a single db_type override configuration applies to either nullable or non-nullable columns, but not both. If you want the same Go type to override in both cases, you'll need to configure two overrides.

When generating code, entries using the column key will always take precedence over entries using the db_type key.

The go_type map

Some overrides may require more detailed configuration. If necessary, go_type can be a map with the following keys:

  • import:
    • The import path for the package where the type is defined.
  • package:
    • The package name where the type is defined. This should only be necessary when your import path doesn't end with the desired package name.
  • type:
    • The type name itself, without any package prefix.
  • pointer:
    • If true, generated code will use a pointer to the type rather than the type itself.
  • slice:
    • If true, generated code will use a slice of the type rather than the type itself.

An example:

version: "2"
sql:
- schema: "postgresql/schema.sql"
  queries: "postgresql/query.sql"
  engine: "postgresql"
  gen:
    go: 
      package: "authors"
      out: "db"
      sql_package: "pgx/v5"
      overrides:
        - db_type: "uuid"
          go_type:
            import: "a/b/v2"
            package: "b"
            type: "MyType"
            pointer: true