OperationNodeTransformer

Transforms an operation node tree into another one.

Kysely queries are expressed internally as a tree of objects (operation nodes). OperationNodeTransformer takes such a tree as its input and returns a transformed deep copy of it. By default the OperationNodeTransformer does nothing. You need to override one or more methods to make it do something.

There's a method for each node type. For example if you'd like to convert each identifier (table name, column name, alias etc.) from camelCase to snake_case, you'd do something like this:

class CamelCaseTransformer extends OperationNodeTransformer {
  transformIdentifier(node: IdentifierNode): IdentifierNode {
    node = super.transformIdentifier(node),

    return {
      ...node,
      name: snakeCase(node.name),
    }
  }
}

const transformer = new CamelCaseTransformer()
const tree = transformer.transformNode(tree)