Kysely•3y ago•

11 replies

What is the suggested way of adding/removing methods to expression builders?

Context:
I am building a custom dialect for YDB https://github.com/Gaspero/kysely-ydb
YDB is slightly different from standart dialects. E.g. create/drop index expressions are a part of alter table expression (ALTER TABLE ... ADD/DROP INDEX) https://ydb.tech/en/docs/yql/reference/syntax/alter_table#secondary-index
There are also other differences that are not as critical, but I am thinking of the ways how I can protect library users from writing broken SQL queries. E.g. Insert/Replace/Update/Upsert do not support returning values and thus do not support RETURNING expression; CREATE TABLE expression only supports primary key constraint.

I've read extending Kysely section of docs https://kysely.dev/docs/recipes/extending-kysely and it looks like both options (Extending using inheritance
and Extending using module augmentation) are not advised.
I was wondering, may be there is some recommended way of modifying existing expression builders?

Regarding CREATE INDEX issue - i've managed to solve the problem not in a very elegant way but it might be non-intuitive for users familiar with YDB syntax. So I still keep looking for the idiomatic way of adding addIndex/dropIndex methods to CreateTableBuilder/AlterTableBuilder and removing .reateIndex/dropIndex from SchemaModule.

I've modified Query Compiler visitCreateIndex method


    protected override visitCreateIndex(node: CreateIndexNode): void {

    if (node.table) {
      this.append('alter table ')
      this.visitNode(node.table)
    }

    this.append(' add ')

    this.append('index ')

    this.visitNode(node.name)

    if (node.expression) {
      this.append(' global on (')
      this.visitNode(node.expression)
      this.append(')')
    }
  }


    protected override visitCreateIndex(node: CreateIndexNode): void {

    if (node.table) {
      this.append('alter table ')
      this.visitNode(node.table)
    }

    this.append(' add ')

    this.append('index ')

    this.visitNode(node.name)

    if (node.expression) {
      this.append(' global on (')
      this.visitNode(node.expression)
      this.append(')')
    }
  }

then running

await db.schema
    .createIndex('user_email_index')
    .on('users_test')
    .column('email')
    .execute()

await db.schema
    .createIndex('user_email_index')
    .on('users_test')
    .column('email')
    .execute()

results to expected sql statement

alter table

alter table

users_test

 add index

 add index

user_email_index

 global on (

 global on (

GitHub

GitHub - Gaspero/kysely-ydb

Contribute to Gaspero/kysely-ydb development by creating an account on GitHub.

Extending kysely | Kysely

In many cases Kysely doesn't provide a built-in type-safe method for a feature. It's often because adding

ALTER TABLE

Using the ALTER TABLE command, you can change the composition of columns and additional table parameters. You can specify several actions in one command. In general, the ALTER TABLE command looks like this:

Solution


    protected override visitCreateIndex(node: CreateIndexNode): void {

    if (node.table) {
      this.append('alter table ')
      this.visitNode(node.table)
    }

    this.append(' add ')

    this.append('index ')

    this.visitNode(node.name)

    if (node.expression) {
      this.append(' global on (')
      this.visitNode(node.expression)
      this.append(')')
    }
  }


    protected override visitCreateIndex(node: CreateIndexNode): void {

    if (node.table) {
      this.append('alter table ')
      this.visitNode(node.table)
    }

    this.append(' add ')

    this.append('index ')

    this.visitNode(node.name)

    if (node.expression) {
      this.append(' global on (')
      this.visitNode(node.expression)
      this.append(')')
    }
  }