Method join

packages/db/src/query/builder/index.ts:262–315

* Join another table or subquery to the current query * * @param source - An object with a single key-value pair where the key is the table alias and the value is a Collection or subquery * @param onCallback - A function that receives table references and returns the join condition * @pa

(
    source: TSource,
    onCallback: JoinOnCallback<
      MergeContextForJoinCallback<TContext, SchemaFromSource<TSource>>
    >,
    type: TJoinType = `left` as TJoinType,
  )

   *   .join({ p: postsCollection }, ({u, p}) => eq(u.id, p.userId))
   */
  join<
    TSource extends Source,
    TJoinType extends `inner` | `left` | `right` | `full` = `left`,
  >(
    source: TSource,
    onCallback: JoinOnCallback<
      MergeContextForJoinCallback<TContext, SchemaFromSource<TSource>>
    >,
    type: TJoinType = `left` as TJoinType,
  ): QueryBuilder<
    MergeContextWithJoinType<TContext, SchemaFromSource<TSource>, TJoinType>
  > {
    const [alias, from] = this._createRefForSource(source, `join clause`)

    // Create a temporary context for the callback
    const currentAliases = this._getCurrentAliases()
    const newAliases = [...currentAliases, alias]
    const refProxy = createRefProxy(newAliases) as RefsForContext<
      MergeContextForJoinCallback<TContext, SchemaFromSource<TSource>>
    >

    // Get the join condition expression
    const onExpression = onCallback(refProxy)

    // Extract left and right from the expression
    // For now, we'll assume it's an eq function with two arguments
    let left: BasicExpression
    let right: BasicExpression

    if (
      onExpression.type === `func` &&
      onExpression.name === `eq` &&
      onExpression.args.length === 2
    ) {
      left = onExpression.args[0]!
      right = onExpression.args[1]!
    } else {
      throw new JoinConditionMustBeEqualityError()
    }

    const joinClause: JoinClause = {
      from,
      type,
      left,
      right,
    }

    const existingJoins = this.query.join || []

    return new BaseQueryBuilder({
      ...this.query,
      join: [...existingJoins, joinClause],
    }) as any
  }

  /**
   * Perform a LEFT JOIN with another table or subquery