Function buildIncludesSubquery

packages/db/src/query/builder/index.ts:1122–1317

* Builds an IncludesSubquery IR node from a child query builder. * Extracts the correlation condition from the child's WHERE clauses by finding * an eq() predicate that references both a parent alias and a child alias.

(
  childBuilder: BaseQueryBuilder,
  fieldName: string,
  parentAliases: Array<string>,
  materialization: IncludesMaterialization,
)

 * an eq() predicate that references both a parent alias and a child alias.
 */
function buildIncludesSubquery(
  childBuilder: BaseQueryBuilder,
  fieldName: string,
  parentAliases: Array<string>,
  materialization: IncludesMaterialization,
): IncludesSubquery {
  const childQuery = childBuilder._getQuery()

  // Collect child's own aliases
  const childAliases = collectQueryAliases(childQuery)

  // Walk child's WHERE clauses to find the correlation condition.
  // The correlation eq() may be a standalone WHERE or nested inside a top-level and().
  let parentRef: PropRef | undefined
  let childRef: PropRef | undefined
  let correlationWhereIndex = -1
  let correlationAndArgIndex = -1 // >= 0 when found inside an and()

  if (childQuery.where) {
    for (let i = 0; i < childQuery.where.length; i++) {
      const where = childQuery.where[i]!
      const expr =
        typeof where === `object` && `expression` in where
          ? where.expression
          : where

      // Try standalone eq()
      if (
        expr.type === `func` &&
        expr.name === `eq` &&
        expr.args.length === 2
      ) {
        const result = extractCorrelation(
          expr.args[0]!,
          expr.args[1]!,
          parentAliases,
          childAliases,
        )
        if (result) {
          parentRef = result.parentRef
          childRef = result.childRef
          correlationWhereIndex = i
          break
        }
      }

      // Try inside top-level and()
      if (
        expr.type === `func` &&
        expr.name === `and` &&
        expr.args.length >= 2
      ) {
        for (let j = 0; j < expr.args.length; j++) {
          const arg = expr.args[j]!
          if (
            arg.type === `func` &&
            arg.name === `eq` &&
            arg.args.length === 2