Preload with joins - aavedula/how-to-notes GitHub Wiki

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Rails command

  Member.joins(:population).preload(:population)

SQL Query

  Member Load (0.6ms)

  SELECT "members".*
  FROM "members"
  INNER JOIN "populations"
  ON "populations"."id" = "members"."population_id"

  Population Load (0.5ms)

  SELECT "populations".*
  FROM "populations"
  WHERE "populations"."id" IN ($1, $2, $3, $4, $5, $6, $7)  
    [["id", "B000NKUUKW"],
    ["id", "B000CDC7O2"],
    ["id", "B0000VG5MG"],
    ["id", "B000A70EOU"],
    ["id", "B000Q71WNG"],
    ["id", "B00067Q8TY"],
    ["id", "B000662QI2"]]

Return value

Loads populations, returns Members