Couchbase N1QL - Nest within a Nest - couchbase

Question

Nesting within a Nest.
I've adapted my need into the following restaurant example:
Desired Output:
{
"restaurant": {
"id": "restaurant1",
"name": "Foodie",
"mains": [ // < main nested in restaurant
{
"id": "main1",
"title": "Steak and Chips",
"ingredients": [ // < ingredient nested in main (...which is nested in restaurant)
{
"id": "ingredient1",
"title": "steak"
},
{
"id": "ingredient2",
"title": "chips"
}
]
},
{
"id": "main2",
"title": "Fish and Chips",
"ingredients": [
{
"id": "ingredient3",
"title": "fish"
},
{
"id": "ingredient2",
"title": "chips"
}
]
}
]
"drinks": [ you get the idea ] // < drink nested in restaurant
}
}
Example Docs:
// RESTAURANTS
{
"id": "restaurant1",
"type": "restaurant",
"name": "Foodie",
"drinkIds": [ "drink1", "drink2" ],
"mainIds: [ "main1", "main2" ]
},
// MAINS
{
"id": "main1",
"type": "main",
"restaurantIds": [ "restaurant1" ],
"title": "Steak and Chips"
},
{
"id": "main2",
"type": "main",
"restaurantIds": [ "restaurant1" ],
"title": "Fish and Chips"
},
// INGREDIENTS
{
"id": "ingredient1",
"type": "ingredient",
"title": "steak",
"mainIds": [ "main1" ]
},
{
"id": "ingredient2",
"type": "ingredient",
"title": "chips",
"mainIds": [ "main1", "main2" ]
},
{
"id": "ingredient3",
"type": "ingredient",
"title": "fish",
"mainIds": [ "main2" ]
},
// DRINKS
{ you get the idea.... }
The closest I can get without error is:
SELECT restaurant, mains, drinks
FROM default restauant USE KEYS "restaurant1"
NEST default mains ON KEYS restaurant.mainIds
NEST default drinks ON KEYS restaurant.drinkIds;
But:
1. Obviously the nested nest is missing
2. The returned order is incorrect - the drinks nest comes first instead of last
(3. Since I'm also using Sync Gateway - it returns all the "_sync" fields with every doc - can't figure out how to omit this on each doc.)
UPDATE 1: ADAPTED SOLUTION
NB: I should have specified above that a main cannot hold ingredientIds.
Based on geraldss' v helpful input below, I added a doc which tracks keys per restaurant, eg:
{
"id": "restaurant1-JoeBloggs",
"dinerId": "JoeBloggs",
"ingredientIds": [ "ingredient1", "ingredient2" "ingredient3" ],
"mainOrdered": [ "main1" ], // < other potential uses...
"drinkOrdered": [ "drink2" ]
}
I added this to geraldss' first solution below as a JOIN to make it available to the query, eg:
SELECT *
FROM
(
SELECT
r.*,
(
SELECT
drink.*
FROM default AS drink
USE KEYS r.drinkIds
) AS drinks,
(
SELECT
main.*,
(
SELECT
ingredient.*
FROM default AS ingredient
USE KEYS keyIndex.ingredientIds // < keyIndex
WHERE ingredient.mainId=main.id
) AS ingredients
FROM default AS main
USE KEYS r.mainIds
) AS mains
FROM default AS r
USE KEYS "restaurant1"
JOIN default AS keyIndex ON KEYS "restaurant1-JoeBloggs" // < keyIndex JOINed
) AS restaurant
;
geraldss' second solution below also looks good - unfortunately it won't work for my case as this query requires that mains are found via ingredients; for my needs a main can exist without any ingredients. EDIT: > he came up with another solution. See 2.
UPDATE 2: FINAL SOLUTION
So, again, with geraldss' help I have a solution which does not require an additional doc to track keys:
SELECT *
FROM
(
SELECT
restaurant.id, restaurant.name,
(
SELECT
drink.id, drink.title
FROM default AS drink
USE KEYS restaurant.drinkIds
)
AS drinks,
(
SELECT
main.id, main.title,
ARRAY_AGG({"title":ingredient.title, "id":ingredient.id}) AS ingredients
FROM default AS ingredient
JOIN default AS main
ON KEYS ingredient.mainIds
WHERE main.restaurantId="restaurant1"
AND meta().id NOT LIKE '_sync:%' // < necessary only if using Sync Gateway
GROUP BY main
UNION ALL
SELECT
mainWithNoIngredients.id, mainWithNoIngredients.title
FROM default AS mainWithNoIngredients
UNNEST mainWithNoIngredients AS foo // < since this is being flattened the AS name is irrelevant
WHERE mainWithNoIngredients.restaurantId="restaurant1"
AND mainWithNoIngredients.type="main"
AND meta().id NOT LIKE '_sync:%' // < necessary only if using Sync Gateway
AND META(mainWithNoIngredients).id NOT IN
(
SELECT RAW mainId
FROM default AS ingredient
)
)
AS mains
FROM default AS restaurant
USE KEYS "restaurant1"
)
AS restaurant
;
NB - the AND meta().id NOT LIKE '_sync:%' lines are only necessary if using Sync Gateway.
With just 1 key I can pull all the related docs - even if they are unknown to the immediate 'parent'.
Thank you geraldss.

Answer 1

If the mains contain ingredientIds:
SELECT *
FROM
(
SELECT
r.*,
(
SELECT
drink.*
FROM default AS drink
USE KEYS r.drinkIds
) AS drinks,
(
SELECT
main.*,
(
SELECT
ingredient.*
FROM default AS ingredient
USE KEYS main.ingredientIds
) AS ingredients
FROM default AS main
USE KEYS r.mainIds
) AS mains
FROM default AS r
USE KEYS "restaurant1"
) AS restaurant
;
EDIT: Updated to include mains not referenced by any ingredients.
If the mains do not contain ingredientIds:
SELECT *
FROM
(
SELECT
r.*,
(
SELECT
drink.*
FROM default AS drink
USE KEYS r.drinkIds
) AS drinks,
(
SELECT
main.*,
ARRAY_AGG(ingredient) AS ingredients
FROM default AS ingredient
JOIN default AS main
ON KEYS ingredient.mainIds
WHERE "restaurant1" IN main.restaurantIds
GROUP BY main
UNION ALL
SELECT
main.*
FROM default AS main
WHERE "restaurant1" IN main.restaurantIds
AND META(main).id NOT IN (
SELECT RAW mainId
FROM default AS ingredient
UNNEST mainIds AS mainId
)
) AS mains
FROM default AS r
USE KEYS "restaurant1"
) AS restaurant
;