Functions which can be used inside a query

Here is the list of functions that can be used inside a generator query:

• avg()

• abs()

• exists()

• len()

• max()

• min()

• count()

• concat()

• group_concat()

• random()

• raw_sql()

• select()

• sum()

• getattr()

Examples:

select(avg(c.orders.total_price) for c in Customer)

SELECT AVG("order-1"."total_price")
FROM "Customer" "c"
  LEFT JOIN "Order" "order-1"
    ON "c"."id" = "order-1"."customer"

select(o for o in Order if o.customer in
       select(c for c in Customer if c.name.startswith('A')))[:]

SELECT "o"."id", "o"."state", "o"."date_created", "o"."date_shipped",
       "o"."date_delivered", "o"."total_price", "o"."customer"
FROM "Order" "o"
WHERE "o"."customer" IN (
    SELECT "c"."id"
    FROM "Customer" "c"
    WHERE "c"."name" LIKE 'A%'
    )

Using getattr()

getattr() is a built-in Python function, that can be used for getting the attribute value.

Example:

attr_name = 'name'
param_value = 'John'
select(c for c in Customer if getattr(c, attr_name) == param_value)