For

EdgeQL supports a top-level for statement. These “for loops” iterate over each element of some input set, execute some expression with it, and merge the results into a single output set.

db> 
... 
... 
...

for number in {0, 1, 2, 3}
union (
  select { number, number + 0.5 }
);

{0, 0.5, 1, 1.5, 2, 2.5, 3, 3.5}

This statements iterates through each number in the set. Inside the loop, the number variable is bound to a singleton set. The inner expression is executed for every element of the input set, and the results of each execution are merged into a single output set.

The union keyword is a required part of the for statement syntax; it is intended to indicate explicitly that the results of each loop execution are ultimately merged.

Bulk inserts

The for statement is commonly used for bulk inserts.

db> 
... 
... 
...

for hero_name in {'Cersi', 'Ikaris', 'Thena'}
union (
  insert Hero { name := hero_name }
);

{
  default::Hero {id: d7d7e0f6-40ae-11ec-87b1-3f06bed494b9},
  default::Hero {id: d7d7f870-40ae-11ec-87b1-f712a4efc3a5},
  default::Hero {id: d7d7f8c0-40ae-11ec-87b1-6b8685d56610}
}

This statements iterates through each name in the list of names. Inside the loop, hero_name is bound to a str singleton, so it can be assigned to Hero.name.

Instead of literal sets, it’s common to use a json parameter for bulk inserts. This value is then “unpacked” into a set of json elements and used inside the for loop:

db> 
... 
... 
... 
...

with
  raw_data := <json>$data,
for item in json_array_unpack(raw_data) union (
  insert Hero { name := <str>item['name'] }
);

Parameter <json>$data: [{"name":"Sersi"},{"name":"Ikaris"},{"name":"Thena"}]
{
  default::Hero {id: d7d7e0f6-40ae-11ec-87b1-3f06bed494b9},
  default::Hero {id: d7d7f870-40ae-11ec-87b1-f712a4efc3a5},
  default::Hero {id: d7d7f8c0-40ae-11ec-87b1-6b8685d56610}
}

A similar approach can be used for bulk updates.

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