18: FOR loops

Another way to work with the items inside an array is to use a FOR loop. After FOR, choose a parameter name (like $item or $person) to be used every time the loop occurs, follow it with IN and the data, and then {} to open up a space in which you can write custom logic for each item in the loop.

Inside the loop in the next query, the parameter $person can be used to set the fields of each person record. Since each step of a FOR loop is isolated inside its own space, the output of a FOR loop will always be empty. To see the results of the person records created in this way, we will need to use a SELECT statement after the loop is done.

FOR $person IN [
  {
    age: 30,
    name: 'Sara Bellum'
  },
  {
    age: 25,
    name: 'Lydia Wyndham'
  },
  {
    age: 45,
    name: 'Samm Schwartz'
  }
] {
    CREATE person SET
      age = $person.age,
      name = $person.name
};

SELECT * FROM person;

Run Query

[
  {
    age: 45,
    id: person:cj8wc617o1ea2vs1yv4n,
    name: 'Samm Schwartz'
  },
  {
    age: 30,
    id: person:e8z6pjqhuwzfalbku61n,
    name: 'Sara Bellum'
  },
  {
    age: 25,
    id: person:faovorn8ntkqwfw01638,
    name: 'Lydia Wyndham'
  }
]

This is the way that we will create these employees for the library, but we also want to link each one to the library at each step of the FOR loop after creating them (so run a quick DELETE person at this point if you are following along separately). This time the link will be something called a graph edge, which we will first need to learn to use starting on the next page.