Postgres: Filter Using Values of Computed Fields
Introduction
You can use computed fields to filter your query results.
For example:
query {
author(where: { full_name: { _ilike: "%bob%" } }) {
id
first_name
last_name
}
}
The behavior of the comparison operators depends on whether the computed fields return scalar type values or set of table rows.
- In case of scalar type, a row will be returned if the computed field returned scalar value satisfied the defined condition.
- In case of table row type, a row will be returned if any of the returned rows sastisfy the defined condition.
Let's look at a few use cases based on the above:
Fetch if the scalar value returned by the computed field satisfies a condition
Example:
A computed field total_marks defined to a student table which computes the total sum of marks obtained from each
subject. Fetch all students whose total marks is above "80":
Fetch if any of the returned table rows by the computed field satisfy a condition
Example:
A computed field get_published_articles defined to a author table which returns set of article rows published.
Fetch all authors who have atleast a published article in medicine field:
Fetch if aggregate value of the returned table rows by the computed field satisfies a condition
Example:
A computed field get_published_articles defined to a author table which returns set of article rows published.
Fetch all authors whose count of published articles is more than 10:
