postgraphile-plugin-foreign-field-direction

This plugin allows you to expose only a single direction of connections exposed by foreign key
constraints.

Example

With the following schema

``sql
create table classroom (
id int primary key
);
create table teacher (
id int primary key,
classroom_id int not null references classroom(id)
);
`

in the GraphQL generated, the Teacher type will have a classroomByClassroomId field, and the
Classroom type will have a teachersByClassroomId field.

By using the foreignFieldDirection smart tag, you can choose to expose only one of those two
fields.

For example, via a smart comment

`sql
comment on constraint teacher_classroom_id_fkey on teacher is E'@foreignFieldDirection forward';
`

Primary Key as Foreign Key Example

With the following schema

`sql
create table classroom (
id int primary key
);
create table classroom_other_info (
id int primary key references classroom(id)
);
`

in the GraphQL generated, the Classroom type will have a classroomOtherInfoById field and a
classroomOtherInfosById field. Setting the foreign field direction to forward only will omit both
these fields on Classroom.

Usage

This is a simple plugin. You can just copy it into your project and modify as needed. You can
install it using npm or yarn:

`sh
yarn add postgraphile-plugin-foreign-field-direction
`

`js
const { ForeignFieldDirectionPlugin } = require('postgraphile-plugin-foreign-field-direction')
`

Smart Tag Arguments

forward and backward are the only valid arguments for the foreignFieldDirection smart tag.
Any other value, including a blank value, will set throw an error and prevent the GQL schema from
compiling.

The forward argument indicates that you want to expose a traversal only FROM the table on which
the constraint is defined.

The backward` argument indicates that you want to expose a traversal only TO the table on which
the constraint is defined.

Compatibility

This plugin has no dependencies. It was tested with Postgraphile v4.12.9.