postgraphile-index-to-unique-constraint-plugin

Convert unique index to fake unique constraint

Motivation

Postgraphile generate field for unique constraint on a table using a PgRowByUniqueConstraint.

However this only works for each unique constraints, not unique index. To resolve this issue, one could have created a PgRowByUniqueIndex plugin, but this creates a lot of redundant code. And because the unique index behave exactly like unique constraint. So I think it would work well to inject a plugin in the build phase, (not init phase) to create "fake" constraint from unique index.

Since I am already making fake unique constraints, I also added a plugin called uniqueConstraintFromSmartComment. Which create fake unique constraint based on the smart comment on views. if you add a smart comment on view (only view, not table, not materialized view), it will be unique constraint.

  comment on view xxx is E'@unique (column1,column2)';

These will be added as a fake unique constraint. The reason I do this is because postgres does not support unique constraint on views, (only on table/mat view). So If you are sure a view's column (or multiple) is unique, you can use create this unique constraint.

Usage

npm install postgraphile-index-to-unique-constraint-plugin

Then add it to the postgraphile plugins import { addFakeUniqueConstraintFromIndex } from 'postgraphile-polymorphic-relation-plugin';

createPostGraphileSchema(client, ['p'], {
        appendPlugins: [
          addFakeUniqueConstraintFromIndex,
        ],
      });