Change primary key and its (foreign) references in existing table - Knex.js / Postgres - postgresql

Question

My Postgres DB has 2 tables, with thousands of rows each, that were initially created with the following migration:
exports.up = async function(knex, Promise) {
// users
await knex.schema.createTable('users', table => {
table.increments('id');
table.timestamps(false, true);
table.text('uid').notNullable().unique(),
table.text('email').notNullable();
table.text('password');
table.text('first_name').notNullable();
table.text('last_name').notNullable();
table.text('subscription_id');
table.boolean('is_active').notNullable().defaultTo(true);
table.boolean('is_blocked').notNullable().defaultTo(false);
table.enum('role', ['member', 'admin', 'test_user']).notNullable().defaultTo('member');
});
await knex.schema.raw('create unique index users_lower_email_index on users (lower(email))');
// projects
await knex.schema.createTable('projects', table => {
table.increments('id');
table.timestamps(false, true);
table.text('name').notNullable();
table.integer('user_id').notNullable().references('users.id').onDelete('cascade');
table.text('data');
});
};
I need to change the foreign key on the projects table so that it references the uid column instead from the users table.
The constraints on the users table are:
I tried the following migration but I get the error:
migration failed with error: alter table "users" add column "uid" text - column "uid" of relation "users" already exists
My code:
exports.up = async function(knex, Promise) {
await knex.schema.alterTable('users', table => {
table.text('uid').primary('users_pkey');
})
await knex.schema.alterTable('projects', table => {
table.text('user_id').notNullable().references('users.uid').onDelete('cascade').alter();
});
};
I also tried table.text('uid').primary('users_pkey').alter(); but then I get:
migration failed with error: alter table "users" add constraint "users_pkey" primary key ("uid") - multiple primary keys for table "users" are not allowed
I will transfer all users in auth0 and I though its better if I use a UUID primary key for the users table.

Answer 1

Before you can change the primary key of users, you need to remove the existing one, then you should be able to drop and recreate the foreign key in projects:
exports.up = async (knex) => {
await knex.schema.alterTable('users', (table) => {
table.dropPrimary()
table.primary('uid')
})
await knex.schema.alterTable('projects', (table) => {
table.dropForeign('user_id')
table.foreign('user_id').references('users.uid').onDelete('cascade')
})
}