Add example project using TypeORM

[amotl]

About

Verify TypeORM works well with CrateDB.

Details

The code has been scaffolded like this:

npx typeorm init --name . --database postgres --express

References

This example uses that other dialect patch needed to make TypeORM compatible with CrateDB.

• CrateDB: Hello, World! crate-workbench/typeorm#1

/cc @proddata, @hammerhead, @hlcianfagna

[amotl]

Problem

The web server does not start, otherwise Express server has started on port 3000 would have been displayed on stdout. It feels like the program just freezes before being able to conclude any significant work.

sink:javascript-typeorm amo$ npm start

> .@0.0.1 start
> ts-node src/index.ts

query: SELECT * FROM current_schema()
query: SELECT version();

Do you have any other idea what could go wrong here? In the CrateDB logs, there is zero indication about any error, effectively no message at all.

[amotl]

Thoughts

CrateDB will respond with a version string like that:

CrateDB 5.2.2 (built a33862e/2023-02-09T10:26:09Z, Linux 5.10.124-linuxkit amd64, OpenJDK 64-Bit Server VM 19.0.2+7)

Not all applications/dialects/drivers like that, because they expect it to be compatible with PostgreSQL, and run feature discovery procedures on it. Does this trip TypeORM as well?

In Python lands, in order to make psycopg and asyncpg compatible with the CrateDB SQLAlchemy dialect, this was one of the details needed to be made compatible.

-- https://github.com/daq-tools/sqlalchemy-postgresql-relaxed/blob/main/sqlalchemy_postgresql_relaxed/base.py#L7-L22
-- crate/crate-python#532

[amotl]

With crate-workbench/typeorm@fcd3841918, the example program advances to a type error, which is natural.

driverError: error: Cannot find data type: serial

[amotl]

With ce929ef, which adjusts the @PrimaryGeneratedColumn to use the UUID strategy, this SQL DDL is generated.

CREATE TABLE "user" (
  "id" uuid NOT NULL DEFAULT uuid_generate_v4(),
  "firstName" character varying NOT NULL,
  "lastName" character varying NOT NULL,
  "age" integer NOT NULL,
  CONSTRAINT "PK_cace4a159ff9f2512dd42373760"
  PRIMARY KEY ("id")
)

PostgresConnectionOptions says:

/**
 * The Postgres extension to use to generate UUID columns. Defaults to uuid-ossp.
 * If pgcrypto is selected, TypeORM will use the gen_random_uuid() function from this extension.
 * If uuid-ossp is selected, TypeORM will use the uuid_generate_v4() function from this extension.
 */
readonly uuidExtension?: "pgcrypto" | "uuid-ossp"

• Reference: Add a uuid type crate#11032
• CrateDB only has gen_random_text_uuid()

[amotl]

To improve the situation, crate-workbench/typeorm#1 uses a dialect for CrateDB to provide CrateDB's gen_random_text_uuid() function as an uuidGenerator to TypeORM.

[amotl]

Within the SQL DDL statement above, the careful reader already spotted that the NOT NULL constraint precedes the DEFAULT clause, and wondered if that would work with CrateDB.

It turns out, it does not.

• PostgreSQL compatibility: DDL statement 'DEFAULT' vs. 'NOT NULL' order variants crate#15156

Now that the dialect does the right thing on the DEFAULT definition, ...

CREATE TABLE "user" ("id" uuid NOT NULL DEFAULT gen_random_text_uuid() ...

... it would be so sweet if CrateDB could be supportive on that end.

[amotl]

There is a patch for CrateDB already. Thanks, @seut.

• Treat column's generated or default expressions as column constraints crate#15159

[hlcianfagna]

In case the output of version() were still an issue, please note that since 5.1.1 it is possible to do the following:

cr> set search_path='public,pg_catalog';
SET OK, 0 rows affected  (0.006 sec)
cr> show search_path;
+--------------------+
| setting            |
+--------------------+
| public, pg_catalog |
+--------------------+
SHOW 1 row in set (0.007 sec)
cr> create function public.version()  RETURNS TEXT
    LANGUAGE JAVASCRIPT
    AS $$function version() {return 'test';}$$;
CREATE OK, 1 row affected  (0.057 sec)
cr> select version();
+--------+
| 'test' |
+--------+
| test   |
+--------+
SELECT 1 row in set (0.912 sec)

[amotl]

Thank you. It will also be interesting for https://github.com/daq-tools/sqlalchemy-postgresql-relaxed.

[amotl]

Note to self: It looks like further explorations stalled after @seut improved this detail on CrateDB the other day and @hlcianfagna added another improvement to the dialect implementation.

• Treat column's generated or default expressions as column constraints crate#15159
• Type mapper and sequence fixes crate-workbench/typeorm#2

[amotl]

@hlcianfagna: Thank you very much for supporting this patch by adding further refinements.

• Type mapper and sequence fixes crate-workbench/typeorm#2
• TypeORM: ID column to string to support UUID #442

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