Generating code from DB and making that a build step.

[zetashift]

I have a nx-monorepo using type-safe-api and a CdkApp and I'm using https://www.edgedb.com/. This database has 2 commands, one to generate a (type-safe) query builder and the other to generate TS interfaces.

The commands look like this(run from the root of the nx-monorepo):

To generate the query builder

pnpx @edgedb/generate edgeql-js --output-dir ./packages/mycdkproject/edgeql-js 

To generate the interfaces

pnpx @edgedb/generate queries --file ./packages/mycdkproject/data-access/interfaces.ts

What I would like is to add these 2 generate tasks, but also include them in the build step before the cdk-app is compiled(because I use the query builder and interfaces in the Lambda).

Is the best way here to just create a new TypeScript project(where the build step is running those tasks) and make it a dependency of my cdk-app?

[zetashift]

Also another database related question, tho it's more of Lambda question.

I'm using handlerRouter and I was wondering what the best way was to handle the DB client. The server handles connection pooling, but currently I have a static method that instantiates a new db client:

export class DBClient {
  /** Creates a new connection to our EdgeDB server for data access
   *
   * @returns a new client connected to our EdgeDB instance
   */
  public static create(connString: string | undefined = undefined): edgedb.Client {
    const client = edgedb.createClient(connString);
    return client;
  }
}

But I call DBClient.create in several files like foo.ts, which defines all the handlers for Foo and bar.ts , which defines all the handlers for Bar. The handlers then get aggregated by the handlerRouter and put in a single lambda. I can imagine this might cause performance issues down the line because several clients could be created?

[cogwirrel]

Yeah it looks like if you used DBClient.create in multiple places there might be multiple clients hanging around (if the same container is spun up to serve multiple requests). Usually if you only want a single shared client you can use the singleton pattern, eg:

export class DBClient {
  private static client: edgedb.Client | undefined;

  public static get(): edgedb.Client {
    if (!DBClient.client) {
      DBClient.client = edgedb.createClient();
    }
    return DBClient.client;
  }
}

If your connection string changes you may need to consider keeping a singleton client per connection string, in eg a private static clients: { [connString: string]: edgedb.Client };

Hope that helps! :)

[zetashift]

Ah! That is exactly what I was looking for, never thought about just simply making it an if statement lol!

Thank you!

[cogwirrel]

Is the best way here to just create a new TypeScript project(where the build step is running those tasks) and make it a dependency of my cdk-app?

I think that's the best way! If you generate your code into a TypeScriptProject managed by projen and part of the monorepo, it makes it fairly straightforward to add dependencies! Your suggestion is basically how TypeSafeApi works under the hood - where code generation is run as part of the preCompile task for the relevant projects :)

[zetashift]

Sounds good, I guess this is one of the nice things of the monorepo :D