Allow for Better Inheritance and Extendability of Generated Entity Models

[filo87]

It would be great to be able to extend the definitions of generated models (from yarn codegen) and instantiate sub-classes with enhanced functionalities and logic by still maintaining the methods of the original parent Entity (like save(), get(), ...).

As an example, given a generated model Entity Account it should be possible to do something like this:

// this is the model generated from yarn codegen
class Account implements Entity {
...
}

// this is a child class extending Account somewhere else in the code
class AccountService extends Account {

async doStuff() {
      const service = await this.get('xyz') // <- Should return an instance of AccountService and NOT of Account
   }
}

for this purpose, all static methods returning an instance of the model Entity class should call the constructor and their own static methods as this and NOT as className.

here some examples:

subql/packages/cli/src/template/model.ts.ejs

Line 42 in b0f0bbc

return <%=props.className %>.create(record as <%= props.className %>Props);

subql/packages/cli/src/template/model.ts.ejs

Line 66 in b0f0bbc

let entity = new <%=props.className %>(record.id);

[jamesbayly]

Interesting idea, our models are autogenerated so we would need to make sure that we don't overwrite the extended definitions

[stwiname]

@filo87, it seems like you have a good understanding of this problem. If you would like to make a PR we would happily add the feature.

[filo87]

Ok great will prepare a PR for this

[filo87]

@stwiname Here the PR: #1377

Not much to change, only in the ejs model template:

• The .create() static method should use this as reference so that when called from a child class it returns an instance of the child (with all methods in the prototype).
• All getters should also be adapted to call the this.create() method
• The entityProps type should be exported so it can be used in the child classes when using the .create() method

this should already do the job!

I quickly tried the template in my project and was OK...what additional testing is required?

[jiqiang90]

Close this now, pr merged