How to get a type alias from a class?

[shyakadavis]

Hi.

Say I wanted to infer/retrieve a type alias from my class; how would I achieve that?

Context:

This is my class:

import {
	prop,
	getModelForClass,
	post,
	ModelOptions,
	Severity,
} from '@typegoose/typegoose';
import mongoose from 'mongoose';

@post<LoanClass>('save', function (doc) {
	if (doc) {
		doc.id = doc._id.toString();
		doc._id = doc.id;
	}
})
@post<LoanClass[]>(/^find/, function (docs) {
	// @ts-ignore
	if (this.op === 'find') {
		docs.forEach((doc) => {
			doc.id = doc._id.toString();
			doc._id = doc.id;
		});
	}
})
@ModelOptions({
	schemaOptions: {
		timestamps: true,
		collection: 'loans',
	},
	options: {
		allowMixed: Severity.ALLOW,
	},
})
class LoanClass {
	@prop({ required: true })
	lenderAddress: string;

	@prop({ required: true })
	loanToken: string;

	@prop({ required: true })
	loanAmount: string;

	@prop({ required: true })
	collateralToken: string;

	@prop({ required: true })
	collateralAmount: string;

	@prop({ required: true })
	liquidationThreshold: string;

	@prop({ required: true })
	initialThreshold: string;

	@prop({ required: true })
	loanRepayDeadline: Date;

	@prop({ required: true })
	loanRequestDeadline: Date;

	@prop({ required: true })
	interestRate: string;

	@prop({ required: true })
	managerNFT: string;

	@prop({ default: 'v1' })
	managerNFTVersion: string;

	_id: mongoose.Types.ObjectId | string;

	id: string;
}

const Loan = getModelForClass(LoanClass);
export { Loan, LoanClass };

And I want to be able to use the inferred type alias when populating an array like so:

let some_array: TLoan[]; // how can I get the type alias for this

some_array = [
{
	collateralAmount: '',
	collateralToken: '',
	loanAmount: '',
	loanToken: '',
	loanRepayDeadline: new Date(),
	initialThreshold: '',
	interestRate: '',
	liquidationThreshold: '',
	lenderAddress: '',
	loanRequestDeadline: new Date(),
	managerNFT: '',
	managerNFTVersion: '',
}
];

---

While I have you, do you mind having a look at that class definition, and telling me if I'm doing something the wrong way. I'm new to Typgoose, and navigating the docs is kinda hard. For example, understanding the public prefix is something that escapes me and its importance/significance thereof.

Thanks for the consideration.

[hasezoey]

Say I wanted to infer/retrieve a type alias from my class; how would I achieve that?

i am not quite sure what you mean with "type alias", but if you are referring to having a type of the class that does not include functions, then maybe look at FilterOutFunctionKeys, otherwise please provide more specifics on what that type should be

[shyakadavis]

Hi, @hasezoey

Thanks for the reply.

And yes, that was exactly what I wanted. i.e. FilterOutFunctionKeys.

Basically, what I wanted was just a way to type my function params, and different arrays but adhering to the class's shape.

Thanks a lot. 🙂

Also, if it's no bother, do you mind having a look at that class definition. From first glance, does it look like I'm doing something wrong? For example, I see from the docs you use the public prefix; what does that do specifically, in terms of Typegoose, at least?

[hasezoey]

Also, if it's no bother, do you mind having a look at that class definition. From first glance, does it look like I'm doing something wrong?

the only thing from the provided class i see that could be wrong is allowMixed: Severity.ALLOW,, it is not great to disable Mixed warnings for everything, if you have a property that is gonna be mixed and it is not accidental, then the prop option should be used instead @prop({ allowMixed: Severity.CHOOSE })

For example, I see from the docs you use the public prefix; what does that do specifically, in terms of Typegoose, at least?

please read typescript Member Visibility
as for why typegoose chooses this way even if not necessary, is because we (i) have gone for that style choice (for tests and documentation)
TL;DR: public along with protected and private are typescript member visibility (like in java, C# and other languages), and members are public by default - those things do not exist at runtime so they dont affect typegoose (they do affect the typescript types though) (and private is completely separate from ES private fields starting with #, which are unsupported by typegoose)