Experiments with a tiny DB wrapper

BaseTable.ts

// abstract: don't allow direct instantiation
abstract class BaseTable<T> {
    // model holds the schema
    protected model: T;
    
    // convert kebab_case to camelCase
    private camelCase(key: string) {
        return key.replace(/_(\w)/g, function (...captures: string[]) {
            return captures[1].toUpperCase();
        });
    }

    // convert camelCase to kebab_case (naïve impl)
    private kebabCase(key: string) {
        let kebabKey = '';

        for (let i = 0; i < key.length; i++) {
            if (key[i] === key[i].toLowerCase()) {
                kebabKey += key[i];
            }
            else {
                kebabKey += '_' + key[i].toLowerCase();
            }
        }

        return kebabKey;
    }

    constructor(model?: T) {
        if (model) {
            this.model = model;
        }
    }

    // init table from a database object
    initFromDb(model: any) {
        if (this.model) {
            throw new Error('Model already constructed via constructor!');
        }

        const newModel = {} as T;

        for (let key in model) {
            // convert snake_cased db field to camelCase
            const camelKey = this.camelCase(key);
            Object.assign(newModel, { [camelKey]: model[key] });
        }

        this.model = newModel;
    }

    // serialise to kebab_cased db object
    toDbObject() {
        const dbObj = {};
        const model = this.model;

        for (let key in model) {
            const kebabKey = this.kebabCase(key);

            Object.assign(dbObj, { [kebabKey]: model[key] });
        }

        return dbObj;
    }

    // serialise to camelCased JSON
    toString() {
        return JSON.stringify(this.model);
    }
}

Table.ts

interface Model {
    id: number;
    postId: number;
    parentName: string;
}

class Table extends BaseTable<Model> {
    show() {
        return this.model.postId + ': ' + this.model.parentName;
    }
}

test.ts

let table = new Table({
    id: 99,
    postId: 77,
    parentName: 'the parent'
});

console.log(table.toDbObject());
console.log(table.toString());
console.log(table.show());

table = new Table();
table.initFromDb({
    id: 99,
    post_id: 77,
    parent_name: 'the parent'
});

console.log(table.toDbObject());
console.log(table.toString());
console.log(table.show());