Assign an object to a Map, where the Map is defined using type parameters from the parent class
When working with TypeScript, you may come across situations where you need to assign an object to a Map, where the Map is defined using type parameters from the parent class. In this blog post, we will explore different solutions to this problem.
Solution 1: Using a type assertion
One way to assign an object to a Map with type parameters from the parent class is by using a type assertion. This allows you to tell the TypeScript compiler that you know the object conforms to the desired type.
class ParentClass {
map: Map = new Map();
}
class ChildClass extends ParentClass {
constructor() {
super();
this.map.set('key1', 1);
this.map.set('key2', 2);
}
}
const child = new ChildClass();
const objectToAssign = {
key3: 3,
key4: 4,
};
// Type assertion
child.map = objectToAssign as Map;
In the above code snippet, we define a ParentClass with a generic type parameter T. The ChildClass extends the ParentClass and assigns values to the map property. We then create an objectToAssign with additional key-value pairs. Finally, we use a type assertion to assign the objectToAssign to the child.map property.
Solution 2: Using a custom function
Another approach is to create a custom function that iterates over the object’s key-value pairs and assigns them to the Map.
class ParentClass {
map: Map = new Map();
}
class ChildClass extends ParentClass {
constructor() {
super();
this.map.set('key1', 1);
this.map.set('key2', 2);
}
}
const child = new ChildClass();
const objectToAssign = {
key3: 3,
key4: 4,
};
function assignObjectToMap(map: Map, object: { [key: string]: T }) {
for (const key in object) {
if (object.hasOwnProperty(key)) {
map.set(key, object[key]);
}
}
}
assignObjectToMap(child.map, objectToAssign);
In this solution, we define a custom function assignObjectToMap that takes a Map and an object as arguments. The function iterates over the object’s key-value pairs using a for…in loop and assigns them to the Map using the set method.
These are two possible solutions to assign an object to a Map, where the Map is defined using type parameters from the parent class. Choose the solution that best fits your specific use case and coding style.
Feel free to experiment with these solutions and adapt them to your own projects. Happy coding!
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