Is there a way to extract a specific property of a combined type and generate a new type from it?
Consider the following example:
type Actions =
| {
type: "ADD_COLUMN";
newColumnIndex: number;
column: SelectorColumnData;
}
| {
type: "ITEM_CHECKED";
columnIndex: number;
item: SelectorItem;
};
Is there a clever generic solution that we can utilize to create something like this:
type ActionTypes = GetTypes<Actions>
// ActionTypes = "ADD_COLUMN" | "ITEM_CHECKED"
To retrieve all potential values of a key from the combination of objects, you simply need to access a property from the specific type. This process can be achieved by:
Action["type"];
If your intention is to actually define a type, you must utilize "extends" as well. This allows TypeScript to safely enable property access.
type Actions =
| {
type: "ADD_COLUMN";
newColumnIndex: number;
column: string;
}
| {
type: "ITEM_CHECKED";
columnIndex: number;
item: string;
};
type GetTypes<T extends { type : string }> = T['type'];
type ActionTypes = GetTypes<Actions>
After a thorough search, I managed to discover the solution in a different location. Surprisingly, it doesn't involve the use of generics:
const ActionTypes = Actions["type"];
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