CODEWITHSUNDEEP
node.jstypescriptasync-await
Curious Blueprints
Curious Blueprints

Reputation: 175

Async function not allowing return type of two promise types in typescript

node 14.7.0, npm 6.14.7, typescript 3.7.3.

I have a method that queries a postgres database and, depending on a param, will return the first row it finds or the entire result from the query. Similar to this:

async getRecord(options: {singleRow: boolean}): Promise<QueryResult> | Promise<Record> {
    const result:QueryResult = await postgres.query(...);
    
    if (options && options.singlerow) {
        return result.rows[0];
    }

    return result;
}

However, I receive the following error: The return type of an async function or method must be the global Promise<T> type. I do not receive an error when I remove the | Promise<Record> section, even though the first return (in the if statement) returns a Promise<Record>. What should I do to fix this?

Upvotes: 0

Views: 504

Answers (1)

Catalyst
Catalyst

Reputation: 3227

Return Promise<QueryResult | Record>

async functions need a Promise to box whatever type they return, there's just one top level Promise-type-generic that wraps the return type.

Upvotes: 3

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