Does mysql query return a promise?

Is query a Promise?

Queries are not promises

They have a . then() function for co and async/await as a convenience. If you need a fully-fledged promise, use the . exec() function.

Can a Promise return a Promise?

We can apply not only normal functions to a Promise but also functions that itself return a Promise . A Promise is a specific implementation of a monad, then is bind / chain and a function that returns a Promise is a monadic function.

How do you handle a Promise return?

load must return a Promise or thenable . The first call will initiate the async methods. Further calls need to return a Promise which can only resolve or reject AFTER the initial Promise has completed. Chaining the promises will only work if no values are passed to the success handler (The first .

Does query return a promise?

The query() method takes an SQL string and an optional array of parameters that will be passed to the query. It returns a Promise object.

Is Mongoose query a promise?

Mongoose queries are not promises. They have a . then() function for co and async/await as a convenience. However, unlike promises, calling a query’s .

Do you need to await promise all?

There is no await all in JavaScript. That’s where Promises. … The main point is that Promise. all() turns an array of promises into a single promise that, if things work, resolves into the array you want.

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Why are promises better than callbacks?

How would you answere these questions in an interview? The superiority of promises over callbacks is all about trust and control. Let me explain. We generally need to use callbacks (or promises) when there is a slow process (that’s usually IO-related) that we need to perform without blocking the main program process.

What is a promise in the Bible?

In the New Covenant scriptures, promise (epangelia) is used in the sense of God’s design to visit his people redemptively in the person of his son Jesus Christ. W. E. Vine says that a promise is “a gift graciously bestowed, not a pledge secured by negotiation.”

How is a promise enforceable?

Thus, a promise may be enforceable to the extent that the promisee has incurred substantial costs, or conferred benefits, in reasonable reliance on the promise. Promissory estoppel under Section 90 of the Restatement of Contracts is the primary enforcement mechanism when action in reliance follows the promise.

Does async return a promise?

Async functions always return a promise. If the return value of an async function is not explicitly a promise, it will be implicitly wrapped in a promise. Note: Even though the return value of an async function behaves as if it’s wrapped in a Promise.resolve , they are not equivalent.

What is difference between promise and async await?

Promise is an object representing intermediate state of operation which is guaranteed to complete its execution at some point in future. Async/Await is a syntactic sugar for promises, a wrapper making the code execute more synchronously. 2. Promise has 3 states – resolved, rejected and pending.

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What happens when a promise is rejected?

If the Promise rejects, the second function in your first . then() will get called with the rejected value, and whatever value it returns will become a new resolved Promise which passes into the first function of your second then. Catch is never called here either.

How do I get my promise value?

Promises are theoretically their own objects. they contain a result which can be accessed through the success function of the promise. So if you want to work with the return value of a promise’s asynchronous callback, it has to be done inside another asynchronous callback.

How do you fix a promise outside?

just take the reference of the function outside and call it. Since functions are object(which are stored as reference in variables) we can call resolve function from outside after taking its reference outside.