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In node.js I need to use a function procesMultipleCandidates () which contains Array.foreach which process insert every element into db. but the entire function should return response after completing all insertion operation
JavaScript Code
async function procesMultipleCandidates (data) {
let generatedResponse = []
await data.forEach(async (elem) => {
try {
// here candidate data is inserted into
let insertResponse = await insertionInCandidate(elem)
//and response need to be added into final response array
generatedResponse.push(insertResponse)
} catch (error) {
console.log('error'+ error);
}
})
console.log('complete all') // gets loged first
return generatedResponse // return without waiting for process of
}
And as described above last return statement not waiting for the foreach execution to complete first.
254
forEach is not designed for asynchronous code. (It was not suitable for promises, and it is not suitable for async-await.)
The Solution It turns out that the array. forEach method only accepts a synchronous function, and therefore is NOT compatible with the async/await syntax. Instead, you can use the for … of iterator as per below which is compatible with the async/await syntax.
forEach() expects a synchronous function — it does not wait for promises. Make sure you are aware of the implications while using promises (or async functions) as forEach callbacks.
When evaluate for loop, we have await promise inside the async function, the execution will pause until the await promise is settled. So, you can think of that the files are read one by one in a determined order. Sometimes, we really need the the async functions to be executed in a sequential order.
Use Array.prototype.map and Promise.all:
async function procesMultipleCandidates (data) {
let generatedResponse = []
await Promise.all(data.map(async (elem) => {
try {
// here candidate data is inserted into
let insertResponse = await insertionInCandidate(elem)
// and response need to be added into final response array
generatedResponse.push(insertResponse)
} catch (error) {
console.log('error'+ error);
}
}))
console.log('complete all') // gets loged first
return generatedResponse // return without waiting for process of
}
Or use a for/of loop if you don't want the loop run concurrently:
async function procesMultipleCandidates (data) {
let generatedResponse = []
for(let elem of data) {
try {
// here candidate data is inserted into
let insertResponse = await insertionInCandidate(elem)
// and response need to be added into final response array
generatedResponse.push(insertResponse)
} catch (error) {
console.log('error'+ error);
}
}
console.log('complete all') // gets loged first
return generatedResponse // return without waiting for process of
}
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