Add key on each json object in Promise - node.js

Question

I have the following Promise and Promise.all which works and it returns a json object. However, I want to add a key for each return object.
as of now, it returns something
[value: {school object}, value:{students object}, value:{classroom object}]
desired output:
["schools": {school object }, {students object} , {classroom object} ]
Current Implementation:
new Promise((resolve, reject) => {
const school = getschool (webHost, dataSource, req);
const classRooms = getClassRooms(webHost, dataSource, req);
const students = getstudents (webHost,dataSource, req);
Promise.all([school ,classRooms,students ]).then((res) => {
resolve(res);
})
.catch((error) => {
logger.error(`${error}`);
reject(error);
});
});
classroom
{
"metadata": "metadata",
"value": [
{
"class_id": "171717",
"teacher_name": "Science"
}
]
}
School object
{
"metadata": "metadata",
"value": [
{
"id": "2345354",
"schoolName": "Memorial High School"
}
]
}
Student json
{
"metadata": "metadata",
"value": [
{
"id": "1234",
"studentName": "Beck"
},
{
"id": "5678",
"studentName": "Jeck"
}
]
}
Desired Output:
[
{
"class_id":"171717",
"teacher_name":"Science",
"id":"2345354",
"schoolName":"Memorial High School",
"Students":[
{
"id":"1234",
"studentName":"Beck"
},
{
"id":"5678",
"studentName":"Jeck"
}
]
}
]

Answer 1

It seems like you want to merge the objects to make one unified object of custom type, here is what you want to do:
res => resolve(
{
...res[1].value[0],
...res[0].value[0],
Students: res[2].value
}
)
The ... is called spread syntax. It "explodes" the objects and arrays. What we want here is get the internals of classRooms.value[0] merge them with school.value[0] object's internals, and then, add another attribute at the same level with key as Students which is a not-exploded array specified by student.value.
Here I have created a small TS Playground Example for you to play with the syntax and modify the output the way you may seem fit.
If you run it, it prints the desired output:
{
"class_id": "171717",
"teacher_name": "Science",
"id": "2345354",
"schoolName": "Memorial High School",
"Students": [
{
"id": "1234",
"studentName": "Beck"
},
{
"id": "5678",
"studentName": "Jeck"
}
]
}
-- ORIGINAL ANSWER --
Promise.all returns a promise of resolved objects in an array. So, the .then takes the parameter that's an array of resolved objects in the same order. That means your res parameter is an array of school object, students object, and classroom object in that order. you can do the following to "zip" them up.
new Promise((resolve, reject) => {
const school = getschool (webHost, dataSource, req);
const classRooms = getClassRooms(webHost, dataSource, req);
const students = getstudents (webHost,dataSource, req);
Promise.all([school ,classRooms,students ]).then((res) => {
resolve({"schools": res[0], "classRooms" : res[1], "students": res[2]});
})
.catch((error) => {
logger.error(`${error}`);
reject(error);
});
});
or even better,
.then(([schools, classRooms, students]) => {
resolve({schools, classRooms, students});
})