I have tried different ways to send data in arrays but it shows null. I am sure this is because the response fires before the actual response return. Well, this is my guess! I may be wrong.. I want to know the best practice to do this?
My expected result in the payload:
data: {
allCountries: [{TotalCountries: 12}]
allStates: [{StateId: "15327", STR: "Form",…}, {StateId: "15326", STR: "Form",…},…]
AllCities: [,…]
AllCust: {Id: "1825",…}
}
Now, in nodejs controller, I have 4 functions
exports.getAllDetails = async (req, res) => {
if (!req.query.clientId) {
return res.status(406).send({
success: false,
message: "ID is required"
})
}
let id = req.query['custId'];
let allCountries= await getAllCountries(req, res, id)
// let allStates= this.getStates(req, res, id);
// let allCities= this.getAllCities(req, res, id);
// let custDetails= this.getCustDetails(req, res, id);
return res.send({
success: true,
data:
[allCountries]
[allStates],
[AllCities],
[AllCust]
})
}
Now I have created separate functions for all. i.e.
async function getAllCountries(req, res, id) {
let allCountries;
allCountries= `SELECT query..`
connection.query(allCountries, (err, result) => {
if (result) {
if (result.length > 0) {
return result;
} else {
res.status(204).send({
success: false,
message: `No data found.`,
});
}
}
});
}
I am getting null array in result? Can anyone tell me the best way to do this?
Because you're trying to return data from callback function :
async function getAllCountries(req, res, id) {
let allCountries;
allCountries= `SELECT query..`
connection.query(allCountries, (err, result) => {
if (result) {
if (result.length > 0) {
return result; // this won't work because it is inside callback function.
} else {
res.status(204).send({
success: false,
message: `No data found.`,
});
}
}
});
}
you need to return promise object :
async function getAllCountries(id) {
let allCountries;
allCountries= `SELECT query..`
return new Promise((resolve) => {
connection.query(allCountries, (err, result) => {
if (result) {
if (result.length > 0) {
resolve(result);
} else {
resolve(null);
}
}
});
});
}
also where you're using this function :
let allCountries= await getAllCountries(id);
if (allCountries == null) {
return res.status(204).send({
success: false,
message: `No data found.`,
});
}
I Will recommend you start using try/catch to handle errors instead of all your function passing the param req/res, whit this solution your code will be more readable.
function getAllCountries(req, res, id) {
return new Promise((res, rej) => {
let allCountries;
allCountries = `SELECT query..`;
connection.query(allCountries, (err, result) => {
if (err) {
rej(err);
}
if (result.length === 0) {
rej({
success: false,
message: `No data found.`,
});
}
res(result);
});
});
}
in your main function:
exports.getAllDetails = async (req, res) => {
if (!req.query.clientId) {
return res.status(406).send({
success: false,
message: 'ID is required',
});
}
try {
let id = req.query['custId'];
let allCountries= await getAllCountries(id)
...
return res.send({
success: true,
data: {
allCountries, //as you want this as array wrap the allCountries as [allCountries]
...
}
})
} catch (err) {
return res.status(400).send(err);
}
};