question is possibly a duplicate but I haven't found anything that provides an appropriate answer to my issue.
I have an ExpressJS server which is used to provide API requests to retrieve data from a MongoDB database. I am using mongoosejs for the MongoDB connection to query/save data.
I am building a route that will allow me to find all data that matches some user input but I am having trouble when doing the query. I have spent a long while looking online for someone with a similar issue but coming up blank.
I will leave example of the code I have at the minute below.
code for route
// -- return matched data (GET)
router.get('/match', async (req, res) => {
const style_data = req.query.style; // grab url param for style scores ** this comes in as a string **
const character_data = req.query.character; // grab url param for character scores ** this comes in as a string **
// run matcher systems
const style_matches = style_match(style_data);
res.send({
response: 200,
data: style_matches
}); // return data
});
code for the query
// ---(Build the finder)
const fetch_matches_using = async function(body, richness, smoke, sweetness) {
return await WhiskyModel.find({
'attributes.body': body,
'attributes.richness': richness,
'attributes.smoke': smoke,
'attributes.sweetness': sweetness
});
}
// ---(Start match function)---
const style_match = async function (scores_as_string) {
// ---(extract data)---
const body = scores_as_string[0];
const richness = scores_as_string[1];
const smoke = scores_as_string[2];
const sweetness = scores_as_string[3];
const matched = [];
// ---(initialise variables)---
let match_count = matched.length;
let first_run; // -> exact matches
let second_run; // -> +- 1
let third_run; // -> +- 2
let fourth_run; // -> +- 3
// ---(begin db find loop)---
first_run = fetch_matches_using(body, richness, smoke, sweetness).then((result) => {return result});
matched.push(first_run);
// ---(return final data)---
return matched
}
example of db object
{
_id: mongoid,
meta-data: {
pagemd:{some data},
name: whiskyname
age: whiskyage,
price: price
},
attributes: {
body: "3",
richness: "3",
smoke: "0",
sweetness: "3",
some other data ...
}
}
When I hit the route in postman the JSON data looks like:
{
response: 200,
data: {}
}
and when I console.log() out matched from within the style match function after I have pushed the it prints [ Promise(pending) ] which I don't understand.
if I console.log() the result from within the .then() I get an empty array.
I have tried using the populate() method after running the find which does technically work, but instead of only returning data that matches it returns every entry in the collection so I think I am doing something wrong there, but I also don't see why I would need to use the .populate() function to access the nested object.
Am I doing something totally wrong here?
I should also mention that the route and the matching functions are in different files just to try and keep things simple.
Thanks for any answers.
just posting an answer as I seem to have fixed this.
Issue was with my .find() function, needed to pass in the items to search by and then also a call back within the function to return error/data. I'll leave the changed code below.
new function
const fetch_matches_using = async function(body, richness, smoke, sweetness) {
const data = await WhiskyModel.find({
'attributes.body': body,
'attributes.richness': richness,
'attributes.smoke': smoke,
'attributes.sweetness': sweetness
}, (error, data) => { // new ¬
if (error) {
return error;
}
if (data) {
console.log(data)
return data
}
});
return data; //new
}
There is still an issue with sending the found results back to the route but this is a different issue I believe. If its connected I'll edit this answer with the fix for that.
Related
I receive JSON data from the service, but the keys change in the data with each request, below I will give an example in three versions.
Exmaple 1:
{
"trackingPayloads": {
"Rltyn4gLRIWRKj9kS0YpWXytG81GZwcPWjEE7f31ALlq": "{"title":"Red Shoes","index":3,"id":"17777","type":"category"}',
"ywtA6OyM0hzVZZvnUjxoxJDI1Er9ArfNr8XKyi1D5Zzk": "{"title":"White Shoes","index":3,"id":"17777","type":"category"}',
}
}
Example 2:
{
"trackingPayloads": {
"36tW7DqZ3H9KKBEAumZmowmUwmDRmVCjQgv5zi9GM3Kz": "{"title":"Red Shoes","index":3,"id":"17777","type":"category"}',
"OgtE51n3YtvrVXWLFjPmpnRt2k5DExF7ovxmBTZrZ6wV": "{"title":"White Shoes","index":3,"id":"17777","type":"category"}',
}
}
Example 3:
{
"trackingPayloads": {
"k2toY29glt2JEp9Wi1X5M7ocno0E0mS4JQVyDuGyQ2rM": "{"title":"Red Shoes","index":3,"id":"17777","type":"category"}'",
"5ef2ec3c3573eebecc9690b69619ec7b9c93b609": "{"title":"White Shoes","index":3,"id":"17777","type":"category"}',
}
}
As you can see, the data included in the keys does not change since I am requesting the same information, but the key will change with each request.
Please help, what are the options to get the data Title, Index and any other content in these keys using node js?
Only one option came to my mind - to rename the keys upon receipt in 1,2,3 ... and then get data from them, but this needs to be done dynamically, since about 120 requests per minute are made, you need to get this data quickly, there are no options to save it to a file (I didn’t understand how)
UPDATE, added my code.
I am attaching an example of my code, the idea is to eventually get the data I need from the right keys from trackingPayloads, please help with the code <3
const AwaitAPIResponse = await ProductAPI(product_sku);
const $ = cheerio.load(AwaitAPIResponse);
const JSONDATA = [];
$('pre').each(function() {
JSONDATA.push($(this).text());
});
const ProductJson = JSON.parse(JSONDATA[0]) // this is where I get all the data
const MainJson = ProductJson["trackingPayloads"] // here I go to the trackingPayloads you saw above
How can I get the data I need?
You can use Object.keys() to get all the different keys of an object and use a loop to go through them.
Therefore, you can rework this code in such a way that each of the values is stored as an element in an array, maybe makes the data easier to work with:
const convert = object => {
const ret = []
for (const key of Object.keys(object)) {
ret.push(object[key])
}
return ret
}
This will give you following result for your use case:
[{"title":"Red Shoes","index":3,"id":"17777","type":"category"},
{"title":"Red Shoes","index":3,"id":"17777","type":"category"}]
The way you'd call this is as follows:
const some_parsed_json = {
"k2toY29glt2JEp9Wi1X5M7ocno0E0mS4JQVyDuGyQ2rM": {
title:"Red Shoes",
index:3,
id:"17777",
type:"category"
},
"5ef2ec3c3573eebecc9690b69619ec7b9c93b609": {
title:"Red Shoes",
index:3,
id:"17777",
type:"category"
}
}
const json_object_values = convertor(some_parsed_json)
If you don't car about the key you could use Object.values on the received object to get the values
Object.values(payload)
// With your example it will return:
// [{"title":"Red Shoes","index":3,"id":"17777","type":"category"},
// {"title":"Red Shoes","index":3,"id":"17777","type":"category"}]
or in a more complete example
async function getParsedValues() {
const responseString = await service.getData(); // '{"trackingPayloads":{"Rltyn4gLRIWRKj9kS0YpWXytG81GZwcPWjEE7f31ALlq":{"title":"Red Shoes","index":3,"id":"17777","type":"category"},"ywtA6OyM0hzVZZvnUjxoxJDI1Er9ArfNr8XKyi1D5Zzk":{"title":"White Shoes","index":3,"id":"17777","type":"category"}}}'
const parsedResponse = JSON.parse(responseString); // { trackingPayloads: { Rltyn4gLRIWRKj9kS0YpWXytG81GZwcPWjEE7f31ALlq: { title:'RedShoes', index: 3, id: '17777', type: 'category' }, ywtA6OyM0hzVZZvnUjxoxJDI1Er9ArfNr8XKyi1D5Zzk:{title:'WhiteShoes', index: 3, id: '17777', type: 'category' } }}
const values = Object.values(parsedResponse); // [{"title":"Red Shoes","index":3,"id":"17777","type":"category"}, {title:'WhiteShoes', index: 3, id: '17777', type: 'category' }]
return values;
}
I'm currently working on a NodeJS project, this takes data from a JSON and then use it to take weather stuff form an API, after that I want to save it to a DB, I already asked about it and that question helped me fixing some problems but now I have some others, I'm sending the data to a constant but the issue is that I don't know why am I getting an error in the JSON Parse, I want to use the lat and lon from the JSON (I have like a hundred data coords) and insert it into the const, any help would help, This is the error I'm getting
Successful connection
[]
undefined:1
^
SyntaxError: Unexpected token in JSON at position 0
at JSON.parse (<anonymous>)
here is my function that takes data from JSON and gets data from the API:
async function calcWeather() {
fs.readFile("./json/data.json","utf8", function (err, data) {
if(err) throw err;
data2 = JSON.parse(data);
console.log(typeof data2);
for (let item of data2) {
let base = `https://api.openweathermap.org/data/2.5/weather?lat=${item.latjson}&lon=${item.lonjson}&appid=${api_key}&units=metric&lang=sp`;
fetch(base)
.then((responses) => {
return responses.json();
})
.then((data) => {
var myObject = {
Id_Oficina: item.IdOficina,
Humedad: data.main.humidity,
Nubes: data.clouds.all,
Sensacion: data.main.feels_like,
Temperatura: data.main.temp,
Descripcion: data.weather.description,
};
// validation and saving data to array
if (myObject.Temperatura < 99) {
lstValid.push(myObject);
}
});
}
});
console.log(lstValid);
}
here is the JSON where I take the data:
[
{
"latjson": 1,
"lonjson": 1,
"IdOficina": "1"
},
{
"latjson": 2,
"lonjson": 2,
"IdOficina": "2"
}
]
I think the issue is in the parse, but I don't get what I am doing wrong
Since you are reading the file with fs.readFile, you are getting a string and not a JavaScript object. You would need to parse it entirely in order to be able to manipulate the content (you seem to be parsing the first character only):
const fs = require('fs')
let rawdata = fs.readFileSync('./data.json')
let data = JSON.parse(rawdata)
Personally, I think it's way easier to require it (no need to use fs):
const jsonData = require('./json/data.json')
async function calcWeather() {
for (let item of jsonData) {
// ...
}
}
Via a microservice, I retrieve several packages of JSON data and spit them out onto a Vue.js-driven page. The data looks something like this:
{"data":{"getcompanies":
[
{"id":6,"name":"Arena","address":"12 Baker Street","zip":"15090"},
{"id":7,"name":"McMillan","address":null,"zip":"15090"},
{"id":8,"name":"Ball","address":"342 Farm Road","zip":"15090"}
]
}}
{"data":{"getusers":
[{"id":22,"name":"Fred","address":"Parmesean Street","zip":"15090"},
{"id":24,"name":"George","address":"Loopy Lane","zip":"15090"},
{"id":25,"name":"Lucy","address":"Farm Road","zip":"15090"}]}}
{"data":{"getdevices":
[{"id":2,"name":"device type 1"},
{"id":4,"name":"device type 2"},
{"id":5,"name":"device type 3"}]}}
...and I successfully grab them individually via code like this:
getCompanies() {
this.sendMicroServiceRequest({
method: 'GET',
url: `api/authenticated/function/getcompanies`
})
.then((response) => {
if(response.data) {
this.dataCompanies = response.data.getcompanies
} else {
console.error(response)
}
}).catch(console.error)
}
...with getUsers() and getDevices() looking respectively the same. getCompanies() returns:
[{"id":6,"name":"Arena","address":"12 Baker Street","zip":"15090"},
{"id":7,"name":"McMillan","address":null,"zip":"15090"},
{"id":8,"name":"Ball","address":"342 Farm Road","zip":"15090"}]
...which I relay to the Vue template in a table, and this works just fine and dandy.
But this is obviously going to get unwieldy if I need to add more microservice calls down the road.
What I'm looking for is an elegant way to jump past the response.data.*whatever* and get to those id-records with a re-useable call, but I'm having trouble getting there. response.data[0] doesn't work, and mapping down to the stuff I need either comes back undefined, or in bits of array. And filtering for response.data[0].id to return just the rows with ids keeps coming back undefined.
My last attempt (see below) to access the data does work, but looks like it comes back as individual array elements. I'd rather not - if possible - rebuild an array into a JSON structure. I keep thinking I should be able to just step past the next level regardless of what it's called, and grab whatever is there in one chunk, as if I read response.data.getcompanies directly, but not caring what 'getcompanies' is, or needing to reference it by name:
// the call
this.dataCompanies = this.getFullData('companies')
getFullData(who) {
this.sendMicroServiceRequest({
method: 'GET',
url: 'api/authenticated/function/get' + who,
})
.then((response) => {
if(response) {
// attempt 1 to get chunk below 'getcompanies'
Object.keys(response.data).forEach(function(prop) {
console.log(response.data[prop])
})
// attempt 2
// for (const prop in response.data) {
// console.log(response.data[prop])
// }
let output = response.data[prop] // erroneously thinking this is in one object
return output
} else {
console.error(response)
}
}).catch(console.error)
}
...outputs:
(63) [{…}, {…}, {…}] <-- *there are 63 of these records, I'm just showing the first few...*
0: {"id":6,"name":"Arena","address":"12 Baker Street","zip":"15090"}
1: {"id":7,"name":"McMillan","address":null,"zip":"15090"},
2: {"id":8,"name":"Ball","address":"342 Farm Road","zip":"15090"}...
Oh, and the return above comes back 'undefined' for some reason that eludes me at 3AM. >.<
It's one of those things where I think I am close, but not quite. Any tips, hints, or pokes in the right direction are greatly appreciated.
I feel it's better to be explicit about accessing the object. Seems like the object key is consistent with the name of the microservice function? If so:
getData(functionName) {
return this.sendMicroServiceRequest({
method: 'GET',
url: "api/authenticated/function/" + functionName
})
.then( response => response.data[functionName] )
}
getCompanies(){
this.getData("getcompanies").then(companies => {
this.dataCompanies = companies
})
}
let arrResponse = {data: ['x']};
let objResponse = {data: {getcompanies: 'x'}};
console.log(arrResponse.data[0]);
console.log(Object.values(objResponse.data)[0]);
response.data[0] would work if data was an array. To get the first-and-only element of an object, use Object.values(response.data)[0] instead. Object.values converts an object to an array of its values.
Its counterparts Object.keys and Object.entries likewise return arrays of keys and key-value tuples respectively.
Note, order isn't guaranteed in objects, so this is only predictable in your situation because data has exactly a single key & value. Otherwise, you'd have to iterate the entry tuples and search for the desired entry.
firstValue
Let's begin with a generic function, firstValue. It will get the first value of an object, if present, otherwise it will throw an error -
const x = { something: "foo" }
const y = {}
const firstValue = t =>
{ const v = Object.values(t)
if (v.length)
return v[0]
else
throw Error("empty data")
}
console.log(firstValue(x)) // "foo"
console.log(firstValue(y)) // Error: empty data
getData
Now write a generic getData. We chain our firstValue function on the end, and be careful not to add a console.log or .catch here; that is a choice for the caller to decide -
getData(url) {
return this
.sendMicroServiceRequest({ method: "GET", url })
.then(response => {
if (response.data)
return response.data
else
return Promise.reject(response)
})
.then(firstValue)
}
Now we write getCompanies, getUsers, etc -
getCompanies() {
return getData("api/authenticated/function/getcompanies")
}
getUsers() {
return getData("api/authenticated/function/getusers")
}
//...
async and await
Maybe you could spruce up getData with async and await -
async getData(url) {
const response =
await this.sendMicroServiceRequest({ method: "GET", url })
return response.data
? firstValue(response.data)
: Promise.reject(response)
}
power of generics demonstrated
We might even suggest that these get* functions are no longer needed -
async getAll() {
return {
companies:
await getData("api/authenticated/function/getcompanies"),
users:
await getData("api/authenticated/function/getusers"),
devices:
await getData("api/authenticated/function/getdevices"),
// ...
}
}
Above we used three await getData(...) requests which happen in serial order. Perhaps you want all of these requests to run in parallel. Below we will show how to do that -
async getAll() {
const requests = [
getData("api/authenticated/function/getcompanies"),
getData("api/authenticated/function/getusers"),
getData("api/authenticated/function/getdevices")
]
const [companies, users, devices] = Promise.all(requests)
return { companies, users, devices }
}
error handling
Finally, error handling is reserved for the caller and should not be attempted within our generic functions -
this.getAll()
.then(data => this.render(data)) // some Vue template
.catch(console.error)
I'm work with NodeJS and Sequelize. I have the following issue:
Read the Settings Table:
Settings.findOne({where: {
user_id: data
}})
.then(settings => {
// Next request
});
I need to save the settings.device (Example) outside of the .then block.
But if I do that like
var device;
Settings.findOne({where: {
user_id: data
}})
.then(settings => {
device = settings.device;
});
It doesn't work.
Already the error output undefined
The output in .then result block with console.log(settings.device); works perfect.
Update
I need it like:
var array = [];
// Get Settings from table
Settings.findOne({where: {
user_id: data
}})
.then(settings => {
// Get token from other Table
Example.findOne({where: {
user_id: data
}})
.then(example => {
// push to array
array.push({
"user_id" : data,
"device":settings.device, // output: settings.device is undefined
"token": example.token
});
});
});
// Send array to client
This is really a question of how to handle multiple resolved values in a Promise chain. You can search for that and see lots of great examples on how to handle it. For example, you could return an array or object in each then handler, or re-assign values to higher-scoped variables (as you're doing with settings). I've used both methods heavily in the past, and the resulting code is obviously inelegant and not fun to write.
However, async/await is readily available in Node and simplifies your code quite a bit:
const array = [];
// Get settings.
const settings = await Settings.findOne({where: {
user_id: data
}});
// Get token.
const example = await Example.findOne({where: {
user_id: data
}});
array.push({
user_id : data,
device: settings.device,
token: example.token
});
Sequelize return the model object you can get value by dataValue
console.log(settings.dataValues.device);
or if you want lean data
Settings.findOne({where: {
user_id: data,
raw:true,
}})
.then(settings => {
device = settings.device;
console.log(device);
});
I'm calling an API and receiving an array of results, I'm checking for pagination and if more pages exist I call the next page, repeat until no more pages.
For each array of results, I call another endpoint and do the exact same thing: I receive an array of results, check for another page and call endpoint again. Wash, rinse repeat.
For instance:
I want to grab a list of countries that might be a paginated response, then for each country I want to grab a list of cities, which might also be paginated. And for each city I execute a set of transformations and then store in a database.
I already tried this, but got stuck:
const grabCountries = Observable.create(async (observer) => {
const url = 'http://api.com/countries'
let cursor = url
do {
const results = fetch(cursor)
// results = {
// data: [ 'Canada', 'France', 'Spain' ],
// next: '47asd8f76358df8f4058898fd8fab'
// }
results.data.forEach(country => { observer.next(country) })
cursor = results.next ? `${url}/${results.next}` : undefined
} while(cursor)
})
const getCities = {
next: (country) => {
const url = 'http://api.com/cities'
let cursor = url
do {
const results = fetch(cursor)
// results = {
// data: [
// 'Montreal', 'Toronto',
// 'Paris', 'Marseilles',
// 'Barcelona', 'Madrid'
// ],
// next: '89ghjg98nd8g8sdfg98gs9h868hfoig'
// }
results.data.forEach(city => {
`**** What do I do here?? ****`
})
cursor = results.next ? `${url}/${results.next}` : undefined
} while(cursor)
}
}
I tried a few approaches:
Making a subject (sometimes I'll need to do parallel processed base on the results of 'grabCountries'. For example I may want to store the countries in a DB in parallel with grabbing the Cities.)
const intermediateSubject = new Subject()
intermediateSubject.subscribe(storeCountriesInDatabase)
intermediateSubject.subscribe(getCities)
I also tried piping and mapping, but it seems like it's basically the same thing.
As I was writing this I thought of this solution and it seems to be working fine, I would just like to know if I'm making this too complicated. There might be cases where I need to make more that just a few API calls in a row. (Imagine, Countries => States => Cities => Bakeries => Reviews => Comments => Replies) So this weird mapping over another observer callback pattern might get nasty.
So this is what I have now basically:
// grabCountries stays the same as above, but the rest is as follows:
const grabCities = (country) =>
Observable.create(async (observer) => {
const url = `http://api.com/${country}/cities`
let cursor = url
do {
const results = fetch(cursor)
// results = {
// data: [
// 'Montreal', 'Toronto',
// 'Paris', 'Marseilles',
// 'Barcelona', 'Madrid'
// ],
// next: '89ghjg98nd8g8sdfg98gs9h868hfoig'
// }
results.data.forEach(city => {
observer.next(city)
})
cursor = results.next ? `${url}/${results.next}` : undefined
} while (cursor)
})
const multiCaster = new Subject()
grabCountries.subscribe(multiCaster)
multiCaster.pipe(map((country) => {
grabCities(country).pipe(map(saveCityToDB)).subscribe()
})).subscribe()
multiCaster.pipe(map(saveCountryToDB)).subscribe()
tl;dr - I call an API that receives a paginated set of results in an array and I need to map through each item and call another api that receives another paginated set of results, each set also in an array.
Is nesting one observable inside another and mapping through the results via 'callApiForCountries.pipe(map(forEachCountryCallApiForCities))' the best method or do you have any other recommendations?
Here's the code that should work with sequential crawling of next url.
You start with a {next:url} until res.next is not available.
of({next:http://api.com/cities}).pipe(
expand(res=>results.next ? `${url}/${results.next}` : undefined
takeWhile(res=>res.next!==undefined)
).subscribe()
OK, so I have spent a lot of brain power on this and have come up with two solutions that seem to be working.
const nestedFlow = () => {
fetchAccountIDs.pipe(map(accountIds => {
getAccountPostIDs(accountIds) // Has the do loop for paging inside
.pipe(
map(fetchPostDetails),
map(mapToDBFormat),
map(storeInDB)
).subscribe()
})).subscribe()
}
const expandedflow = () => {
fetchAccountIDs.subscribe((accountId) => {
// accountId { accountId: '345367geg55sy'}
getAccountPostIDs(accountId).pipe(
expand((results) => {
/*
results : {
postIDs: [
131424234,
247345345,
],
cursor: '374fg8v0ggfgt94',
}
*/
const { postIDs, cursor } = results
if (cursor) return getAccountPostIDs({...accountId, cursor})
return { postIDs, cursor }
}),
takeWhile(hasCursor, true), // recurs until cursor is undefined
concatMap(data => data.postIDs),
map(data => ({ post_id: data })),
map(fetchPostDetails),
map(mapToDBFormat),
map(storeInDB)
).subscribe()
})
}
Both seem to be working with similar performance. I read some where that leaving the data flow is a bad practice and you should pipe everything, but I don't know how to eliminate the first exit in the 'expandedFlow' because the 'expand' needs to call back an observable, but maybe it can be done.
Now I just have to solve the race condition issues from the time the 'complete' is called in getAccountPostIDs the the last record is stored in the DB. Currently in my test, the observer.complete is finishing before 3 of the upsert actions.
Any comments are appreciated and I hope this helps someone out in the future.
What you need is the expand operator. It behaves recursively so it fits the idea of having paginated results.