I am having trouble finding the value of a property in an array based on the value of another property. I am trying to assign the variable x with the value of sensors.type when searching for a specific sensorID. For example in the table below if I have the value of the sensor ID (yellow box) I am trying to assign the value of the type (red box) to the variable x.
I load an array 'sensors' with data from a PostgreSQL database with the following code:
var sensors = [];
var pgp = require('pg-promise')(options);
var connection = "postgres://xxxxxxx:yyyyyyy#xxx.xxx.xxx.xxx/heatmap"
var db = pgp(connection);
getSensors();
setInterval(getSensors,10000)
function getSensors(){
var q = "select * from sensors order by id"
db.query(q)
.then(function (data) {
data.forEach((s)=>{
sensors[s.mac.trim()] = s
console.log(s)
})
}, function (reason) {
console.log(reason);
})
.catch(function (error) {
console.err("Query error, "+error);
});
}
when I run the command console.table(sensors) this is what I see ..
Also I can see details for each record with console.dir(sensors) ...
I have an input string which I parse to get the sensorId I want to search the array for and can verify it exists with a valid value via console.log output.
var sensorId = rawData.substring(6,18);
var sensorRecord = sensors[sensorId];
I cannot seem to find a way of searching the array for the sensorType and assigning the value of the associated 'type' from the array to a variable.
I thought the following would:
var sensorType = sensors[sensorId].type;
But it returns the following error:
Would appreciate any help and guidance.
Related
I'm currently writing a small API for a cooking app. I have a Recipe model and would like to implement sorting by columns based on the req Parameter given.
I'd like to sort by whatever is passed in the api call. the select parameter works perfectly fine, I can select the columns to be displayed but when I try to sort anything (let's say by rating) the return does sort but I'm not sure what it does sort by.
The code i'm using:
query = Recipe.find(JSON.parse(queryStr));
if(req.query.select){
const fields = req.query.select.split(',').join(' ');
query = query.select(fields);
}
if(req.query.sort){
const sortBy = req.query.sort.split(',').join(' ');
query = query.sort({ sortBy: 1 });
} else {
query = query.sort({ _id: -1 });
}
The result, when no sorting is set: https://pastebin.com/rPLv8n5s
vs. the result when I pass &sort=rating: https://pastebin.com/7eYwAvQf
also, when sorting my name the result is also mixed up.
You are not using the value of sortBy but the string "sortBy". You will need to create an object that has the rating as an object key.
You need the sorting object to look like this.
{
rating: 1
}
You can use something like this so it will be dynamic.
if(req.query.sort){
const sortByKey = req.query.sort.split(',').join(' ');
const sortByObj = {};
sortByObj[sortByKey] = 1; // <-- using sortBy as the key
query = query.sort(sortByObj);
} else {
query = query.sort({ _id: -1 });
}
I'm not able to get the rows on condition.
The condition is based on a ID, but this ID is a value of a key inside an object that is inside an array, also the array is inside another array.
So I have
Cinema (ARRAY) -> ARRAYS (0,1,2,3....) -> OBJECTS inside each ARRAY
I need the object where cinema_id_db is matched.
For example this code return the data of
cinema[0][0]['cinema_id_db'] = ObjectId("5b44a78b38be3aeb31f092cb")
code
{ "cinema.0.0.cinema_id_db" : ObjectId("5b44a78b38be3aeb31f092cb")}
I need something like
cinema[x][y]['cinema_id_db'] = ObjectId("5b44a78b38be3aeb31f092cb")
This is how the db looks
you can get this value you want to get, this way
let cinema_id_db = cinema[0][0].cinema_id_db
OR
var ciname_ids_db = [];
var index = 0;
cinema.forEach(element => {
element.forEach(elem => {
ciname_ids_db[index++] = elem.cinema_id_db
})
})
I've a node.js api in which user sends the required fields as an array to be fetched from the mongodb database. I need to find the data of that fields using Find query. I've written forEach statement to loop through that array and got the array elements. But when I try to get the results by inserting the array elements in the query, it doesn't giving the required results. Could any one please help me in resolving the issue by seeing the code below?
templateLevelGraphData: async function(tid,payload){
let err, templateData, respData = [], test, currentValue;
[err,templateData] = await to(Template.findById(tid));
var templateId = templateData.templateId;
payload.variables.forEach(async data=>{
console.log(data); //data has the array elements like variables=["humidity"]
[err, currentValue] = await to(mongoose.connection.db.collection(templateId).find({},{data:1}).sort({"entryDayTime":-1}).limit(1).toArray());
console.log(currentValue);
});
return "success";
}
The expected output is,
[ { humidity: 36 } ]
But I'm getting only _id like,
[ { _id: 5dce3a2df89ab63ee4d95495 } ]
I think data is not applying in the query. But I'm printing the data in the console where it's giving the correct results by displaying the array elements like, humidity. What I need to do to make it work?
When you are passing {data: 1} you are passing an array where is expecting name of column.
You have to create an object where the keys are going to be the elements of the array and set them to 1.
const projection = data.reduce((a,b) => (a[b]=1, a), {});
[...] .find({}, projection) [...]
Actually I got the solution.
for(let i=0;i<payload.variables.length;i++){
var test = '{"'+ payload.variables[i] +'":1,"_id":0}';
var query = JSON.parse(test);
[err, currentValue] = await to(mongoose.connection.db.collection(templateId).find({"deviceId":deviceId},query).sort({"entryDayTime":-1}).limit(1).toArray());
console.log(currentValue); //It's giving the solution
}
I use firebase on node.js .
My given structure should look like this:
{
...
batch-1:
id-1(suppose):
name:...
phone:...
id-2:
...
id-3:
...
batch-2:
...
batch-3:
...
...
batch-n:
...
}
How can I get an id-1 object by its identifier in such an architecture?
Does the database have to go around all the batches?
Is there a better solution?
The main task: Create a batch with many objects that will have SHORT and a UNIQUE identifier and optimally receive data by this identifier
To search for a particular ID that is a child of a list of unknown IDs, you need to use orderByChild(). In your use case, you are looking for a particular ID in a list of batch IDs. If you used orderByChild() on this list, you would get back results for each and every batch ID, even if it didn't have the ID you wanted. This is because even null (non-existant) values are included (and sorted at the start) in the results. To get the data of the desired ID, you would get the data for the last result of the query, which if it existed, would be sorted to the end of the list. Note that if the desired ID doesn't exist, the last result (if there are any results) would have a null value. To return only the last result of the query, you would use limitToLast(1).
Putting this all together, gives the following code:
let idToFind = "unique-id-1";
let batchesRef = firebase.database().ref(); // parent key of "batch-1", "batch-2", etc.
// assumed to be the database root here
batchesRef.orderByChild(idToFind).limitToLast(1).once('value')
.then((querySnapshot) => {
if (!querySnapshot.numChildren()) { // handle rare no-results case
throw new Error('expected at least one result');
}
let dataSnapshot;
querySnapshot.forEach((snap) => dataSnapshot = snap); // get the snapshot we want out of the query's results list
if (!dataSnapshot.exists()) { // value may be null, meaning idToFind doesn't exist
throw new Error(`Entry ${idToFind} not found.`);
}
// do what you want with dataSnapshot
console.log(`Entry ${idToFind}'s data is:`, dataSnapshot.val());
})
.catch((error) => {
console.log("Unexpected error:", error);
})
For small data sets, the above code will work just fine. But if the list of batches starts growing quite large, you may wish to build an index that maps a particular ID to the batch ID that contains it.
Here is my method which allows you to search by id or to search by key value such as email uniqueemail
// gets primary key
const getSnapshotValKey = snapshot => (Object.keys(snapshot).length > 0 ? Object.keys(snapshot)[0] : null)
const getUser = async ({ id, key, value }) => {
let user = null
const ref = id ? '/users/' + id : 'users'
const userRef = admin.database().ref(ref)
const valueRef = id ? userRef : await userRef.orderByChild(key).equalTo(value)
const snapshot = await valueRef.once('value')
const val = snapshot.val()
if (val) {
const key = id || getSnapshotValKey(val)
user = {
id: key,
...(id ? val : val[key]),
}
}
return user
}
I'm trying to get the object id after adding it to the db (using collection.insert)
mongoose.model('Persons').collection.insert(person, function(err, newPerson) {
console.log('lets see you', newPerson);
});
and from the console I'm getting only result: { ok: 1, n: 1 } in stand of the new obj, any ideas how can I rich to the new object ?
thanks!
You can use save() here
var Persons = mongoose.model('Persons');
var personJSON = {
..... // persons schema values you want to insert
};
var person = new Persons(personJSON);
var result = yield person.save();
result variable will contain all the fields you inserted along with _id