How to retrieve desired JSON object from firebase database in JSON formate using Node js

Question

I m new to Node js and firebase. I m trying to fetch JSON data stored in my firebase database depending upon some search criteria.

In the following example:

See this Image

The variable childname is key to whose value we have to search (col1) and findvalue is value for that key( value for col1 to be)

for this I tried the following codes:

function searchKeyValue(headNode,childname,findvalue) {
  var ref = firebase.database().ref("data/"+headnode);
  ref.orderByKey().on("child_added", function(snapshot) {
    //extracting Query
    ref.orderByChild(childname).equalTo(findvalue).on("value",function (snapshot) {
      console.log(snapshot.val());
    });//end of Query
  });//end oder by key
}// end of function

function searchKeyValue(headnode,childname,findvalue) {
  var ref = firebase.database().ref("data");
  nextref=ref.child(headnode);
  nextref.orderByChild(childname).equalTo(findvalue).on("value",function (snapshot) {
    console.log(JSON.stringify(snapshot.val()));
  })
}

but both fails to provide me the desired output: OUTPUT DESIRED is :

{1:"152",2:"233.69",3:"-191.7",4:"133.69",5:"-199.769",6:"AMUKH",7:"4",{"port":4},8:"NTP",9:{"Dup":12345}]}

But getting:

{"-KOZ2Md3NZ_vWddAIBj3":[null,"152","233.69","-191.7","133.69","-199.769","AMUKH","4",{"port":4},"NTP",{"Dup":12345}]}

[Note: I missed all keys of my saved data I m getting only values to that keys...]

Frank van Puffelen · Accepted Answer · 2016-08-07 23:08:13Z

When you execute a query against the Firebase Database, there will potentially be multiple results. So the snapshot contains a list of those results. Even if there is only a single result, the snapshot will contain a list of one result.

I can't figure out what your first snippet is supposed to do. But the second snippet can be made to work with:

function searchKeyValue(headnode,childname,findvalue) {
  var ref = firebase.database().ref("data");
  nextref=ref.child(headnode);
  nextref.orderByChild(childname).equalTo(findvalue).on("value",function (snapshot) {
    snapshot.forEach(function(childSnapshot) {
      console.log(JSON.stringify(childSnapshot.val()));
    });
  })
}

Alternatively you can listen for child_added, which fires for each child individually:

function searchKeyValue(headnode,childname,findvalue) {
  var ref = firebase.database().ref("data");
  nextref=ref.child(headnode);
  nextref.orderByChild(childname).equalTo(findvalue).on("child_added",function (childSnapshot) {
    console.log(JSON.stringify(childSnapshot.val()));
  })
}

Paul Roub · Accepted Answer · 2018-03-09 20:18:17Z

0

var v = firebase.database().ref().child("data");
var no;
count = 0;
v.on("child_added", snap => {
  count++;
  no = snap.child("HeadNode").val();

  //console.log(no , count);
});

edited Mar 9, 2018 at 20:18

Paul Roub

36.5k27 gold badges88 silver badges95 bronze badges

answered Mar 9, 2018 at 20:05

Viral Patel

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1 Comment

sg7 Over a year ago

Could you elaborate?

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