Concatenating JSON objects in Nodejs

Question

I'm pull data from my data base and converting into to JSON but now I want to place all the JSON data into a single JSON object. I've tried a few methods but I'm not familiar enough with the syntax of javascript and have been unable to find a working solution with proper formatting. I'd like to simply have and object(or two) and continuously add add the new JSON to the older object. I'd prefer not to important any modules for this.

.then(querySnapshot => {
        querySnapshot.forEach(documentSnapshot => {
                myData2 = myData.concat(receiptToDict(documentSnapshot));
                console.log("Found document at", myData2);

            });

});

Can you post a your JSON?

The Reason
– The Reason

2018-07-26 16:47:31 +00:00
Commented Jul 26, 2018 at 16:47 — The Reason
– The Reason, Commented Jul 26, 2018 at 16:47
How would looking at the data inside the JSON help?

Blue
– Blue

2018-07-26 17:31:04 +00:00
Commented Jul 26, 2018 at 17:31 — Blue
– Blue, Commented Jul 26, 2018 at 17:31

Charles Assuncao · Accepted Answer · 2018-07-26 21:33:17Z

2

You can either

var myData2 = Object.assign({}, myData, receiptToDict(documentSnapshot))

or

var myData2 = { ...myData, ...receiptToDict(documentSnapshot) }

EDIT

If you consider the loop, consider you myData declaration outside of the loop and then:

var myData = {};
   ...
.then(querySnapshot => {
    querySnapshot.forEach(documentSnapshot => {
        myData = Object.assign({}, myData, receiptToDict(documentSnapshot))
        console.log("Found document at", myData);
        });

});

2 EDIT

A object can't have the same property twice, so if you have something like

let myData = {};

let dataArray = [
    {value: 01},
    {value: 02},
    {value: 03},
    {value: 04},
    {value: 05}
]

dataArray.forEach((data) => {
    myData = Object.assign({}, myData, data)
})

console.log(myData);

You will end up replacing always the prop "value"so in this case you should do something like:

 var myData = {};
   ...
.then(querySnapshot => {
    querySnapshot.forEach(documentSnapshot => {
        //I don't know which props you obj has so, I suppose it has a unique id for example
        let doc = receiptToDict(documentSnapshot);
        myData[doc.id] = doc;
        console.log("Found document at", myData);
        });

});

edited Jul 26, 2018 at 21:33

answered Jul 26, 2018 at 16:47

Charles Assuncao

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8 Comments

Amit Beckenstein Over a year ago

The spread operator (2nd example) is a good solution, but will only work if you're working with ES6 or later.

Charles Assuncao Over a year ago

@AmitB. Yes, that's true... You should use a transpiler like babel in this case, but anyway you can use the Object.assign if it's not the case :)

Blue Over a year ago

How could this work given I would be defining the variable myData2 inside the loop. Wouldn’t I be overwriting the variable each pass?

Charles Assuncao Over a year ago

@Blue Ok, you can consider you declared myData outside of the loop and then myData = Object.assign({}, myData, receiptToDict(documentSnapshot))... See the edit

Blue Over a year ago

Absolutely, it’s actually declared outside the loop here but I didn’t include it because I’m looking for help in that area as well. I’m not sure how to declare it an empty JSON object. So yea if you can show the best practices for that I’d probably be set.

|

halbertino · Accepted Answer · 2018-07-26 16:47:07Z

0

myData looks like an Array, so you could do:

.then(querySnapshot => {
        querySnapshot.forEach(documentSnapshot => {
               myData.push(receiptToDict(documentSnapshot));

            });

});

answered Jul 26, 2018 at 16:47

halbertino

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