Reference JSON variable with string acquired from other JSON

Question

I have 2 JSON files.

file 1

{
  object: {
    variable: true
  }
}

and file 2

{
  object2: {
    tag: "object.variable
  }
}

What I am stuck on is that I need to, in one javascript file, get the tag from file 2 and use it to reference the variable in file 1.

I have gotten both file 1 as a JSON and have gotten 'tag' from file 2 in my code. However I am entirely lost as to how I can go about using the string "object.variable" to get the value of object.variable from file 1.

PS (I tried using eval but had no luck, though I would like to avoid it at all costs if possible.)

Your json is invalid. You don't use a ; in a json object. Also you have " in your object2 but if you are accessing a key from object we wouldn't need that. How are you actually accessing it? Give us the actual code. — basic
– basic, Commented Jul 3, 2019 at 19:21
Apologies on the JSON format. Those are example files. The real ones I'm using work to get the String and the JSON itself. The only thing I have tried that even got close was eval(string) where string was object.variable. This failed as it said periods were not defined for eval(). @IMustBeSomeone — spaff
– spaff, Commented Jul 3, 2019 at 19:28

Vishnu · Accepted Answer · 2019-07-03 19:40:17Z

3

Did you mean something like this ?

var file1 = {
  object: {
    variable: true
  }
};

var file2 = {
  object2: {
    tag: "object.variable"
  }
};

var result =  file2.object2.tag.split('.').reduce((a, b) =>  a ? a[b] : null, file1);


console.log(result);

answered Jul 3, 2019 at 19:40

Vishnu

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4 Comments

spaff Over a year ago

I have only used .reduce a limited number of times so apologies if this is a silly question, but are 'a' and 'b' "object" and "variable" respectively?

Vishnu Over a year ago

a is for the accumulator, which is file1(passed as second param for reduce function) and b is each item in the array of tagnames(seperated by a dot).

spaff Over a year ago

So if tag was something like "object.one.two.three.variable", it would still work given that path exists?

spaff Over a year ago

Don't FULLY understand how it works, but it works. Great answer and kudos for making it a one-liner!

Shrijan Tiwari · Accepted Answer · 2019-07-03 19:43:15Z

1

This could be the possible solution :

var query = {
  object2: {
    tag: "data.object.variable"
  }
}


var data = {
  object: {
    variable: true
  }
}

console.log(eval(query.object2.tag));

answered Jul 3, 2019 at 19:43

Shrijan Tiwari

7136 silver badges19 bronze badges

2 Comments

spaff Over a year ago

This seems to work in the code snippet but when I run it in my file, I received "UnhandledPromiseRejectionWarning: ReferenceError: period is not defined". I had tried something near identical to this answer but couldn't get around that error.

Intervalia Over a year ago

Avoid eval if you can not be 110% certain of the source data. Instead look at the code supplied by @Vishnu

Super Kai - Kazuya Ito · Accepted Answer · 2023-05-29 06:35:25Z

0

But if you want to reference to the same json, this is one method that you can:

jsn = {
    x : 2,
    y : ()=>(jsn.x*2)
}

This way, you can refference one varriable to another varriable in same json

edited May 29, 2023 at 6:35

Super Kai - Kazuya Ito

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answered May 28, 2023 at 18:29

Yash Goswami

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