Best way to navigate throught a JSON in Node while validating the path - node.js

Question

I'm trying to get some info out of a API call in Nodejs, structured something like a JSON:
{
"generated":"2019-11-04T09:34:11+00:00",
"event":{
"id":"19040956",
"start_":"2019-11-16T11:30:00+00:00",
"event_context":{
"sport":{
"id":"1",
"name":"Soccer"
}
}
}
}
I'm not sure about the presence of none of these fields(Json could be incomplete).
Is there a better way to get the value of "name" in JSON.event.event_context.sport.name without an ugly if to not get errors like "cannot get field 'sport' of undefined"?
Currently, I'm doing
if(json.event && json.event.event_context && json.event.event_context.sport) {
return json.event.event_context.sport.name;
}
Is there a better way?
Thank you!

Answer 1

what do you mean by saying "I'm not sure about the presence of none of these fields"?
i don't understand what your'e trying to achieve.

Answer 2

Looks like there is also an interesting package that will allow more conditions on searching json :
https://www.npmjs.com/package/jspath
let getNested = (path, obj) => {
return path.split(".").reduce( getPath, obj);
}
let getPath = (path, key) => {
return (path && path[key]) ? path[key] : null
}
let test = {
"foo": "bar",
"baz": { "one": 1, "two": ["to", "too", "two"] },
"event": { "event_context": { "sport": { "name": "soccer" } } }
}
console.log(getNested("none", test))
console.log(getNested("baz.one", test))
console.log(getNested("baz.two", test))
console.log(getNested("event.event_context.sport.name", test))

Answer 3

You can use lodash get to get a potentially deeply-nested value, and also specify a default in case it doesnt exist.
Example
const _ = require('lodash');
const my_object = {
"generated":"2019-11-04T09:34:11+00:00",
"event":{
"id":"19040956",
"start_":"2019-11-16T11:30:00+00:00",
"event_context":{
"sport":{
"id":"1",
"name":"Soccer"
}
}
};
_.get(my_object, 'event.event_context.sport.name'); // "Soccer"
_.get(my_object, 'event.event_context.sport.nonExistentField', 'default val'); // "default val"
Article: https://medium.com/#appi2393/lodash-get-or-result-f409e73e018b

Answer 4

You can check by using a function to check object keys like :
function checkProperty(checkObject, checkstring){
if(!checkstring)
return false;
var propertiesKeys = checkstring.split('.');
propertiesKeys.forEach(element => {
if(!checkObject|| !checkObject.hasOwnProperty(element)){
return false;
} else {
checkObject= checkObject[element];
}
})
return true;
};
var objectToCheck = {
"generated":"2019-11-04T09:34:11+00:00",
"event":{
"id":"19040956",
"start_":"2019-11-16T11:30:00+00:00",
"event_context":{
"sport":{
"id":"1",
"name":"Soccer"
}
}
}
}
if (checkProperty(objectToCheck ,'event.event_context.sport.name'))
console.log('object to find is : ', objectToCheck .event.event_context.sport.name;)

Answer 5

Yeah there are better ways!
For example, you could use lodash's get() method to reach a nested value.
var object = { 'a': [{ 'b': { 'c': 3 } }] };
_.get(object, 'a[0].b.c');
// => 3
But there is also a native solution.
Currently (11.2019) only Babel can handle this.
I am speaking of Optional chaining. It's new in the Ecmascript world.
Why I like it? Look here!
// Still checks for errors and is much more readable.
const nameLength = db?.user?.name?.length;
What happens when db, user, or name is undefined or null? With the optional chaining operator, JavaScript initializes nameLength to undefined instead of throwing an error.
If you are using Babel as a compiler then you could use it now.
Related link: https://v8.dev/features/optional-chaining