How to map values between JS objects?

Question

How to map values of one object to other if keys matched, trying to assign values here additionalData.value =userParams[prop] ? userParams[prop] : ''; however it pushing empty string any idea what has implemented wrong here ? or any better approach to achieve this task

const getParams = (userParams) => {
    const interactionData = [];
    const interactionDataDict  = {
        firstName: [{key: "FIRST_NAME", defaultValue: null}],
        lastName: [{key: "LAST_NAME", defaultValue: null}],
        SourceSystem: [{key: "SOURCE_SYSTEM", defaultValue: null}]
    };
    for (const prop in interactionDataDict) {
        if (prop) {
            for (const val of interactionDataDict[prop]) {
                const additionalData = {};
                additionalData.key = val.key;
                if (val.defaultValue) {
                    additionalData.value = val.defaultValue;
                }
                else {
                    additionalData.value =
                        userParams[prop] ? userParams[prop] : '';
                }
                interactionData.push(additionalData);
            }
        }
    }
    return interactionData;
}

const args = { 
    firstName: "John",
    lastName: "Hayne",
    sourceSystem: "HTS"
}

console.log(getParams(args))

expected output

[{"key":"FIRST_NAME","value":"John"},{"key":"LAST_NAME","value":"Hayne"},{"key":"SOURCE_SYSTEM","value":"HTS"}]

It looks as though there's a typo in interationDataDict. Why is the key SourceSystem capitalized and the others are not. If you change, this, I think your problem goes away. — Scott Sauyet
– Scott Sauyet, Commented Sep 24, 2020 at 21:16
to have pre assignment for the default value as null i had to create interationDataDict as an array — hussain
– hussain, Commented Sep 24, 2020 at 21:18
@hussain: The point is why is interactionDataDict.firstName the single-element array [{key: "FIRST_NAME", defaultValue: null}] instead of the plain object {key: "FIRST_NAME", defaultValue: null}? — Scott Sauyet
– Scott Sauyet, Commented Sep 24, 2020 at 21:24

Nina Scholz · Accepted Answer · 2020-09-24 21:13:15Z

1

You could map the entries and get key and value for the new objects.

function getParams(userParams) {
    const interactionDataDict = { firstName: [{ key: "FIRST_NAME", defaultValue: null }], lastName: [{ key: "LAST_NAME", defaultValue: null }], SourceSystem: [{ key: "SOURCE_SYSTEM", defaultValue: null }] }; 
    return Object
        .entries(interactionDataDict)
        .map(([k, [{ key, defaultValue }]]) =>
            ({ key, value: userParams[k] || defaultValue })
        );
}

const args = { firstName: "John", lastName: "Hayne", sourceSystem: "HTS" }

console.log(getParams(args));

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answered Sep 24, 2020 at 21:13

Nina Scholz

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6 Comments

hussain Over a year ago

Can you simplify this it is throwing alot of errors with es6 code i guess

Scott Sauyet Over a year ago

@hussain: what environment are you running in that ES6 doesn't work?

hussain Over a year ago

@ScottSauyet gettign this error Type 'unknown' must have a '[Symbol.iterator]()' method that returns an iterator.ts(2488

Scott Sauyet Over a year ago

@Nina: Note, though, that if interactionDataDict is really local to this function (instead of an additional parameter or something in a higher scope), you might as well store it as the result of that Object.entries call, something like [['firstName', {key: ... defaultValue: ...}], ['lastName', {...}], ...], and then have the function consist only of the map call.

hussain Over a year ago

@ScottSauyet that might be the issue interactionDataDict is not local to this function it is private attribute of the class , i added in the question in local scope to better understand instead of adding class code but even after changing to this. interactionDataDict it didn't work

|

Scott Sauyet · Accepted Answer · 2020-09-24 21:40:42Z

0

I wrote an answer independently, but ended up with the same logical solution as Nina. But I structured it somewhat differently, and it might be of interest:

const buildDefaults = (dict) => (args) => 
  Object 
    .entries (dict)
    .map (([k, [{key, defaultValue}]]) => ({key, value: args [k] || defaultValue}))


const getParams = buildDefaults ({
  firstName: [{key: "FIRST_NAME", defaultValue: null}],
  lastName: [{key: "LAST_NAME", defaultValue: null}],
  sourceSystem: [{key: "SOURCE_SYSTEM", defaultValue: null}]
})

const args = { 
  firstName: "John",
  lastName: "Hayne",
  sourceSystem: "HTS"
}

console .log (getParams (args))

.as-console-wrapper {max-height: 100% !important; top: 0}

Here we write the generic function buildDefaults that takes the dictionary and returns a function that takes args and fills in your output the way you want. Then getParams is created by calling it with your dictionary.

If, as discussed in the comments, you wanted to remove the array wrappers in the dictionary, so that it looks like this:

{
    firstName: {key: "FIRST_NAME", defaultValue: null},
    lastName: {key: "LAST_NAME", defaultValue: null},
    sourceSystem: {key: "SOURCE_SYSTEM", defaultValue: null}
}

then you could just replace it in the destructured parameter by replacing this line:

    .map (([k, [{key, defaultValue}]]) => ({key, value: args [k] || defaultValue}))

with this:

    .map (([k, {key, defaultValue}]) => ({key, value: args [k] || defaultValue}))

answered Sep 24, 2020 at 21:40

Scott Sauyet

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2 Comments

hussain Over a year ago

i think its just this line if you can help how do i map userParams instead of writing complex code additionalData.value = eci[prop] ? eci[prop] : userParams[prop] ? userParams[prop] : ''; in my orginal code

Scott Sauyet Over a year ago

@hussain: I don't know what that is. eci? My answer and Nina's answer both seem to do what you need. But my first comment on the question shows the smallest change to get this working. I find either of the answers much simpler than your code, so we have very different ideas about "complex code". Sorry.

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