creating dynamic array in a dynamic javascript object (key/value pair)

Question

I've thought that this is how the data will look for every query operation having a unique id (which is 1 & 2 in below example).

var finalData = {
    queryData: {
        "1": { // here "1" will be the auto-incrementing query operation id generated from somewhere
            jiraList: ["abc-123", "bcd-234"],
            jiraDetail: [
                {
                    jiraKey: "abc-123",
                    status: "Closed"
                },
                {
                    jiraKey: "bcd-234",
                    status: "Open"
                }
            ]
        },
        "2": {
            jiraList: ["xyz-987", "wxy-876"],
            jiraDetail: [
                {
                    jiraKey: "xyz-987",
                    status: "Open"
                },
                {
                    jiraKey: "wxy-876",
                    status: "Closed"
                }
            ]
        }
    }
};

I've a function which accepts the query's unique id & jira List (which is already an array):

var addJiraList = function (key, jiraList) {
    // sample params will be key: 1, jiraList: ['abc-123', 'bcd-234']
    finalData.queryData[key] = {jiraList: jiraList};
};

So the above function creates a key value pair in finalData.queryData if not present, and if present, it'll add/update jiraList with required values to it. This works.

I've another function which accepts the query's unique id & a single jiraDetail which is:

var addJiraData = function (queryKey, extractedData) {
    // sample params will be queryKey: 1, extractedData: { jiraKey: "abc-123", status: "Closed" }
    finalData.queryData[queryKey]["jiraDetail"].push(extractedData);
};

I want to push the extractedData coming as parameter in the array finalData.queryData.2.jiraDetail.

Now the problem is that finalData.queryData.<queryId> is dynamic & jiraDetail is an array inside it. So for the first time if queryKey is 1 & extractedData is {something}, how would I add one item extractedData into an array (jiraDetail) of queryKey which is not even created.

At present it is throwing finalData.queryData[queryKey] is undefined error which is valid as I cannot add inside an object which is not yet created.

Solution in my mind is to check if finalData.queryData[queryKey] is undefined and if it is undefined then first create the object with empty jiraDetail array in it so that the following line will not throw undefined error.

finalData.queryData[queryKey]["jiraDetail"].push(extractedData);

There must be something better that can be done which I'm at present unable to think & search. I want to know how would you handle this situation?

Here's the link of the file which will be updated based on the answer that I'll get here.

https://github.com/sunilrebel/spann-jira/blob/master/lib/storageSystem.js

You should be checking for the keys existence either way - it's not a big deal... not sure why that's a problem? — tymeJV
– tymeJV, Commented Dec 29, 2014 at 20:37
It's not a problem actually, just confirming that if the function is called thousand times, checking every time existence is a big deal or not. Because it'll actually create space once & rest time it'll skip the if part. — Sunil Kumar
– Sunil Kumar, Commented Dec 30, 2014 at 4:01

Mouser · Accepted Answer · 2014-12-29 22:26:42Z

1

You indeed need to check if the key is present in finalData.queryData and if not create. Look at this solution:

var addJiraData = function (queryKey, extractedData) {
    if (!finalData.queryData[queryKey] || !finalData.queryData[queryKey]["jiraDetail"])
    {
        //one of the objects isn't present, let's create it.
        !finalData.queryData[queryKey] ? addJiraList(queryKey, []) : null; //add missing queryKey and empty array as jiraList.
        finalData.queryData[queryKey]["jiraDetail"] = []; //create empty jiraDetail array.
    }
    //then fill it with data, since it is available now.
    finalData.queryData[queryKey]["jiraDetail"].push(extractedData);
};

answered Dec 29, 2014 at 22:26

Mouser

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2 Comments

Sunil Kumar Over a year ago

Hey Thanks. That's exactly what I thought. Seems checking every time is not a big deal even if the function is called thousand of times.

Mouser Over a year ago

Data consistency is in this case more important. The function isn't too heavy, so that should not effect performance.

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