Cannot set properties of undefined by iteration the nested JSON

user_10114552 0
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I have a nested JSON, this is structured as follows: enter image description here

As you can see the JSON is called bwaResult and in this object there are three big groups. These groups are called actBwa, fcBwa and planBwa. These groups contain years and yearlyResults(sums) which also have years. I would like to assign the values to the individual years. That means in 2020 you would have actBwa, fcBwa, planBwa and the yearlyResults values and the same for the other years.

My Code:

 const plMonthResults = {};
        const plMonth = resp.success ? resp.bwaResult : null; // JSON-DATA
        delete resp.success;
        if (plMonth && plMonth !== null && Object.keys(plMonth)) {
          let count = 0;
          for (const bwaType in plMonth) {
            const plMonthData = plMonth[bwaType]; // Here I get actBwa, fcBwa, planBwa
            if (count === 0) {
              for (const yearKey of Object.keys(plMonthData)) {
                plMonthResults[yearKey] = {}; // Sort by years
              }
            }
            for (const yearKeyInPlMonth in plMonthData) {
              plMonthResults[yearKeyInPlMonth][bwaType] = plMonthData[yearKeyInPlMonth]; // Here then arises the error
            }
            count += 1;
          }
        }

When I run the code then I get the following error:

ERROR TypeError: Cannot set properties of undefined (setting 'fcBwa')

I guess since actBwa only has 2020 and the other groups have more years there is a problem finding fcBwa and iterating further or am I seeing this wrong? Can you tell me how to solve this problem?

UPDATE my work in stackblitz: https://stackblitz.com/edit/read-local-json-file-service-udqvck?file=src%2Fapp%2Fapp.component.ts

typescript json javascript
1 Answers

It seems like you're using count to copy the keys only once, but that means you will only have the keys of the first object (in this case actBwa). You can instead go through the key of each object, but make sure you don't override the existing ones. So remove the count and modify the look like this

       for (const yearKey of Object.keys(plMonthData)) {
          plMonthResults[yearKey] = plMonthResults[yearKey] ?? {};
        }

You can even remove this loop and include the check into the main one:

   for (const yearKeyInPlMonth in plMonthData) {
          plMonthResults[yearKeyInPlMonth] = plMonthResults[yearKeyInPlMonth] ?? {};
          plMonthResults[yearKeyInPlMonth][bwaType] = plMonthData[yearKeyInPlMonth]; 
        }

Let me know if that gives you the result you're after

user_44348500
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