Solving the Angular 11 issue of undefined array mapping

Question

Solving the Angular 11 issue of undefined array mapping

When using an API to retrieve a response array, I encountered an issue trying to map the "id" under the "quiz_records" array as it kept returning undefined. Despite believing that my code was correct, I couldn't figure out the problem.

Here is the snippet of the array:

"quizRemarks": [
        {
            "id": 160,
            "user_id": 1,
            "quiz_id": 18,
            "module_id": 29,
            ...
                },
                ...
            ]

This is the TypeScript code segment I attempted:

this.quiz_records = res['quizRemarks'].map(res => res['quiz_records'].id);
console.log(this.quiz_records);

arrays angular typescript

Answer 1

Answer №1

quizRemarks is a collection of objects that contain an array of quiz_records. You can use the following code snippet to extract a list of ids from the quiz_records:

this.quiz_records = [];
this.quizRemarks.forEach(remark => {
  this.quiz_records.push(...remark.quiz_records.map(rec => rec.id));
});

Answer 2

quizRemarks is a collection of objects that contain an array of quiz_records. You can use the following code snippet to extract a list of ids from the quiz_records:

this.quiz_records = [];
this.quizRemarks.forEach(remark => {
  this.quiz_records.push(...remark.quiz_records.map(rec => rec.id));
});

Answer 3

Answer №2

Check out the following code snippet:

this.quiz_records variable is being populated with ids from the 'quizRemarks' array using Array.map method.

Answer 4

Check out the following code snippet:

this.quiz_records variable is being populated with ids from the 'quizRemarks' array using Array.map method.

Answer 5

Answer №3

Attempting to retrieve an id property from an array may seem impossible at first. However, a solution exists by utilizing a nested map function along with the flat() method available for arrays.

const result = res['quizRemarks'].map(remarks => {
  return remarks['quiz_records'].map(record => record.id);
}).flat();

Answer 6

Attempting to retrieve an id property from an array may seem impossible at first. However, a solution exists by utilizing a nested map function along with the flat() method available for arrays.

const result = res['quizRemarks'].map(remarks => {
  return remarks['quiz_records'].map(record => record.id);
}).flat();

Solving the Angular 11 issue of undefined array mapping

Answer №1

Answer №2

Answer №3

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