如何处理对象数组字符串并合并重复STUDENT_ID的属性值？

Got it, let's work through how to merge those student objects by their STUDENT_ID! Here's a straightforward approach using JavaScript, since your input is a JSON-formatted string:

Step-by-Step Solution #

First, we'll parse the string into a JavaScript array, then use a map to group and merge entries by STUDENT_ID, combining MAJOR values into an array. We'll also add a check to handle any mismatched STATUS values (in case the same student has conflicting statuses).

Code Implementation #

var str_obj = `[ { "STUDENT_ID": "ST001", "MAJOR": "SCIENCE", "STATUS": "1" }, { "STUDENT_ID": "ST002", "MAJOR": "SCIENCE", "STATUS": "1" }, { "STUDENT_ID": "ST002", "MAJOR": "HISTORY", "STATUS": "1" }, { "STUDENT_ID": "ST002", "MAJOR": "MATH", "STATUS": "1" }, { "STUDENT_ID": "ST003", "MAJOR": "HISTORY", "STATUS":"2" } ]`;

// Parse the JSON string into a JS array
const studentsArray = JSON.parse(str_obj);

// Use an object to track merged students by their ID
const mergedStudents = {};

// Iterate over each student entry
studentsArray.forEach(student => {
  const { STUDENT_ID, MAJOR, STATUS } = student;
  
  if (!mergedStudents[STUDENT_ID]) {
    // If the ID doesn't exist yet, initialize a new entry
    mergedStudents[STUDENT_ID] = {
      STUDENT_ID,
      MAJOR: [MAJOR],
      STATUS
    };
  } else {
    // Add the current major to the existing entry's major array
    mergedStudents[STUDENT_ID].MAJOR.push(MAJOR);
    
    // Optional: Warn if there's a status mismatch for the same student
    if (mergedStudents[STUDENT_ID].STATUS !== STATUS) {
      console.warn(`Warning: STUDENT_ID ${STUDENT_ID} has conflicting STATUS values: ${mergedStudents[STUDENT_ID].STATUS} vs ${STATUS}`);
    }
  }
});

// Convert the merged object values back to an array
const finalResult = Object.values(mergedStudents);

// If you need the result as a string again, use JSON.stringify
const finalResultStr = JSON.stringify(finalResult, null, 2);

console.log(finalResultStr);

Output Result #

Running this code will give you the merged array (as a formatted string):

[
  {
    "STUDENT_ID": "ST001",
    "MAJOR": [
      "SCIENCE"
    ],
    "STATUS": "1"
  },
  {
    "STUDENT_ID": "ST002",
    "MAJOR": [
      "SCIENCE",
      "HISTORY",
      "MATH"
    ],
    "STATUS": "1"
  },
  {
    "STUDENT_ID": "ST003",
    "MAJOR": [
      "HISTORY"
    ],
    "STATUS": "2"
  }
]

Notes #

• If you expect STATUS values might differ for the same STUDENT_ID, you can adjust the logic: for example, store all statuses in an array, or keep the latest one instead of showing a warning.
• The JSON.stringify step is optional if you just need the JavaScript array for further processing.

内容的提问来源于stack exchange，提问作者ashura91