In a Power Automate array Group By on 1 column and concatenate text in other column

by

Summary

This article addresses a common issue in Power Automate where users need to group an array by one column and concatenate text in another column. The problem arises when working with arrays of objects and the requirement is to aggregate data based on a specific key.

Root Cause

The root cause of this issue is the lack of a built-in group by function in Power Automate that can directly handle the concatenation of text fields. However, this can be achieved through a combination of Select and Group By operations.

Why This Happens in Real Systems

This scenario occurs in real systems when dealing with data aggregation and transformation, especially when integrating data from different sources or preparing data for reporting. The data might not always be in the desired format, requiring data transformation and aggregation.

Real-World Impact

The impact of not being able to perform such operations efficiently can lead to:

  • Inaccurate reporting due to incomplete data aggregation
  • Increased complexity in workflows, leading to maintainability issues
  • Performance issues due to inefficient data processing

Example or Code

// Sample input data
const inputData = {
  "body": {
    "name": "vAnswersArray",
    "type": "Array",
    "value": [
      { "Index": 0, "Title": "AC-01", "Answer": "test ac01 a" },
      { "Index": 1, "Title": "AC-02", "Answer": "test ac02 a" },
      { "Index": 2, "Title": "AC-03", "Answer": "test ac03 a" },
      { "Index": 3, "Title": "AC-04", "Answer": "test ac04 a" },
      { "Index": 4, "Title": "AC-01", "Answer": "test ac01 b" },
      { "Index": 5, "Title": "AC-03", "Answer": "test ac03 b" }
    ]
  }
};

// Group by Title and concatenate Answer
const groupedData = inputData.body.value.reduce((acc, current) => {
  const existing = acc.find(item => item.Title === current.Title);
  if (existing) {
    existing.Answer += `\n${current.Answer}`;
  } else {
    acc.push({ Title: current.Title, Answer: current.Answer });
  }
  return acc;
}, []);

console.log(groupedData);

How Senior Engineers Fix It

Senior engineers address this issue by:

  • Utilizing array methods like reduce() to iterate and aggregate the data
  • Employing object manipulation techniques to transform the data into the desired format
  • Optimizing the data processing steps to ensure performance efficiency

Why Juniors Miss It

Juniors might miss this solution because:

  • Lack of experience with advanced array methods and data manipulation techniques
  • Insufficient understanding of data aggregation and grouping concepts
  • Not considering performance optimization when designing data processing workflows