mongo group query how to keep fields

👋 Hey there! Looking to keep all the fields in a MongoDB group query? I got you covered! 🙌 In this blog post, I'll walk you through a common issue faced when using a group query in MongoDB, and provide you with easy solutions to keep all the fields you need. So let's dive in! 💪

🔍 Understanding the Problem: When performing a group query in MongoDB, the result typically only shows the key(s) specified in the arguments. But what if you want to keep all the fields in the first document of each group, just like in a MySQL query? That's where things can get a bit tricky.

🤔 The Solution: To achieve the desired result, you can combine the $first operator with the $push operator in the aggregation pipeline. Here's an example to guide you:

db.users.aggregate([
  {
    $group: {
      _id: "$name",
      age: { $first: "$age" },
      sex: { $first: "$sex" },
      province: { $first: "$province" },
      city: { $first: "$city" },
      area: { $first: "$area" },
      address: { $first: "$address" },
      count: { $sum: 1 }
    }
  }
])

🔍 Explanation: In this example, we're using the $group stage of the aggregation pipeline. We group the documents by the "name" field, and then for each group, we use the $first operator to keep the first occurrence of each field. We also use the $sum operator to count the number of documents in each group.

💡 Example: Let's see how this solution works with the provided example:

[
  {
    "name": "ddl1st",
    "age": 22,
    "sex": "纯爷们",
    "province": "BeiJing",
    "city": "BeiJing",
    "area": "ChaoYang",
    "address": "QingNianLu",
    "count": 1
  },
  {
    "name": "24k",
    "age": 220,
    "sex": "...",
    "province": "...",
    "city": "...",
    "area": "...",
    "address": "...",
    "count": 1
  }
]

📢 Call-to-Action: That's it! 🎉 Now you know how to keep all the fields in a MongoDB group query using the aggregation pipeline. Give it a try in your own projects and let me know if you have any further questions or need more examples. Keep exploring and happy coding! 💻💪