How to update document using values ​​from internal array

php editor Banana brings you a practical guide on how to update a document using values ​​in an internal array. During development, we often need to get data from an array and update it into the document. This article will introduce how to use the values ​​in PHP's internal array to update documents. This method is simple and flexible, and can help us handle data update tasks more efficiently. Whether you are a beginner or an experienced developer, I hope this article can bring you some valuable knowledge and tips. Let's get started right away!

Question content

I'm stuck on something that doesn't seem complicated, maybe there's something I didn't think of or didn't see.

Have (many) documents containing arrays of objects, for example:

{
    "_id": "ox1",
    "results": [
        {
            "id": "a1",
            "somethingelse": "aa",
            "value": 1
        },
        {
            "id": "a2",
            "somethingelse": "bb",
            "value": 2
        },
        {
            "id": "a3",
            "somethingelse": "cc",
            "value": 3
        }
    ],
    "total": 0
},
{
    "_id": "ox2",
    "results": [
        {
            "id": "a1",
            "somethingelse": "aa",
            "value": 44
        },
        {
            "id": "a4",
            "somethingelse": "bb",
            "value": 4
        },
        {
            "id": "a5",
            "somethingelse": "aa",
            "value": 5
        }
    ],
    "total": 0
},
{
    "_id": "ox3",
    "results": [
        {
            "id": "a2",
            "somethingelse": "aa",
            "value": 1
        },
        {
            "id": "a3",
            "somethingelse": "aa",
            "value": 4
        },
        {
            "id": "a4",
            "somethingelse": "aa",
            "value": 5
        }
    ],
    "total": 0
}

I want an updatemany query to update all documents with "results" containing:

• "id":"a1"
• "somethingelse": "aa"

Increase its "total" by the value of "result" containing "id": "a1" and "somethingelse": "aa"

So in our example: The result for "0x1" contains "id": "a1" and "somethingelse": "aa" has a "value" of 1 -> I want its "total" to increase by 1

The result for "0x2" contains "id": "a1" and "somethingelse": "aa" has a "value" of 44 -> I want its "total" to increase by 44

"0x3" does not meet the conditions

Written in go, starting as follows:

// Here I filter only the documents meeting the condition
filter := bson.D{{
    Key: "results,
    Value: bson.D{{
        Key: "$elemMatch",
        Value: bson.D{
            {Key: "id", Value: "a1"},
            {Key: "somethingElse", Value: "aa"},
        }},
    }},
}

// This is where it gets tricky
addTotal := bson.M{
    "$set": bson.D{{
        Key: "total",
        Value: bson.D{{
            Key: "$sum",
            Value: bson.A{
                "$total",
                bson.M{ 
                    // How can I get the "value" from the right object from the array ?
                },
            },
        }},
    }},
}

is it possible? I haven't found much information about internal/embedded queries.

Solution

db.collection.updatemany(filter, update, options) The update parameter can be an update document or an aggregation pipeline ( doc).

Update documents contain only update operator expressions, which look like this:

{
   <operator1>: { <field1>: <value1>, ... },
   <operator2>: { <field2>: <value2>, ... },
   ...
}

Values ​​cannot reference fields in the document.

Although the aggregation pipeline is more advanced and can reference fields in the document. Here's one way to do it using an aggregation pipeline:

db.collection.updatemany(
  { results: { $elemmatch: { id: 'a1', somethingelse: 'aa' } } },
  [
    {
      $set: {
        total: {
          $let: {
            vars: {
              items: {
                $filter: {
                  input: '$results',
                  as: 'item',
                  cond: {
                    $and: [
                      { $eq: ['$$item.id', 'a1'] },
                      { $eq: ['$$item.somethingelse', 'aa'] },
                    ],
                  },
                },
              },
            },
            in: { $add: ['$total', { $sum: '$$items.value' }] },
          },
        },
      },
    },
  ]
);

Translated into go code:

filter := bson.M{
    "results": bson.M{
        "$elemMatch": bson.M{
            "id":            "a1",
            "somethingElse": "aa",
        },
    },
}

vars := bson.M{
    "items": bson.M{
        "$filter": bson.M{
            "input": "$results",
            "as":    "item",
            "cond": bson.M{
                "$and": bson.A{
                    bson.M{"$eq": bson.A{"$$item.id", "a1"}},
                    bson.M{"$eq": bson.A{"$$item.somethingElse", "aa"}},
                },
            },
        },
    },
}

update := bson.A{
    bson.M{
        "$set": bson.M{
            "total": bson.M{
                "$let": bson.M{
                    "vars": vars,
                    "in": bson.M{
                        "$add": bson.A{"$total", bson.M{"$sum": "$$items.value"}},
                    },
                },
            },
        },
    },
}

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