您可以尝试使用findOneAndUpdate函数
参见https://sparkbyexamples.com/mongodb/mongodb-insert-if-not-exists/?amp=1

db.findOneAndUpdate(
   { key:1 },
   { $setOnInsert: { key: 1,name:”abc”,age: 20 } }, 
   { upsert: true, returnOriginal: false }
)

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如果该字段不存在，$set将添加一个具有指定值的新字段
doccumentation

db.collection.updateOne(
  { "key": 1 }, 
  { $set: { "name": "abc", "age": 20 } }, // The update operation using $set to update "name" and set "age" to 20
  { upsert: true } // Optional: Set to true to insert a new document if no matching document is found
);

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