MongoDB：删除文档时如何从变频器中获取fulldocument
#mongodb #document #watch #delete

为了在删除需要启用CollMod的文档后，将完整的文档在收藏中启用。

1.下载蒙古山https://www.mongodb.com/try/download/shell

2.运行蒙古什尔（Mongoshell）并使用Connection String与Admin用户连接，如果您需要

，请创建临时管理员

3.在Mongoshell中运行以下命令 - 更改您的收藏的“ CollMod” 

db.runCommand({collMod: "ProductReview", changeStreamPreAndPostImages: {enabled: true}})

4.在您的变更流中，您可以像这样访问已删除的文档（以下代码为nodejs）

const client = new MongoClient(env.DATABASE_URL);
const database = client.db("my_database");
const reviews = database.collection("ProductReview");

// 'fullDocumentBeforeChange' is the magic here
const changeStream = reviews.watch([], { 
  fullDocument: "updateLookup", 
  fullDocumentBeforeChange: "required" 
});

changeStream.on("change", async (event) => {
  let document;

  if (event.operationType === 'delete') {
    document = event.fullDocumentBeforeChange;
  } else {
    document = event.fullDocument;
  }

  // do some stuff with the document
});

文档：
https://www.mongodb.com/docs/v6.0/reference/operator/aggregation/changeStream/

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