删除另一个Schema MongoDB中的文档和所有引用

Question

I have a schema for Forms and another one for Documents ...

Each Document must have a reference _id of the Form that is related to, so in database I can have many Documents with the same Form._id .

I want to know how to create a DELETE function for the Forms to do the following:

• Find all Documents that have this Form._id and DELETE it all and then delete the Form itself.

Answer 1

In our application we do it like that: When a user got deleted, delete also its corrosponding Scans & Categories

const scanModel = require("./Scan");
const categoryModel = require("./Category");

const userSchema = new mongoose.Schema({
    ...
})

userSchema.pre("remove", function(next) {
  // 'this' is the user being removed. Provide callbacks here if you want
  // to be notified of the calls' result.
  scanModel.remove({ user: this._id }).exec();
  categoryModel.remove({ user: this._id }).exec();
  next();
});

Answer 2

Ok, so lets start of with some basic forms and documents in our database

db.forms.insertMany([
   { _id : 1, name : "Form 1"},
   { _id : 2, name : "Form 2"}
]);

db.documents.insertMany([
  { _id : 1, formId : 1, name : "Doc 1" },
  { _id : 2, formId : 1, name : "Doc 2" },
  { _id : 3, formId : 1, name : "Doc 3" },
  { _id : 4, formId : 2, name : "Doc 4" }
])

> db.forms.find()
{ "_id" : 1, "name" : "Form 1" }
{ "_id" : 2, "name" : "Form 2" }

> db.documents.find()
{ "_id" : 1, "formId" : 1, "name" : "Doc 1" }
{ "_id" : 2, "formId" : 1, "name" : "Doc 2" }
{ "_id" : 3, "formId" : 1, "name" : "Doc 3" }
{ "_id" : 4, "formId" : 2, "name" : "Doc 4" }

Then we can create a simple function to pass in the form id and find and delete all the documents for that form id.

function removeForm(formId){

   var ids = db.documents.find({ formId : formId}, { _id : 1 } ).map(function(doc){ return doc["_id"]; });

   db.documents.remove( { "_id" : { "$in" : ids } } );

   db.forms.remove( { "_id" : formId } );
}

Then we can call removeForm.

removeForm(1);

Then we'll see our documents and forms deleted

> db.forms.find()
{ "_id" : 2, "name" : "Form 2" }
> db.documents.find()
{ "_id" : 4, "formId" : 2, "name" : "Doc 4" }