Mongoose immutable fields plugin

Immutable property guards modifications on a field after document creation.

Mongoose immutable fields plugin was born when I had hard time trying to guard a field from modifications after document creation. I could not find something, which does that for me (maybe the mongoose concept in my head is wrong), but I had need of some way to protect my fields (from developers - myself included).

Operations-Guard

The plugin guards fields modification for following operations :

• re-save
• update
• updateOne
• updateMany
• findAndUpdate

Usage

Note! Immutable-plugin is tested only for below types of fields. The behavior of other types is unknown

| object | array | number | string | | ------ | :---: | :----: | -----: |

1. Simple Field Schema

let SimpleFieldSchema = new Schema({
    id: Schema.Types.ObjectId,
    simpleFieldA: {
      type: String,
      immutable: true
    },
    simpleFieldB: Number
});

SimpleFieldSchema.plugin(require('mongoose-immutable-plugin'));

2. Nested Field Schema

let NestedFieldSchema = new Schema({
  id: Schema.Types.ObjectId,
  levelA: {
    levelB: {
      levelC1: {
        type: String,
        immutable: true
      },
      levelC2: String
  	}
  }
});

NestedFieldSchema.plugin(require('mongoose-immutable-plugin'));

3. Array Field Schema

Note! Array-type field can be immutable, but the plugin will be triggered on array-level, not for array's items properties. That means if you have for example an array of objects and mark an object(array item) property as immutable, plugin wont handle that.

If you mark an array as immutable one, before db update, the whole array will be removed with all modifications on it

let ArrayFieldSchema = new Schema({
  id: Schema.Types.ObjectId,
  arr: {
    immutable: true
    type: [
    	{ item: String }
    ]
  }
});

ArrayFieldSchema.plugin(require('mongoose-immutable-plugin'));

4. Mixed Schema

let MixedImmutabilitySchema = new Schema({
    id: Schema.Types.ObjectId,
    parentA: {
        arr: {
            immutable: true,
            type: [
                { item: String }
            ]
        },
        childA: String,
        childB: {
            arr1: {
                immutable: true,
                type: [
                    { item: String }
                ]
            },
            arr2: {
                type: [
                    { item: String }
                ]
            }
        },
        childC: {
            type: String,
            immutable: true,
        }
    },
    parentB: String,
    parentC: {
        type: Number,
        immutable: true,
    }
});

MixedImmutabilitySchema.plugin(require('mongoose-immutable-plugin'));

Tests

You need to have installed and run mongodb
Run tests -> run the test file with npm run test

Limitations

• If you use re-save as a way to update a document, you will get back the document in the state before update (field will be updated although it is immutable) but if you retrieve it, it won't be

  Example :

      // You have defined someProp as immutable one
      let doc = new DOCModel({ someProp: 5 });
      let createdDOC = await doc.save();
  
      // createdDOC.someProp => 5
           
      doc.someProp = 6;
      let updatedDOC = await doc.save();
           
      // updatedDOC.someProp => 6
  
      let retrievedDOCAfterUpdate = await DOCModel.findById(doc._id);
  
      // retrievedDOCAfterUpdate.someProp => 5