Cant push array item that has .path() getter?

[Xpucmoc-Bockpec]

I have model

ExcursionModel.js

const mongoose = require("mongoose");


const schema = new mongoose.Schema({
  images: {
    preview: String,
    background: String,
    gallery: [{
        preview: String,
        original: String
    }]
  }
});

const UPLOADS_BASE_URL = "http://example.com/";

schema.path("images.preview").get(preview => UPLOADS_BASE_URL + preview);
schema.path("images.background").get(background => UPLOADS_BASE_URL + background);
schema.path("images.gallery").get(gallery => gallery.map(photo => {
  return {
    id: photo._id,
    preview: UPLOADS_BASE_URL + photo.preview,
    original: UPLOADS_BASE_URL + photo.original
  }
}));


mongoose.model("Excursion", schema, "gh6637");

When i trying to add new images.gallery items by .push() method there is nothing changes in array
But when i modify images.preview or images.background everything works correctly
Once i remove path getters, things getting normal

index.js

const mongoose = require("mongoose");
const ExcursionModel = require("./ExcursionModel");
const Excursion = mongoose.model("Excursion");


const settings = {
  ip: "127.0.0.1",
  port: 27017,
  database: "database",
  username: "username",
  password: "password"
};

mongoose.connect(`mongodb://${settings.username}:${settings.password}@${settings.ip}:${settings.port}/${settings.database}`).then(() => {

  return Excursion.findOne()
    .then(excursion => {
      // just key, it works properly in any cases
      e.images.background = "new value";
			
      e.images.gallery.push({
        preview: "some string",
        original: "some another string"
      });

      // there is no new array item, but if i remove path getters this will work properly
      console.log(e.images); 
  });
})
.catch(console.log);

thanks in advance

Im using mongoose 5.1.7 & node 10.5.0

[lineus]

@zhepa I'll take a look at this ASAP. In the meantime, you can add if (!gallery) { return undefined; } to your images.gallery getter. Here is an example:

6637.js

#!/usr/bin/env node
'use strict';

const mongoose = require('mongoose');
mongoose.connect('mongodb://localhost/gh-6637');
const conn = mongoose.connection;
const Schema = mongoose.Schema;

const schema = new Schema({
  images: {
    preview: String,
    background: String,
    gallery: {
      type: [{
        preview: String,
        original: String
      }]
    }
  }
});

const UPLOADS_BASE_URL = 'http://example.com/';

schema.path('images.preview').get(preview => UPLOADS_BASE_URL + preview);
schema.path('images.background').get(background => UPLOADS_BASE_URL + background);
schema.path('images.gallery').get(gallery => {
  if (!gallery) { return undefined; }
  return gallery.map(photo => {
    return {
      id: photo._id,
      preview: UPLOADS_BASE_URL + photo.preview,
      original: UPLOADS_BASE_URL + photo.original
    };
  });
});


const Test = mongoose.model('Excursion', schema, 'gh6637');

const test = new Test({
  images: {
    preview: 'preview.jpg',
    background: 'background.png',
    gallery: [
      { preview: 'preview1', original: 'original1' },
      { preview: 'preview2', original: 'original2' },
      { preview: 'preview3', original: 'original3' }
    ]
  }
});

async function run() {
  await conn.dropDatabase();
  await test.save();
  let doc = await Test.findOne();
  console.log(doc.images.preview);
  console.log(test.images.gallery);
  return conn.close();
}

run();

Output:

issues: ./6637.js
http://example.com/preview.jpg
CoreMongooseArray [
  { id: 5b376106b0173915eda5387d,
    preview: 'http://example.com/preview1',
    original: 'http://example.com/original1' },
  { id: 5b376106b0173915eda5387c,
    preview: 'http://example.com/preview2',
    original: 'http://example.com/original2' },
  { id: 5b376106b0173915eda5387b,
    preview: 'http://example.com/preview3',
    original: 'http://example.com/original3' } ]
issues:

[Xpucmoc-Bockpec]

@lineus try to

test.images.gallery.push({ preview: 'preview4', original: 'original4' });
console.log(test.images.gallery);

there is no problem with empty array i guess

[lineus]

@zhepa in the process of adapting your example for this, when I would create a model instance the code would fail even before the save. Once I got that to work, I neglected to test .push(). I'll look into this further. Thanks!

[lineus]

I've been playing around with this some. Here's a minimal repro script:

6637.js

#!/usr/bin/env node
'use strict';

const mongoose = require('mongoose');
mongoose.connect('mongodb://localhost:27017/gh6637', { useNewUrlParser: true });
const conn = mongoose.connection;
const Schema = mongoose.Schema;

const schema = new Schema({
  nested: {
    arr: [{ key: String }]
  }
});

schema.path('nested.arr').get(function(v) {
  return v.map(el => {
    return {
      key: 'foobar' + el.key,
    };
  });
});

const Test = mongoose.model('test', schema);

const test = new Test;

test.nested.arr.push({ key: 'value' });
test.nested.arr.push({ key: 'value2' });

async function run() {
  await conn.dropDatabase();
  await test.save();
  let doc = await Test.findOne();
  console.log(doc.nested.arr);
  return conn.close();
}

run();

Output:

issues: ./6637.js
CoreMongooseArray []
issues:

[lineus]

@zhepa while this is getting sorted out, here are a couple of possible ways around this based on my code above:

One is a bit of a hack.

if you change the getter to:

schema.path('nested.arr').get(function(v) {
  if (v.length > 1) {
    return v.map(el => {
      return {
        key: 'foobar' + el.key,
      };
    });
  } else {
    return v;
  }
});

the output becomes:

issues: ./6637.js
CoreMongooseArray [ { key: 'foobarvalue' }, { key: 'foobarvalue2' } ]
issues:

note if the array only contains one value, getting the array will not apply the prefix.

The second is more sane

apply the getter to the subdoc schema explicitly:

#!/usr/bin/env node
'use strict';

const assert = require('assert');
const mongoose = require('mongoose');
mongoose.connect('mongodb://localhost:27017/gh6637', { useNewUrlParser: true });
const conn = mongoose.connection;
const Schema = mongoose.Schema;

const subSchema = new Schema({
  key: String
});

subSchema.path('key').get(function(v) {
  return 'foobar' + v;
});

const schema = new Schema({
  nested: {
    arr: [subSchema]
  }
});

const Test = mongoose.model('test', schema);

const test = new Test;

test.nested.arr.push({ key: 'value' });
test.nested.arr.push({ key: 'value2' });

async function run() {
  await conn.dropDatabase();
  await test.save();
  let doc = await Test.findOne();
  console.log(doc.nested.arr[0].key);
  console.log(doc.nested.arr[1].key);
  return conn.close();
}

run();

Output:

issues: ./6637.js
foobarvalue
foobarvalue2
issues:

[vkarpov15]

Upon more careful inspection, this is expected behavior. The below is how you do what you're trying to do:

const subSchema = new Schema({
  key: String
});

subSchema.path('key').get(function(v) {
  return 'foobar' + v;
});

const schema = new Schema({
  nested: {
    arr: [subSchema]
  }
});

Or:

const schema = new Schema({
  nested: {
    arr: [{ key: String }]
  }
});

schema.path('nested.arr.0.key').get(v => 'foobar' + v);

When a getter returns an object, changes to that object do not get tracked because getters are designed to not modify the underlying document, just to transform the output.