Why mongo crop an array before save? - ajax

Question

I try to save the object to a collection of mongoDb.
The object contents array of objects (name 'Children'). If the Children array length more than 20, mongo returns me empty Children array (it contents only one object with mongo's _id property).
How can I determine where is the error?
var object = {
"BrowseNodeId": "2619526011",
"Name": "Appliances",
"IsCategoryRoot": "1",
"Children": [{
"BrowseNodeId": "3737671",
"Name": "Air Conditioners"
},
// Here 30 objects {}
],
"Ancestors": {
"BrowseNodeId": "2619525011",
"Name": "Appliances"
},
};
I use $.ajax to make a post query:
$.ajax({
url: 'http://localhost:8005/api/category',
data: object,
method: 'POST',
dataType: 'application/json'
}).done((res) => {
console.log(res);
// => returns object with Children.length == 1
})
But If I use the Postman to make a post query - object comes to me with Children array length as I expect == 20.
Mongoose schema:
mongoose.model('category', new mongoose.Schema(
{
BrowseNodeId: Number,
Name: String,
Children: [{
BrowseNodeId: Number,
Name: String,
}],
Ancestors: {
BrowseNodeId: Number,
Name: String,
},
level: Number,
}
))
The implementation of http://localhost:8005/api/category:
var koa = require('koa');
var router = require('koa-router')();
var koaRestMongoose = require('koa-rest-mongoose');
var cors = require('koa-cors');
var mongoUrl = '127.0.0.1:27017/dbname';
var mongoose = require('mongoose');
mongoose.connect(mongoUrl);
var model = {
category: mongoose.model('category', new mongoose.Schema(
{
BrowseNodeId: Number,
Name: String,
Children: [{
BrowseNodeId: Number,
Name: String,
}],
Ancestors: {
BrowseNodeId: Number,
Name: String,
},
level: Number,
}
)),
item: mongoose.model('item', new mongoose.Schema(
{
BrowseNodeId: Number,
Name: String,
}
)),
}
var app = koa();
app.use(cors());
koaRestMongoose(app, router, model.category, '/api');
koaRestMongoose(app, router, model.item, '/api');
app.use(router.routes());
app.listen(8005);
I assume it may be schema issue
UPD
When I use ajax request body is:
Cat: { Name: 'Test',
'Children[0][BrowseNodeId]': '11',
'Children[1][BrowseNodeId]': '11' }
With the Postman request is:
Children: [ { BrowseNodeId: '11' }, { BrowseNodeId: '11' } ] }