How to set limit for array size in Mongoose schema
With a small tweak to your schema setup you can add a validate option:
var peopleSchema = new Schema({
name: {
type: String,
required: true,
default: true
},
friends: {
type: [{
type: Schema.Types.ObjectId,
ref: 'peopleModel'
}],
validate: [arrayLimit, '{PATH} exceeds the limit of 10']
}
});
function arrayLimit(val) {
return val.length <= 10;
}
You can use $slice modifier at the time you push new friend id into your array https://docs.mongodb.com/manual/reference/operator/update/slice/#up._S_slice
$push: {
friends: {
$each: [id],
$slice: -10
}
}
starting from mongo 3.6 you can add validation for a collection at server end, each document inserted/updated will be validated against the validator $jsonSchema, only the valid gets inserted, validation error will be for invalid documents
db.createCollection("people", {
validator: {
$jsonSchema: {
bsonType: "object",
required: [ "name" ],
properties: {
name: {
bsonType: ["string"],
description: "must be a string"
},
friends: {
bsonType: ["array"],
items : { bsonType: ["string"] },
minItems: 0,
maxItems: 10,
description: "must be a array of string and max is 10"
}
}
}
}
});
collection
> db.people.find()
valid document
> db.people.insert({name: 'abc' , friends : ['1','2','3','4','5','6','7','8','9','10']})
WriteResult({ "nInserted" : 1 })
invalid document
> db.people.insert({name: 'def' , friends : ['1','2','3','4','5','6','7','8','9','10', '11']})
WriteResult({
"nInserted" : 0,
"writeError" : {
"code" : 121,
"errmsg" : "Document failed validation"
}
})
find
> db.people.find()
{ "_id" : ObjectId("5a9779b60546616d5377ec1c"), "name" : "abc", "friends" : [ "1", "2", "3", "4", "5", "6", "7", "8", "9", "10" ] }
>
This is my schema and array limit on assignedToId via an external function.
const mongoose = require("mongoose");
const Schema = mongoose.Schema;
const taskSchema = new Schema({
parentTask: {
trim: true,
type: Schema.Types.ObjectId,
ref: "task",
},
assignedToId: [{
trim: true,
type: Schema.Types.ObjectId,
ref: "Employees",
}],
createdBy: {
trim: true,
type: Schema.Types.ObjectId,
ref: "Employees",
required: [true, "User ID is required"]
},
createdByName: {
trim: true,
type: String,
required: [true, "Creater name is required"]
},
},
{
timestamps: true
});
// Validations for assignedTo employees' size
taskSchema.path('assignedToId').validate(function (value) {
console.log(value.length)
if (value.length > 10) {
throw new Error("Assigned person's size can't be greater than 10!");
}
});
const Tasks = mongoose.model("Tasks", taskSchema);
module.exports = Tasks;