Express-Validator Check array of Subdocuments

This is my Schema:

const InvoiceSchema = new Schema({
name: { type: String, required: true },
description: { type: String },

items: [{
    name: { type: String, required: true },
    rate: { type: Number, required: true },
    quantity: { type: Number, required:true, default: 1 },
    amount: { type: Number }
}]});

I want to know how to use Express-validator to check items elements?

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