Mongoose encryption middleware doesn't call after aggregation

As I didn't find a better answer, I changed my code (as workaround unfortunately) to decrypt the object by myself -using the code of mongoose-encryption to decrypt after the aggregation has finished.

Most of the code was taken from GitHub (called decryptOne in my code): decryptSync function of mongoose-encryption

The 'tricky' thing was to decrypt the inner lookup value - the inner document also has the "_ct" field that should be decrypted.

let lookup: { [innerField: string]: string[]; } = {                    user: ['bio']                };this.decryptAggregation(aggregationResult, lookup);

My function gets a dictionary of the known lookup collection and its wanted fields after decryption. In that example, the other collection named users and its encrypted field is just his bio.

decryptAggregation(res: any[], innerLookup: { [innerField: string]: string[]; }) {    for (let doc of res) {        this.decryptSync(doc, innerLookup);    }}private decryptSync(doc: any, innerLookup: { [innerField: string]: string[]; }) {    this.decryptOne(doc, this.encryptedFields);    for (let innerObj in innerLookup) {        if (innerLookup.hasOwnProperty(innerObj)) {            this.decryptOne(doc[innerObj], innerLookup[innerObj]);        }    }};private decryptOne(doc: any, fields: string[]) {    let ct, ctWithIV, decipher, iv, idString, decryptedObject, decryptedObjectJSON, decipheredVal;    if (doc._ct) {        ctWithIV = doc._ct.hasOwnProperty('buffer') ? doc._ct.buffer : doc._ct;        iv = ctWithIV.slice(this.VERSION_LENGTH, this.VERSION_LENGTH + this.IV_LENGTH);        ct = ctWithIV.slice(this.VERSION_LENGTH + this.IV_LENGTH, ctWithIV.length);        decipher = crypto.createDecipheriv(this.ENCRYPTION_ALGORITHM, this.encryptionKey, iv);        try {            decryptedObjectJSON = decipher.update(ct, undefined, 'utf8') + decipher.final('utf8');            decryptedObject = JSON.parse(decryptedObjectJSON);        } catch (err) {            if (doc._id) {                idString = doc._id.toString();            } else {                idString = 'unknown';            }            throw new Error('Error parsing JSON during decrypt of ' + idString + ': ' + err);        }        fields.forEach((field) => {            decipheredVal = mpath.get(field, decryptedObject);            //JSON.parse returns {type: "Buffer", data: Buffer} for Buffers            //https://nodejs.org/api/buffer.html#buffer_buf_tojson            if (_.isObject(decipheredVal) && decipheredVal.type === "Buffer") {                this.setFieldValue(doc, field, decipheredVal.data);            } else {                this.setFieldValue(doc, field, decipheredVal);            }        });        doc._ct = undefined;        doc._ac = undefined;    }}

After those function I got my wanted object fully decrypted, the last thing to do was to project the wanted fields back to the client - with lodash.pick