How to use the objection.Model.raw function in objection

$beforeInsert () {
        this.created_on  = Model.raw('NOW()');
        this.modified_on = Model.raw('NOW()');

        // Default for meta
        if (typeof this.meta === 'undefined') {
            this.meta = {};
        }
    }

$beforeInsert (queryContext) {
        this.created_on  = Model.raw('NOW()');
        this.modified_on = Model.raw('NOW()');

        // Default for meta
        if (typeof this.meta === 'undefined') {
            this.meta = {};
        }

        return encryptPassword.apply(this, queryContext);
    }

$beforeInsert () {
        this.created_on  = Model.raw('NOW()');
        this.modified_on = Model.raw('NOW()');

        // Default for roles
        if (typeof this.roles === 'undefined') {
            this.roles = [];
        }
    }

$beforeInsert (queryContext) {
        this.created_on  = Model.raw('NOW()');
        this.modified_on = Model.raw('NOW()');

        // Default for meta
        if (typeof this.meta === 'undefined') {
            this.meta = {};
        }

        return encryptPassword.apply(this, queryContext);
    }

$beforeInsert () {
        this.created_on  = Model.raw('NOW()');
        this.modified_on = Model.raw('NOW()');

        // Default for expires_on
        if (typeof this.expires_on === 'undefined') {
            this.expires_on = Model.raw('NOW()');
        }

        // Default for domain_names
        if (typeof this.domain_names === 'undefined') {
            this.domain_names = [];
        }

        // Default for meta
        if (typeof this.meta === 'undefined') {
            this.meta = {};
        }

$beforeInsert () {
        this.created_on  = Model.raw('NOW()');
        this.modified_on = Model.raw('NOW()');

        // Default for meta
        if (typeof this.meta === 'undefined') {
            this.meta = {};
        }
    }

$beforeInsert () {
        this.created_on  = Model.raw('NOW()');
        this.modified_on = Model.raw('NOW()');

        // Default for expires_on
        if (typeof this.expires_on === 'undefined') {
            this.expires_on = Model.raw('NOW()');
        }

        // Default for domain_names
        if (typeof this.domain_names === 'undefined') {
            this.domain_names = [];
        }

        // Default for meta
        if (typeof this.meta === 'undefined') {
            this.meta = {};
        }

$beforeUpdate () {
        this.modified_on = Model.raw('NOW()');
    }

$beforeUpdate (queryContext) {
        this.modified_on = Model.raw('NOW()');
        return encryptPassword.apply(this, queryContext);
    }

$beforeUpdate () {
        this.modified_on = Model.raw('NOW()');
    }