toMap method
Generate a map from a DonorUser object, used when writing data to the database
Implementation
Map<String, String> toMap(){
Map<String, String> map = Map<String, String>();
map['email'] = this.email;
map['fullName'] = this.fullName;
map['phoneNumber'] = this.phoneNumber;
map['donorNumber'] = this.donorNumber;
return map;
}