OrmLite Filters

Similar to interceptors in some heavy ORMs, Insert and Update filters get fired just before any INSERT or UPDATE operation using OrmLite's typed APIs.

This is most often used to auto-maintain Audit information on your POCO data models, e.g:

public interface IAudit 
{
    DateTime CreatedDate { get; set; }
    DateTime ModifiedDate { get; set; }
    string ModifiedBy { get; set; }
}

OrmLiteConfig.InsertFilter = (dbCmd, row) => {
    if (row is IAudit auditRow)
        auditRow.CreatedDate = auditRow.ModifiedDate = DateTime.UtcNow;
};

OrmLiteConfig.UpdateFilter = (dbCmd, row) => {
    if (row is IAudit auditRow)
        auditRow.ModifiedDate = DateTime.UtcNow;
};

Which will ensure that the CreatedDate and ModifiedDate fields are populated on every insert and update.

Validation Example​

The filters can also be used for validation where throwing an exception will prevent the operation and bubble the exception, e.g:

OrmLiteConfig.InsertFilter = OrmLiteConfig.UpdateFilter = (dbCmd, row) => {
    if (row is IAudit auditRow && auditRow.ModifiedBy == null)
        throw new ArgumentNullException("ModifiedBy");
};

try
{
    db.Insert(new AuditTable());
}
catch (ArgumentNullException) {
   //throws ArgumentNullException
}

db.Insert(new AuditTable { ModifiedBy = "Me!" }); //succeeds