Find(), GetPaged() Overload: Search by Entity

A feature I've seen in a lot of DALs and have used in the past is the ability to pass an entity instance to a search method (e.g., Find(), GetPaged()) in order to pass search parameters.  I find this approach particularly elegant, personally, and was surprised not to find it in .netTiers. I would see this being an alternative to using SqlFilterParameterCollection.

For example, if my data entity object is Product: 

    Product oProduct = new Product();
    oProduct.Name = "A%";
    oProduct.DateAdded = "2007-01-01";   

    TList<Customers> list1 = DataRepository.CustomersProvider.Find(oProduct);

A similar option, with slightly more flexibility, would be to build an [Entity]Search class that inherits from the [Entity] class but implements additional search metadata, such as:

    oProduct.Name = "A";
    oProduct.NameSearchMethod = ">";
    oProduct.DateAdded = "2007-01-01";
    oProduct.DateAddedSearchMethod = "<=";

I can see arguments for and against this.  Obviously, even with the Search class option this is a bit limited in that it can't support multiple conditions per field.  Nonetheless, I don't see it as being terribly difficult to add and it wouldn't break existing code so it would be a definite "nice to have".

Jeremy
 

Hi Jeremy,

 Have you taken a look at the [Entity]ParameterBuilder classes?  I think they provide the functionality you are looking for and are more complete than what you have listed above.

ProductsParameterBuilder pb = new ProductsParameterBuilder();
pb.AppendGreaterThan(ProductsColumn.ProductName, "A");
pb.AppendLessThanOrEqual(ProductsColumn.LastUpdate, "1/1/07");

TList<Products> list = DataRepository.ProductsProvider.Find(pb.GetParameters());

There are a whole slew of different append options and you can also control the junction operator (and, or, in).  Bobby also had a post that showed how you can effectively group parameters together with parenthesis here:

As an exampe, take the following code:

ProductsParameterBuilder pb = new ProductsParameterBuilder();
pb.AppendGreaterThan(ProductsColumn.ProductName, "A");
pb.AppendLessThanOrEqual(ProductsColumn.LastUpdate, "1/1/07");
pb.Append("AND (", ProductsColumn.ProductName, "%st%", true);
pb.Append("OR", ProductsColumn.ProductName, "%nd%", true);
pb.Append(") AND", "1", "1", false);

TList<Products> list = DataRepository.ProductsProvider.Find(pb.GetParameters());

This results in the following filter expression being built:

 (ProductName > @Param0)
 AND (LastUpdate <= @Param1)
 AND ( (UPPER(ProductName) LIKE UPPER(@Param2))
 OR (UPPER(ProductName) LIKE UPPER(@Param3))
 ) AND (1 = @Param4)