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Phase 2 / FilterAttribute

The user interface may offer a list of filters from the DataFields. The DESDA.FilterAttribute lets the business logic dictate which DataFields are offered. It also determines which string-type DataFields are including in a multi-field search, where the user inputs a phrase and its searched against the list of DataFields.

When displaying filters, sometimes the user interface needs just the most common properties and other times it needs all of them. The AutoGeneratePriority property determines the priority of the DataField. The available priorities are Always, Standard, Advanced, Complete, and Never.

To further assist the user, filters are often built using ranges of values, such as when the user picks UnitPrice, the user can pick from $0-$99, $100-$199, and $200-up. BLD provides the DESDA.RangeEntityFilterPickerAttribute and DESDA.DateRangeEntityFilterPickerAttribute to supply the user interface with those ranges. The DESDA.RangeEntityFilterPickerAttribute is used for numbers. The DESDA.DateRangeEntityFilterPickerAttribute is used for dates and supports smart "relative date" rules.

Here are FilterAttributes associated with the Employee Entity class.

public class EmployeeMetadata
   public object BirthDate { get; set; }

   public object City { get; set; }

   public object FirstName { get; set; }

   [DESDA.DateRangeEntityFilterPicker(new PeterBlum.DES.QuickRange[] 
         PeterBlum.DES.QuickRange.NotSet, // assigned to 3 years ago
         PeterBlum.DES.QuickRange.NotSet},   // assigned to 1990s
      new string[] {
         "Label='3 years ago' StartDate-DateType='Relative' StartDate-PeriodType='Year' StartDate-PeriodOffset='-2' EndDate-DateType='Relative' EndDate-PeriodType='Year' EndDate-PeriodOffset='-2' EndDate-DayOffset='-1'",
         "Label='1990s' StartDate-ActualDate='1990-01-01' EndDate-ActualDate='1999-12-31'",
         "Label='2000s' StartDate-ActualDate='2000-01-01' EndDate-ActualDate='2009-12-31'"})]
   public object HireDate { get; set; }

   [DESDA.Filter(DESDA.AutoGeneratePriority.Always, InMultiFieldSearch=true)]
   public object HomePhone { get; set; }

   [DESDA.Filter(DESDA.AutoGeneratePriority.Always, InMultiFieldSearch=true)]
   public object LastName { get; set; }

   public object Notes { get; set; }

   public object TitleOfCourtesy { get; set; }

The Source Code Browser shows completed DataAnnotations. The FilterAttributes have been highlighted.

In the next topic, you'll learn how to identiy which DataFields should appear and their order in the user interface.

Open the Source Code Browser (C# only)
Source Code Browser
/* ------------------------------------------------
 * Describes the Entity class for: Category
 * Classes:
 *    Category - Entity class. Edit it for validation and to customize metadata at runtime
 *    CategoryMetadata - Entity Metadata class. It contains the DataAnnotations.
 *    CategoryDAO - BLD DataAccessObject format version of a Data Access Object.

 * Requires .net 4.0 and these references:
 *    System.ComponentModel.DataAnnotations
 *    PeterBlum.DES
 *    PeterBlum.DES.DataAnnotations
 * Generated: 7/8/2011 4:17:08 PM
 * ------------------------------------------------*/
using System;
using System.ComponentModel;
using System.ComponentModel.DataAnnotations;
using System.Collections.Generic;
using System.Linq;
using System.Data.Linq;
using PeterBlum.DES.DAO;
using PeterBlum.DES.DAO.Attributes;
using PeterBlum.DES.DAO.EntityDAO;
using PeterBlum.DES.DataAnnotations;

// Some members of this namespace have identical names to those in System.ComponentModel.DataAnnotations
// making it easy to switch from one to the other by adding the "DESDA." prefix
using DESDA = PeterBlum.DES.DataAnnotations;

namespace PeterBlum.WithDataAnnotations
   // --- ENTITY CLASS --------------------------------------------------
   /// <summary>
   /// Entity class. Edit it for validation and to customize metadata at runtime
   /// </summary>
   public partial class Category
/// <summary>
/// Associated with the CustomValidationAttribute on the Category.CategoryName property,
/// this uses LINQ to SQL to detect an existing Category with the same name
/// and reports it as an error.
/// </summary>
/// <remarks>
/// <para>You probably will create many of these methods. Consider using stored procedures
/// to search the database for duplicates. Write your code below to invoke the stored procedures.</para>
/// </remarks>
/// <param name="pNewName"></param>
/// <param name="pValidationContext"></param>
/// <returns></returns>
      public ValidationResult CheckForDuplicateCategoryNames(
         string pNewName, ValidationContext pValidationContext)
         BaseDAOChangeEntityActionArgs vArgs = (BaseDAOChangeEntityActionArgs)pValidationContext.GetChangeEntityActionArgs();

         ChangeEntityAction vAction = vArgs != null ? vArgs.Action : ChangeEntityAction.Update;
         if ((vAction == ChangeEntityAction.Insert) || (vAction == ChangeEntityAction.Update))
            Category vCategory = (Category)vArgs.Entity;
            int vThisCategoryID = (vAction == ChangeEntityAction.Insert) ? -1 : vCategory.CategoryID;
            NorthWindDataContext vDataContext = new NorthWindDataContext();
            System.Data.Linq.Table<Category> vTable = vDataContext.Categories;
            if (vTable.FirstOrDefault<Category>(category =>
               (String.Compare(category.CategoryName, pNewName, StringComparison.CurrentCultureIgnoreCase) == 0)
               && (category.CategoryID != vThisCategoryID)) != null)
               DESDA.EntityValidationResult vResult = new DESDA.EntityValidationResult(
                  "CheckForDuplicateCategoryNames", // this is the Source parameter. It can be anything. It is used by the BLDPageManager.UpdateErrorMessage event. So make it useful for detecting this particular error
                  "This name already exists. Choose another.",
                  typeof(Category), "CategoryName", pNewName);
               vResult.SummaryErrorMessage = "{LABEL} already exists. Choose another.";
               return vResult;

         return ValidationResult.Success;
   }  // class Category

   // --- ENTITY METADATA --------------------------------------------------
   /// <summary>
   /// Entity Metadata class.
   /// Companion to the Category Entity class that contains the DataAnnotations
   /// on properties with the same names as those in the actual Entity class.
   /// These properties do not require their types to match those in the Entity class.
   /// An Entity Metadata class allows the Entity class to be regenerated without
   /// overwriting DataAnnotations.
   /// </summary>
   [DESDA.InjectionSecurity(DetectScriptInjection=true, DetectSQLInjection=false)]  // impacts CategoryName, but not Description which has its own rules
   [DESDA.TableRestriction("Admin", DESDA.DenyAccess.None)]
   [DESDA.TableRestriction("Customer", DESDA.DenyAccess.Edit | DESDA.DenyAccess.Delete | DESDA.DenyAccess.Insert)]
   public class CategoryMetadata

      [DESDA.Filter(AutoGeneratePriority=DESDA.AutoGeneratePriority.Always, InMultiFieldSearch=true)]
      public object CategoryName { get; set; }
   /// <summary>
   /// In this example, explicitly make this a Multiline text element
   /// so it benefits from the MultilineText_Edit.ascx Field Template.
   /// Like most large textual fields, it should detect illegal hacking case.
   /// When the Peter's Input Security module is setup, the InjectionSecurityAttribute
   /// will block unwanted input.
   /// </summary>
      [DESDA.InjectionSecurity(DetectScriptInjection=true, DetectSQLInjection=true, 
      public object Description { get; set; }

      [DESDA.DbImageDataType(BadFormatErrorMessage="Bad format", ErrorMessage="Must be {EXTENSION}", SupportedFileTypes="jpg")]
      public object Picture { get; set; }

   }  // class CategoryMetadata

   // --- BLD DATAACCESSOBJECT  --------------------------------------------------
   /// <summary>
   /// BLD DataAccessObject class for the Category Entity class.
   /// It provides CRUD actions. The parent class already has default
   /// methods for Update(), Insert(), Delete() and several queries.
   /// </summary>
   /// <remarks>
   /// <para>For documentation, see the BLD DataAccessObject section of the Business Logic User's Guide.</para>
   /// </remarks>
   public class CategoryDAO : LINQtoSQLEntityDAO<Category>
      public CategoryDAO() : base(typeof(NorthWindDataContext)) { }
      public CategoryDAO(object pDataContext) : base(pDataContext) { }

   }  // class CategoryDAO