当前文件： SmallBusinessStarterKit/smallbusiness_vb/App_Code/Catalog/XmlCatalogProvider.vb[6K，2009-6-12 11:54:22]，打开代码结构图

		            
  1Imports System
  2Imports System.Data
  3Imports System.Configuration
  4Imports System.Web
  5Imports System.Xml
  6Imports System.Xml.Schema
  7Imports System.IO
  8Imports System.Collections.Generic
  9
 10
 11' <summary>
 12' XML Data Layer for Items and Cateogories
 13' </summary>
 14Public Class XmlCatalogProviderClass XmlCatalogProvider
 15    Inherits CatalogProvider
 16
 17    Private _xmlFile As String
 18    Private _xsdFile As String
 19
 20
 21
 22    Public Sub New()Sub New()
 23        Dim sec As SmallBusinessDataProvidersSection = ConfigurationManager.GetSection("SmallBusinessDataProviders")
 24        Dim xmlFile As String = sec.CatalogProviders(sec.CatalogProviderName).Parameters("dataFile")
 25        Dim xsdFile As String = sec.CatalogProviders(sec.CatalogProviderName).Parameters("schemaFile")
 26
 27        _xmlFile = HttpContext.Current.Request.MapPath(("~/App_Data/" + xmlFile))
 28        _xsdFile = HttpContext.Current.Request.MapPath(("~/App_Data/schemas/" + xsdFile))
 29    End Sub 'New 
 30
 31
 32
 33    ' <summary>
 34    ' Returns child categories of a given cateogory
 35    ' If 'parentCategoryId' = null , top level categories are returned
 36    ' </summary>
 37    Public Overrides Function GetChildCategories()Function GetChildCategories(ByVal parentCategoryId As String) As List(Of Category)
 38
 39        If [String].IsNullOrEmpty(parentCategoryId) Then
 40            parentCategoryId = "NULL"
 41        End If
 42        Dim dataSet As DataSet = Util.ReadAndValidateXml(_xmlFile, _xsdFile)
 43
 44        ' tables, in order in the dataset: category | childItemId| item
 45        Dim categoryTbl As DataTable = dataSet.Tables(0)
 46        Dim list As New List(Of Category)
 47        Dim r As DataRow
 48        For Each r In categoryTbl.Rows
 49            If CStr(r("parentCategoryId")) = parentCategoryId Then ' match found
 50                If TypeOf r("id") Is DBNull Or TypeOf r("visible") Is DBNull Or TypeOf r("title") Is DBNull Then
 51                    Throw New InvalidOperationException(Messages.CategoryRequiredAttributesMissing)
 52                End If
 53                Dim curr As New Category(CStr(r("id")), [Boolean].Parse(CStr(r("visible"))), CStr(r("title")))
 54                curr.Description = Util.ReturnEmptyStringIfDbNull(r("description"))
 55                curr.ImageUrl = Util.ReturnEmptyStringIfDbNull(r("imageUrl"))
 56                curr.ImageAltText = Util.ReturnEmptyStringIfDbNull(r("imageAltText"))
 57                list.Add(curr)
 58            End If
 59        Next r
 60        Return list
 61    End Function 'New
 62
 63
 64
 65    ' <summary>
 66    ' Returns child items of a given cateogory
 67    ' Returns empty list if 'parentCategoryId' = null ,
 68    ' </summary>
 69    Public Overrides Function GetChildItems()Function GetChildItems(ByVal parentCategoryId As String) As List(Of Item)
 70
 71        Dim itemList As New List(Of Item)
 72
 73        If [String].IsNullOrEmpty(parentCategoryId) Then
 74            Return itemList
 75        End If
 76        Dim dataSet As DataSet = Util.ReadAndValidateXml(_xmlFile, _xsdFile)
 77
 78        ' find index correspondig to parentCategorId
 79        Dim categoryTbl As DataTable = dataSet.Tables(0)
 80        Dim index As Integer = -1
 81        Dim counter As Integer = 0
 82        Dim r As DataRow
 83        For Each r In categoryTbl.Rows
 84            If CStr(r("id")) = parentCategoryId Then
 85                index = counter
 86                Exit For
 87            End If
 88            counter += 1
 89        Next r
 90
 91        ' populate the list of child items ids and then construct Item objects
 92        Dim categorizationTbl As DataTable = dataSet.Tables(1)
 93        Dim childItemIds As New List(Of String)
 94
 95
 96        For Each r In categorizationTbl.Rows
 97            If CInt(r("category_Id")) = index Then
 98                childItemIds.Add(CStr(r("childItemId_Text")))
 99            End If
100        Next r
101
102        Dim itemsTbl As DataTable = dataSet.Tables(2)
103        Dim curr As Item
104
105        For Each r In itemsTbl.Rows
106            If childItemIds.Contains(CStr(r("id"))) Then
107                If TypeOf r("id") Is DBNull Or TypeOf r("visible") Is DBNull Or TypeOf r("title") Is DBNull Then
108                    Throw New InvalidOperationException(Messages.ItemRequiredAttributesMissing)
109                End If
110                curr = New Item(CStr(r("id")), [Boolean].Parse(CStr(r("visible"))), CStr(r("title")))
111                curr.Description = Util.ReturnEmptyStringIfDbNull(r("description"))
112                curr.Price = Util.ReturnEmptyStringIfDbNull(r("price"))
113                If (TypeOf r("inStock") Is DBNull) Then
114                    curr.InStock = True
115                Else
116                    curr.InStock = r("inStock")
117                End If
118                curr.ImageUrl = Util.ReturnEmptyStringIfDbNull(r("imageUrl"))
119                curr.ImageAltText = Util.ReturnEmptyStringIfDbNull(r("imageAltText"))
120                itemList.Add(curr)
121            End If
122        Next r
123        Return itemList
124    End Function 'New
125
126    '/<summary>
127    '/ Returns item having the id 'itemId'
128    '/</summary>
129    Public Overrides Function GetItem()Function GetItem(ByVal itemId As String) As Item
130        If [String].IsNullOrEmpty(itemId) Then
131            Return Nothing
132        End If
133        Dim dataSet As DataSet = Util.ReadAndValidateXml(_xmlFile, _xsdFile)
134
135        Dim itemsTbl As DataTable = dataSet.Tables(2)
136        Dim curr As Item = Nothing
137        Dim r As DataRow
138        For Each r In itemsTbl.Rows
139            If TypeOf r("id") Is DBNull Then
140                Throw New InvalidOperationException(Messages.ItemRequiredAttributesMissing)
141            End If
142            If itemId = CStr(r("id")) Then
143                ' assert: r[id] is not DBNull
144                If TypeOf r("visible") Is DBNull Or TypeOf r("title") Is DBNull Then
145                    Throw New InvalidOperationException(Messages.ItemRequiredAttributesMissing)
146                End If
147                curr = New Item(CStr(r("id")), [Boolean].Parse(CStr(r("visible"))), CStr(r("title")))
148                curr.Description = Util.ReturnEmptyStringIfDbNull(r("description"))
149                curr.Price = Util.ReturnEmptyStringIfDbNull(r("price"))
150                If (TypeOf r("inStock") Is DBNull) Then
151                    curr.InStock = True
152                Else
153                    curr.InStock = r("inStock")
154                End If
155                curr.ImageUrl = Util.ReturnEmptyStringIfDbNull(r("imageUrl"))
156                curr.ImageAltText = Util.ReturnEmptyStringIfDbNull(r("imageAltText"))
157            End If
158        Next r
159        Return curr
160    End Function 'GetItem
161
162
163
164
165End Class 'XmlCatalogProvider