《Asp.net2.0开发指南》－ObjectDataSource 典型应用2 绑定业务逻辑层的实现
去年在长沙，电脑送人了，在家闲着没事买了这本书《Asp.net2.0开发指南》对我这个菜鸟来说，这本书还可以，介绍了一些asp.net2.0中的新知识。个人感觉C#2.0基础部分太没必要了，有点浪费了我的MONEY。
对于业务实体这块比较感兴趣，所以仔细看了ObjectDataSource部分。尽管如此，我是即没看的很明白也没做的很明白。
定义实体类Author :没有啥问题
using System;using System.Collections.Generic;using System.Text;namespace LogicLibrary
{
public class Author
{
private string _id; private string _firstname; private string _lastname; private string _state; public Author() { } public Author(string id,string firstname,string lastname,string state) { this.ID = id; this.FirstName = firstname; this.LastName = lastname; this.State = state;
} public string ID { get { return _id; } set { _id = value; } } public string FirstName { get { return _firstname; } set { _firstname = value; } } public string LastName { get { return _lastname; } set { _lastname = value; } } public string State { get { return _state; } set { _state = value; } } }
}定义业务逻辑组件
using System;using System.Collections.Generic;using System.Text;using System.Data;namespace LogicLibrary{ public class AuthorsComponent { public AuthorsComponent() { } // public List<Author> GetAuthorsByState(string state, string sortExpression) { List<Author> authors = new List<Author>(); DataTable dt = AuthorDB.AuthorDB.GetAuthorsByState(state); foreach (DataRow row in dt.Rows) { authors.Add(new Author((string)row["id"],(string)row["lastname"],(string)row["firstname"],(string)row["state"])); } authors.Sort(new AuthorComparer(sortExpression)); return authors; } // public int UpdateAuthor(Author a) { return AuthorDB.AuthorDB.UpdateAuthor(a.ID,a.LastName,a.FirstName,a.State); } public int UpdateAuthor(string ID,string LastName,string FirstName,string State) { return AuthorDB.AuthorDB.UpdateAuthor(ID,LastName,FirstName,State); } // public List<string> GetStates() { List<string> states = new List<string>(); DataSet ds = AuthorDB.AuthorDB.GetStates(); foreach (DataRow row in ds.Tables[0].Rows) states.Add((string)row["state"]); return states; } } //自定义排序 实现IComparer接口 public class AuthorComparer : IComparer<Author> { private string _sortColumn; private bool _reverse; //构造函数 public AuthorComparer(string sortExpression) { _reverse = sortExpression.ToLowerInvariant().EndsWith(" desc"); if (_reverse) { _sortColumn = sortExpression.Substring(0, sortExpression.Length - 5); } else { _sortColumn = sortExpression; } } //实现接口的Compare方法 比较两个Author对象实例 public int Compare(Author a,Author b) { int retVal = 0; switch (_sortColumn) { case "ID": retVal = String.Compare(a.ID, b.ID, StringComparison.InvariantCultureIgnoreCase); break; case "FirstName": retVal = String.Compare(a.FirstName, b.FirstName, StringComparison.InvariantCultureIgnoreCase); break; case "LastName": retVal = String.Compare(a.LastName, b.LastName, StringComparison.InvariantCultureIgnoreCase); break; case "State": retVal = String.Compare(a.State, b.State, StringComparison.InvariantCultureIgnoreCase); break; } return (retVal*(_reverse?-1:1)); } } }using System;using System.Collections.Generic;using System.Text;using System.Data;using System.Xml;namespace AuthorDB{ public class AuthorDB { //string str = System.Configuration.ConfigurationSettings.AppSettings["xmlFile"].ToString().Trim(); public AuthorDB() { } // public static DataSet GetStates() { string str = @"C:\Documents and Settings\lzfan\My Documents\Visual Studio 2005\WebSites\ObjectDataSourceExample\App_Data\Author.xml"; DataSet ds = new DataSet(); ds.ReadXml(str,XmlReadMode.ReadSchema); return ds; } public static DataTable GetAuthorsByState(string state) { string str = @"C:\Documents and Settings\lzfan\My Documents\Visual Studio 2005\WebSites\ObjectDataSourceExample\App_Data\Author.xml"; DataSet ds = new DataSet(); ds.ReadXml(str,XmlReadMode.ReadSchema); //DataRow[] drs = ds.Tables[0].Select("state="+state.ToString().Trim()); DataView dv = new DataView(ds.Tables[0],state,null,DataViewRowState.CurrentRows); return dv.Table; } public static int UpdateAuthor(string au_id,string au_lname,string au_fname,string state) { int i = 0; return i; // } }}<body> <form id="form1" runat="server"> <div> <asp:DropDownList ID="DropDownList1" runat="server" DataSourceID="obj1" AutoPostBack="True" > </asp:DropDownList> <asp:objectdatasource id="obj1" runat="server" typename="LogicLibrary.AuthorsComponent" selectmethod="GetStates"></asp:objectdatasource> <asp:gridview id="gridview1" runat="server" datasourceid="objectdatasource2" allowpaging="true" allowsorting="true" autogeneratecolumns="false" enabletheming="true"> <columns> <asp:commandfield showeditbutton="true" canceltext="cancle" /> <asp:boundfield datafield="id" headertext="id" sortexpression="id" /> <asp:boundfield datafield="firstname" headertext="firstname" sortexpression="firstname" /> <asp:boundfield datafield="lasename" headertext="lasename" sortexpression="lasename" /> <asp:boundfield datafield="state" headertext="state" sortexpression="state" /> </columns> </asp:gridview> <asp:objectdatasource id="objectdatasource2" runat="server" typename="LogicLibrary.AuthorsComponent" dataobjecttypename="LogicLibrary.Author" selectmethod="GetAuthorsByState" updatemethod="UpdateAuthor" sortparametername="sortExpression"> <selectparameters> <asp:controlparameter controlid="DropDownList1" name="state" PropertyName="SelectedValue"/> </selectparameters> </asp:objectdatasource> </div> </form></body><?xml version="1.0" encoding="UTF-8"?><root xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns:od="urn:schemas-microsoft-com:officedata"> <xsd:schema> <xsd:element name="dataroot"> <xsd:complexType> <xsd:sequence> <xsd:element ref="Author" minOccurs="0" maxOccurs="unbounded"/> </xsd:sequence> <xsd:attribute name="generated" type="xsd:dateTime"/> </xsd:complexType> </xsd:element> <xsd:element name="Author"> <xsd:annotation> <xsd:appinfo> <od:index index-name="id" index-key="id " primary="no" unique="no" clustered="no"/> </xsd:appinfo> </xsd:annotation> <xsd:complexType> <xsd:sequence> <xsd:element name="id" minOccurs="0" od:jetType="text" od:sqlSType="nvarchar"> <xsd:simpleType> <xsd:restriction base="xsd:string"> <xsd:maxLength value="50"/> </xsd:restriction> </xsd:simpleType> </xsd:element> <xsd:element name="firstname" minOccurs="0" od:jetType="text" od:sqlSType="nvarchar"> <xsd:simpleType> <xsd:restriction base="xsd:string"> <xsd:maxLength value="50"/> </xsd:restriction> </xsd:simpleType> </xsd:element> <xsd:element name="lastname" minOccurs="0" od:jetType="text" od:sqlSType="nvarchar"> <xsd:simpleType> <xsd:restriction base="xsd:string"> <xsd:maxLength value="50"/> </xsd:restriction> </xsd:simpleType> </xsd:element> <xsd:element name="state" minOccurs="0" od:jetType="text" od:sqlSType="nvarchar"> <xsd:simpleType> <xsd:restriction base="xsd:string"> <xsd:maxLength value="50"/> </xsd:restriction> </xsd:simpleType> </xsd:element> </xsd:sequence> </xsd:complexType> </xsd:element> </xsd:schema> <dataroot xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" generated="2007-04-13T15:35:20"> <Author> <id>1</id> <firstname>123</firstname> <lastname>321</lastname> <state>China</state> </Author> <Author> <id>2</id> <firstname>456</firstname> <lastname>654</lastname> <state>USA</state> </Author> <Author> <id>3</id> <firstname>789</firstname> <lastname>987</lastname> <state>Japan</state> </Author> </dataroot></root>问题：几个组件编译都通过了，但是运行时会出现如下问题，不知道是为什么
Column 'state' does not belong to table dataroot. Source Error: Line 37: DataSet ds = AuthorDB.AuthorDB.GetStates();Line 38: foreach (DataRow row in ds.Tables[0].Rows)Line 39: states.Add((string)row["state"]);Line 40: return states; 
