LINQ to XML一些基本查询

 /**/////根据元素的名称进行筛选（有命名空间）
            //XNamespace aw = "http://www.adventure-works.com";
            //XElement po = XElement.Load("PurchaseOrderInNamespace.xml");
            //IEnumerable<XElement> items =
            //    from el in po.Descendants(aw + "ProductName")
            //    select el;
            //foreach (XElement prdName in items)
            //    Console.WriteLine(prdName.Name + ":" + (string)prdName);


            /**/////链接轴方法
            //XElement purchaseOrders = XElement.Load("PurchaseOrders.xml");
            //IEnumerable<XElement> names =
            //    from el in purchaseOrders
            //        .Elements("PurchaseOrder")
            //        .Elements("Address")
            //        .Elements("Name")
            //    select el;
            //foreach (XElement e in names)
            //    Console.WriteLine(e);


            /**/////链接轴方法,有时，当可能存在或不存在间隔上级时，您希望在特定的元素深度，检索所有的元素
            //XElement root = XElement.Load("Irregular.xml");
            //IEnumerable<XElement> configParameters =
            //    root.Elements("Customer").Elements("Config").
            //    Elements("ConfigParameter");
            //foreach (XElement cp in configParameters)
            //    Console.WriteLine(cp);

            /**/////检索单个子元素
            //XElement po = XElement.Load("PurchaseOrder.xml");
            //XElement e = po.Element("DeliveryNotes");
            //Console.WriteLine(e);

            /**/////检索索性的集合
            //XElement val = new XElement("Value",
            //    new XAttribute("ID", "1243"),
            //    new XAttribute("Type", "int"),
            //    new XAttribute("ConvertableTo", "double"),
            //    "100");

            //IEnumerable<XAttribute> listOfAttributes =
            //    from att in val.Attributes()
            //    select att;
            //foreach (XAttribute a in listOfAttributes)
            //    Console.WriteLine(a);

            /**/////检索单个属性
            //XElement cust = new XElement("PhoneNumbers",
            //        new XElement("Phone",
            //            new XAttribute("type", "home"),
            //            "555-555-5555"),
            //        new XElement("Phone",
            //            new XAttribute("type", "work"),
            //            "555-555-6666")
            //    );
            //IEnumerable<XElement> elList =
            //    from el in cust.Descendants("Phone")
            //    select el;
            //foreach (XElement el in elList)
            //    Console.WriteLine((string)el.Attribute("type"));

            /**/////检索属性值
            //XElement root = new XElement("Root",
            //        new XAttribute("Attr", "abcde")
            //    );
            //Console.WriteLine(root);
            //string str = (string)root.Attribute("Attr");
            //Console.WriteLine(str);


            #endregion

            基本查询#region 基本查询
            /**/////查找具有特定属性的元素
            //XElement root = XElement.Load("PurchaseOrder.xml");
            //IEnumerable<XElement> address =
            //    from el in root.Elements("Address")
            //    where (string)el.Attribute("Type") == "Billing"
            //    select el;
            //foreach (XElement el in address)
            //    Console.WriteLine(el);

            /**/////查找具有特定子元素的元素
            //XElement root = XElement.Load("TestConfig.xml");
            //IEnumerable<XElement> tests =
            //    from el in root.Elements("Test")
            //    where (string)el.Element("CommandLine") == "Examp2.EXE"
            //    select el;
            //foreach (XElement el in tests)
            //    Console.WriteLine((string)el.Attribute("TestId"));


            //查询 XDocument 与查询 XElement
//             //Create a simple document and write it to a file
//                        File.WriteAllText("Test.xml", @"<Root>
//                            <Child1>1</Child1>
//                            <Child2>2</Child2>
//                            <Child3>3</Child3>
//                        </Root>");

            //Console.WriteLine("Querying tree loaded with XElement.Load");
            //Console.WriteLine("----");
            //XElement doc = XElement.Load("Test.xml");
            //IEnumerable<XElement> childList =
            //    from el in doc.Elements()
            //    select el;
            //foreach (XElement e in childList)
            //    Console.WriteLine(e);


            //Console.WriteLine("Querying tree loaded with XDocument.Load");
            //Console.WriteLine("----");
            //XDocument doc = XDocument.Load("Test.xml");
            //IEnumerable<XElement> childList =
            //    from el in doc.Elements()
            //    select el;
            //foreach (XElement e in childList)
            //    Console.WriteLine(e);

//            //查找具有特定元素名称的子代
//            XElement root = XElement.Parse(@"<root>
//                                                          <para>
//                                                            <r>
//                                                              <t>Some text </t>
//                                                            </r>
//                                                            <n>
//                                                              <r>
//                                                                <t>that is broken up into </t>
//                                                              </r>
//                                                            </n>
//                                                            <n>
//                                                              <r>
//                                                                <t>multiple segments.</t>
//                                                              </r>
//                                                            </n>
//                                                          </para>
//                                                        </root>");

//            IEnumerable<string> textSegs =
//                from seg in root.Descendants("t")
//                select (string)seg;

//            string str = textSegs.Aggregate(new StringBuilder(),
//                (sb, i) => sb.Append(i),
//                sp => sp.ToString()
//            );

//            Console.WriteLine(str);

//            //使用 Descendants 方法查找单个后代
//            XElement root = XElement.Parse(@"<Root>
//                          <Child1>
//                            <GrandChild1>GC1 Value</GrandChild1>
//                          </Child1>
//                          <Child2>
//                            <GrandChild2>GC2 Value</GrandChild2>
//                          </Child2>
//                          <Child3>
//                            <GrandChild3>GC3 Value</GrandChild3>
//                          </Child3>
//                          <Child4>
//                            <GrandChild4>GC4 Value</GrandChild4>
//                          </Child4>
//                        </Root>");

//            string grandChild3 = (string)
//                (from el in root.Descendants("GrandChild3")
//                 select el).First();
//            Console.WriteLine(grandChild3);


            /**/////编写使用复杂筛选的查询
            //XElement root = XElement.Load("PurchaseOrders.xml");
            //IEnumerable<XElement> purchaseOrders =
            //    from el in root.Elements("PurchaseOrder")
            //    where
            //        (from add in el.Elements("Address")
            //         where
            //             (string)add.Attribute("Type") == "Shipping" &&
            //             (string)add.Element("State") == "NY"
            //         select add)
            //        .Any()
            //    select el;
            //foreach (XElement el in purchaseOrders)
            //    Console.WriteLine((string)el.Attribute("PurchaseOrderNumber"));


//            //筛选可选元素
//            XElement root = XElement.Parse(@"<Root>
//                          <Child1>
//                            <Text>Child One Text</Text>
//                            <Type Value=""Yes""/>
//                          </Child1>
//                          <Child2>
//                            <Text>Child Two Text</Text>
//                            <Type Value=""Yes""/>
//                          </Child2>
//                          <Child3>
//                            <Text>Child Three Text</Text>
//                            <Type Value=""No""/>
//                          </Child3>
//                          <Child4>
//                            <Text>Child Four Text</Text>
//                            <Type Value=""Yes""/>
//                          </Child4>
//                          <Child5>
//                            <Text>Child Five Text</Text>
//                          </Child5>
//                        </Root>");
//            var cList =
//                from typeElement in root.Elements().Elements("Type")
//                where (string)typeElement.Attribute("Value") == "Yes"
//                select (string)typeElement.Parent.Element("Text");
//            foreach (string str in cList)
//                Console.WriteLine(str);


            /**/////对元素进行排序
            //XElement root = XElement.Load("Data.xml");
            //IEnumerable<decimal> prices =
            //    from el in root.Elements("Data")
            //    let price = (decimal)el.Element("Price")
            //    orderby price
            //    select price;
            //foreach (decimal el in prices)
            //    Console.WriteLine(el);

            /**/////对多个键上的元素进行排序
            //XElement co = XElement.Load("CustomersOrders.xml");
            //var sortedElements =
            //    from c in co.Element("Orders").Elements("Order")
            //    orderby (string)c.Element("ShipInfo").Element("ShipPostalCode"),
            //            (DateTime)c.Element("OrderDate")
            //    select new
            //    {
            //        CustomerID = (string)c.Element("CustomerID"),
            //        EmployeeID = (string)c.Element("EmployeeID"),
            //        ShipPostalCode = (string)c.Element("ShipInfo").Element("ShipPostalCode"),
            //        OrderDate = (DateTime)c.Element("OrderDate")
            //    };
            //foreach (var r in sortedElements)
            //    Console.WriteLine("CustomerID:{0} EmployeeID:{1} ShipPostalCode:{2} OrderDate:{3:d}",
            //        r.CustomerID, r.EmployeeID, r.ShipPostalCode, r.OrderDate);


            //计算中间值
            //XElement root = XElement.Load("Data.xml");
            //IEnumerable<decimal> extensions =
            //    from el in root.Elements("Data")
            //    let extension = (decimal)el.Element("Quantity") * (decimal)el.Element("Price")
            //    where extension >= 25
            //    orderby extension
            //    select extension;
            //foreach (decimal ex in extensions)
            //    Console.WriteLine(ex);


//           // 编写基于上下文查找元素的查询
//                        XElement doc = XElement.Parse(@"<Root>
//                            <p id=""1""/>
//                            <ul>abc</ul>
//                            <Child>
//                                <p id=""2""/>
//                                <notul/>
//                                <p id=""3""/>
//                                <ul>def</ul>
//                                <p id=""4""/>
//                            </Child>
//                            <Child>
//                                <p id=""5""/>
//                                <notul/>
//                                <p id=""6""/>
//                                <ul>abc</ul>
//                                <p id=""7""/>
//                            </Child>
//                        </Root>");

//                        IEnumerable<XElement> items =
//                            from e in doc.Descendants("p")
//                            let z = e.ElementsAfterSelf().FirstOrDefault()
//                            where z != null && z.Name.LocalName == "ul"
//                            select e;

//                        foreach (XElement e in items)
//                            Console.WriteLine("id = {0}", (string)e.Attribute("id"));

            //调试空查询结果集
//            XElement root = XElement.Parse(
//            @"<Root xmlns='http://www.adventure-works.com'>
//                            <Child>1</Child>
//                            <Child>2</Child>
//                            <Child>3</Child>
//                            <AnotherChild>4</AnotherChild>
//                            <AnotherChild>5</AnotherChild>
//                            <AnotherChild>6</AnotherChild>
//                        </Root>");
//            IEnumerable<XElement> c1 =
//                from el in root.Elements("Child")
//                select el;
//            Console.WriteLine("Result set follows:");
//            foreach (XElement el in c1)
//                Console.WriteLine((int)el);
//            Console.WriteLine("End of result set");


//            XElement root = XElement.Parse(
//            @"<Root xmlns='http://www.adventure-works.com'>
//                            <Child>1</Child>
//                            <Child>2</Child>
//                            <Child>3</Child>
//                            <AnotherChild>4</AnotherChild>
//                            <AnotherChild>5</AnotherChild>
//                            <AnotherChild>6</AnotherChild>
//                        </Root>");
//            XNamespace aw = "http://www.adventure-works.com";
//            IEnumerable<XElement> c1 =
//                from el in root.Elements(aw + "Child")
//                select el;
//            Console.WriteLine("Result set follows:");
//            foreach (XElement el in c1)
//                Console.WriteLine((int)el);
//            Console.WriteLine("End of result set");


            #endregion

            投影和转换#region 投影和转换
            //通过 LINQ to XML 使用字典
            //Dictionary<string, string> dict = new Dictionary<string, string>();
            //dict.Add("Child1", "Value1");
            //dict.Add("Child2", "Value2");
            //dict.Add("Child3", "Value3");
            //dict.Add("Child4", "Value4");
            //XElement root = new XElement("Root",
            //    from keyValue in dict
            //    select new XElement(keyValue.Key, keyValue.Value)
            //);
            //Console.WriteLine(root);

            //XElement root = new XElement("Root",
            //    new XElement("Child1", "Value1"),
            //    new XElement("Child2", "Value2"),
            //    new XElement("Child3", "Value3"),
            //    new XElement("Child4", "Value4")
            //);

            //Dictionary<string, string> dict = new Dictionary<string, string>();
            //foreach (XElement el in root.Elements())
            //    dict.Add(el.Name.LocalName, el.Value);
            //foreach (string str in dict.Keys)
            //    Console.WriteLine("{0}:{1}", str, dict[str]);


            /**/////转换 XML 树的形状
            //XElement co = XElement.Load("CustomersOrders.xml");
            //XElement newCustOrd =
            //    new XElement("Root",
            //        from cust in co.Element("Customers").Elements("Customer")
            //        select new XElement("Customer",
            //            cust.Attributes(),
            //            cust.Elements(),
            //            new XElement("Orders",
            //                from ord in co.Element("Orders").Elements("Order")
            //                where (string)ord.Element("CustomerID") == (string)cust.Attribute("CustomerID")
            //                select new XElement("Order",
            //                    ord.Attributes(),
            //                    ord.Element("EmployeeID"),
            //                    ord.Element("OrderDate"),
            //                    ord.Element("RequiredDate"),
            //                    ord.Element("ShipInfo")
            //                )
            //            )
            //        )
            //    );
            //Console.WriteLine(newCustOrd);


            /**/////投影匿名类型
            //XElement custOrd = XElement.Load("CustomersOrders.xml");
            //var custList =
            //    from el in custOrd.Element("Customers").Elements("Customer")
            //    select new
            //    {
            //        CustomerID = (string)el.Attribute("CustomerID"),
            //        CompanyName = (string)el.Element("CompanyName"),
            //        ContactName = (string)el.Element("ContactName")
            //    };
            //foreach (var cust in custList)
            //    Console.WriteLine("{0}:{1}:{2}", cust.CustomerID, cust.CompanyName, cust.ContactName);


            /**/////从 XML 生成文本文件
            //XElement custOrd = XElement.Load("CustomersOrders.xml");
            //string csv =
            //    (from el in custOrd.Element("Customers").Elements("Customer")
            //     select
            //         String.Format("{0},{1},{2},{3},{4},{5},{6},{7},{8},{9}{10}",
            //             (string)el.Attribute("CustomerID"),
            //             (string)el.Element("CompanyName"),
            //             (string)el.Element("ContactName"),
            //             (string)el.Element("ContactTitle"),
            //             (string)el.Element("Phone"),
            //             (string)el.Element("FullAddress").Element("Address"),
            //             (string)el.Element("FullAddress").Element("City"),
            //             (string)el.Element("FullAddress").Element("Region"),
            //             (string)el.Element("FullAddress").Element("PostalCode"),
            //             (string)el.Element("FullAddress").Element("Country"),
            //             Environment.NewLine
            //         )
            //    )
            //    .Aggregate(
            //        new StringBuilder(),
            //        (sb, s) => sb.Append(s),
            //        sb => sb.ToString()
            //    );
            //Console.WriteLine(csv);


//            //从 CSV 文件生成 XML

//                        // Create the text file.
//                        string csvString = @"GREAL,Great Lakes Food Market,Howard Snyder,Marketing Manager,(503) 555-7555,2732 Baker Blvd.,Eugene,OR,97403,USA
//            HUNGC,Hungry Coyote Import Store,Yoshi Latimer,Sales Representative,(503) 555-6874,City Center Plaza 516 Main St.,Elgin,OR,97827,USA
//            LAZYK,Lazy K Kountry Store,John Steel,Marketing Manager,(509) 555-7969,12 Orchestra Terrace,Walla Walla,WA,99362,USA
//            LETSS,Let's Stop N Shop,Jaime Yorres,Owner,(415) 555-5938,87 Polk St. Suite 5,San Francisco,CA,94117,USA";
//                        File.WriteAllText("cust.csv", csvString);

//                        // Read into an array of strings.
//                        string[] source = File.ReadAllLines("cust.csv");
//                        XElement cust = new XElement("Root",
//                            from str in source
//                            let fields = str.Split(',')
//                            select new XElement("Customer",
//                                new XAttribute("CustomerID", fields[0]),
//                                new XElement("CompanyName", fields[1]),
//                                new XElement("ContactName", fields[2]),
//                                new XElement("ContactTitle", fields[3]),
//                                new XElement("Phone", fields[4]),
//                                new XElement("FullAddress",
//                                    new XElement("Address", fields[5]),
//                                    new XElement("City", fields[6]),
//                                    new XElement("Region", fields[7]),
//                                    new XElement("PostalCode", fields[8]),
//                                    new XElement("Country", fields[9])
//                                )
//                            )
//                        );
//                        Console.WriteLine(cust);

            #endregion

            高级查询技术#region 高级查询技术
            /**/////联接两个集合
            //XmlSchemaSet schemas = new XmlSchemaSet();
            //schemas.Add("", "CustomersOrders.xsd");

            //Console.Write("Attempting to validate, ");
            //XDocument custOrdDoc = XDocument.Load("CustomersOrders.xml");

            //bool errors = false;
            //custOrdDoc.Validate(schemas, (o, e) =>
            //{
            //    Console.WriteLine("{0}", e.Message);
            //    errors = true;
            //});
            //Console.WriteLine("custOrdDoc {0}", errors ? "did not validate" : "validated");

            //if (!errors)
            //{
            //    // Join customers and orders, and create a new XML document with
            //    // a different shape.

            //    // The new document contains orders only for customers with a
            //    // CustomerID > 'K'
            //    XElement custOrd = custOrdDoc.Element("Root");
            //    XElement newCustOrd = new XElement("Root",
            //        from c in custOrd.Element("Customers").Elements("Customer")
            //        join o in custOrd.Element("Orders").Elements("Order")
            //                   on (string)c.Attribute("CustomerID") equals
            //                      (string)o.Element("CustomerID")
            //        where ((string)c.Attribute("CustomerID")).CompareTo("K") > 0
            //        select new XElement("Order",
            //            new XElement("CustomerID", (string)c.Attribute("CustomerID")),
            //            new XElement("CompanyName", (string)c.Element("CompanyName")),
            //            new XElement("ContactName", (string)c.Element("ContactName")),
            //            new XElement("EmployeeID", (string)o.Element("EmployeeID")),
            //            new XElement("OrderDate", (DateTime)o.Element("OrderDate"))
            //        )
            //    );
            //    Console.WriteLine(newCustOrd);
            //}


            /**/////使用分组创建层次结构
            //XElement doc = XElement.Load("Data.xml");
            //var newData =
            //    new XElement("Root",
            //        from data in doc.Elements("Data")
            //        group data by (string)data.Element("Category") into groupedData
            //        select new XElement("Group",
            //            new XAttribute("ID", groupedData.Key),
            //            from g in groupedData
            //            select new XElement("Data",
            //                g.Element("Quantity"),
            //                g.Element("Price")
            //            )
            //        )
            //    );
            //Console.WriteLine(newData);


            /**/////执行文本到 XML 的流式转换
            //StreamReader sr = new StreamReader("People.txt");
            //XStreamingElement xmlTree = new XStreamingElement("Root",
            //    from line in sr.Lines()
            //    let items = line.Split(',')
            //    where !line.StartsWith("#")
            //    select new XElement("Person",
            //               new XAttribute("ID", items[0]),
            //               new XElement("First", items[1]),
            //               new XElement("Last", items[2]),
            //               new XElement("Occupation", items[3])
            //           )
            //);
            //Console.WriteLine(xmlTree);
            //sr.Close();

            /**/////使用 XPath 查询 LINQ to XML
            //XElement root = new XElement("Root",
            //    new XElement("Child1", 1),
            //    new XElement("Child1", 2),
            //    new XElement("Child1", 3),
            //    new XElement("Child2", 4),
            //    new XElement("Child2", 5),
            //    new XElement("Child2", 6)
            //);
            //IEnumerable<XElement> list = root.XPathSelectElements("./Child2");
            //foreach (XElement el in list)
            //    Console.WriteLine(el);


            #endregion

            修改XML树#region 修改XML树
            /**/////将属性转换为元素
            //XElement root = XElement.Load("Data1.xml");
            //foreach (XAttribute att in root.Attributes())
            //{
            //    root.Add(new XElement(att.Name, (string)att));
            //}
            //root.Attributes().Remove();
            //Console.WriteLine(root);

            /**/////函数构造
            //XElement root = XElement.Load("Data1.xml");
            //XElement newTree = new XElement("Root",
            //    root.Element("Child1"),
            //    from att in root.Attributes()
            //    select new XElement(att.Name, (string)att)
            //);
            //Console.WriteLine(newTree);

            /**/////向树中添加元素
            //XElement srcTree = new XElement("Root",
            //    new XElement("Element1", 1),
            //    new XElement("Element2", 2),
            //    new XElement("Element3", 3),
            //    new XElement("Element4", 4),
            //    new XElement("Element5", 5)
            //);
            //XElement xmlTree = new XElement("Root",
            //    new XElement("Child1", 1),
            //    new XElement("Child2", 2),
            //    new XElement("Child3", 3),
            //    new XElement("Child4", 4),
            //    new XElement("Child5", 5)
            //);
            //xmlTree.Add(new XElement("NewChild", "new content"));
            //xmlTree.Add(
            //    from el in srcTree.Elements()
            //    where (int)el > 3
            //    select el
            //);
            /**///// Even though Child9 does not exist in srcTree, the following statement will not
            //// throw an exception, and nothing will be added to xmlTree.
            //xmlTree.Add(srcTree.Element("Child9"));
            //Console.WriteLine(xmlTree);


            //移除元素
//            XElement root = XElement.Parse(@"<Root>
//                            <Child1>
//                                <GrandChild1/>
//                                <GrandChild2/>
//                                <GrandChild3/>
//                            </Child1>
//                            <Child2>
//                                <GrandChild4/>
//                                <GrandChild5/>
//                                <GrandChild6/>
//                            </Child2>
//                            <Child3>
//                                <GrandChild7/>
//                                <GrandChild8/>
//                                <GrandChild9/>
//                            </Child3>
//                        </Root>");
//            root.Element("Child1").Element("GrandChild1").Remove();
//            root.Element("Child2").Elements().ToList().Remove();
//            root.Element("Child3").Elements().Remove();
//            Console.WriteLine(root);


            /**/////维护名称/值对

            //// Create an element with no content.
            //XElement root = new XElement("Root");

            /**///// Add a number of name/value pairs as attributes.
            //root.SetAttributeValue("Top", 22);
            //root.SetAttributeValue("Left", 20);
            //root.SetAttributeValue("Bottom", 122);
            //root.SetAttributeValue("Right", 300);
            //root.SetAttributeValue("DefaultColor", "Color.Red");
            //Console.WriteLine(root);

            /**///// Replace the value of Top.
            //root.SetAttributeValue("Top", 10);
            //Console.WriteLine(root);

            /**///// Remove DefaultColor.
            //root.SetAttributeValue("DefaultColor", null);
            //Console.WriteLine(root);


            /**/////元素名称/值对
            //// Create an element with no content.
            //XElement root = new XElement("Root");

            /**///// Add a number of name/value pairs as elements.
            //root.SetElementValue("Top", 22);
            //root.SetElementValue("Left", 20);
            //root.SetElementValue("Bottom", 122);
            //root.SetElementValue("Right", 300);
            //root.SetElementValue("DefaultColor", "Color.Red");
            //Console.WriteLine(root);
            //Console.WriteLine("----");

            /**///// Replace the value of Top.
            //root.SetElementValue("Top", 10);
            //Console.WriteLine(root);
            //Console.WriteLine("----");

            /**///// Remove DefaultColor.
            //root.SetElementValue("DefaultColor", null);
            //Console.WriteLine(root);
            #endregion