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Klein bapp02.tex V3 - 12/13/2007 2:57pm Page 341 Appendix B: LINQ to Entities: The ADO.NET Entity Framework foreach (SalesOrderHeader order in query.First().SalesOrderHeader) { listbox1.Items.Add(String.Format("Order Date: {0}", order.PurchaseOrderNumber)); listbox1.Items.Add(String.Format("Total: {0}",order.TotalDue.ToString())); foreach (SalesOrderDetail item in order.SalesOrderDetail) { listBox1.Items.Add(String.Format("Product: {0} " + "Quantity: {1}", item.Name.ToString(), item.OrderQty.ToString())); } } Querying the entity data model is quite easy and efficient. Working with Objects Let’s take a look at working with objects that represent entity types defined by an entity data model. The following example illustrates how to use the entity data model to update and insert data: string ln = "Kleinerman"; productSalesContext = new AdventureWorksEntities(); Contact con = productSalesContext.Contact.Where("it.LastName = @lastname", new ObjectParameter("lastname", ln)).First(); con.EmailAddress = ""; con.EmailPromotion = 1; Contact newcon = new Contact(); newcon.EmailAddress = "asdf"; newcon.EmailPromotion = 1; newcon.FirstName = "Scott"; newcon.LastName = "Klein"; newcon.MiddleName = "L"; newcon.NameStyle = false; newcon.PasswordHash = "asdf"; newcon.PasswordSalt = "adsf"; newcon.Phone = "555-555-5555"; newcon.Suffix = "Mr."; newcon.Title = "Geek"; productSalesContext.SaveChanges(); As you saw earlier, you can also bind objects to controls, like this: ObjectQuery < Contact > salesPerson = productSalesContext.Contact.Where ("it.ContactID < 5000").OrderBy("it.LastName"); this.cbosalesPerson.DataSource = salesPerson.Include("SalesOrderHeader 341 Klein bapp02.tex V3 - 12/13/2007 2:57pm Page 342 Appendix B: LINQ to Entities: The ADO.NET Entity Framework .SalesOrderDetail"); this.cbosalesPerson.DisplayMember = "LastName"; A best practice is to detach objects from the ObjecContext when they are no longer needed. Object Services lets you accomplish this via the Detach method. This decreases the amount of memory being used. Object Services, implemented via the System.Data.Objects and System.Data.Objects.DataClasses namespaces, is a component of the .NET Entity Framework that enables you to perform CRUD operations that are expressed as strongly typed CLR objects. These objects are instances of entity types. Supporting both LINQ and Entity SQL queries, Object Services lets you query against defined types as well as track changes and bind objects to controls. productSalesContext.Detach(Contact.SalesOrderHeader); Another good practice is to manage concurrency conflicts in an object context. Making changes back to the database could cause conflicts, so those need to be handled. In the following example, the SaveChanges() method is called to save any changes back to the database. If there are any conflicts, they are caught, the object context is refreshed, and SaveChanges() reapplied. try { //make changes then save them productSalesContext.SaveChanges(); } catch (OptimisticConcurrencyException oce) { productSalesContext.Refresh(RefreshMode.ClientWins, Contact); productSalesContext.SaveChanges(); } Hopefully, you can see that working with objects is just as simple as working with LINQ to SQL. Entity Data Model Generator The Entity Data Model Generator tool is one of the options available to the developer for generating the entity data model. It is a command-line tool that provides the following functionality: ❑ Create .csdl , .ssdl ,and .msl files that are used by the entity data model. ❑ Validate existing models. ❑ Generate source code files containing object classes generated from a .csdl file. ❑ Generate source code files containing generated views from the .ssdl , .csdl ,and .msl files. The Entity Data Model Generator tool is located in \ Windows \ Microsoft.NET \ Framework \ v3.5 . Its general syntax is: EdmGen /mode:choice [options] The following table lists the available modes for the EdmGen tool. You must specify one of them. 342 Klein bapp02.tex V3 - 12/13/2007 2:57pm Page 343 Appendix B: LINQ to Entities: The ADO.NET Entity Framework Mode Description ValidateArtifacts Validates the .cdsl , .ssdl ,and .msl files. Requires at least one /inssdl or /incsdl argument. If /inmsl is specified, the /inssdl and /incsdl arguments are also required. FullGeneration Generates .cdsl , .ssdl ,and .msl , object layer and view files. Updates the database connection information in the /connectionstring option. Requires a /connectionstring argument and either a /p argument or /outssdl , /outcsdl , /outmsdl , /outobjectlayer , /outviews ,and /entitycontainer arguments. FromSSDLGeneration Generates .cdsl ,and .msl ,files.Requiresthe /inssdl argument and either a /p argument or /outcsdl , /outmsl , /outobjectlayer , / outviews ,and /entitycontainer arguments. EntityClassGeneration Creates a source code file that contains generated classes from the .csdl file. Requires the /incsdl argument and either a /p or /outobjectlayer argument. ViewGeneration Creates a source code file containing views generated from the .ssdl , .csdl ,and .msl files. Requires the /inssdl , /incsdl , /inmsl ,and either the /p or /outviews arguments. Along with the modes, you can specify one or more of the following options. Option Description /p[roject]: String value that specifies the object name. /prov[ider]: String value that specifies the name of the ADO.NET data provider. The default is System.Data.Sqlclient (the .NET Framework Data Provider for SQL Server). /c[onnection]: String value that specifies the string used to connect to the data source. /incsdl: Specifies the .csdl file or a directory where the .csdl files are located. Argument can be specified multiple times. /refcsdl: Specifies additional .csdl files used to resolve .csdl source file references specified by the /incsdl option. /inmsl: Specifies the .msl file or a directory where the .msl files are located. Argument can be specified multiple times. /inssdl: Specifies the .ssdl file or a directory where the .ssdl file is located. /outcsdl: Specifies the name of the .csdl filetobecreated. /outmsl: Specifies the name of the .msl file to be created. /outssdl: Specifies the name of the .ssdl filetobecreated. /outobjectlayer: Specifies the name of the source code file containing the generated objects fro the .csdl file. 343 Klein bapp02.tex V3 - 12/13/2007 2:57pm Page 344 Appendix B: LINQ to Entities: The ADO.NET Entity Framework Option Description /outviews: Specifies the name of the source code file containing the generated views. /language: Specifies the language for the generated source code files. Options are VB and C#. Default is C#. /namespace: Specifies the namespace to use and set in the .csdl file when running in FullGeneration or FromSSDLGeneration mode. Not used in the EntityClassGeneration mode. /entitycontainer: Specifies the name to apply to the < EntityContainer > element in the EDM file. /nologo Hides the copyright message. /help Displays command syntax and tool options. The following examples show how the EdmGen tool can be used. The first example uses the FullGeneration mode to generate all necessary files: edmgen /mode:fullgeneration /c:"Data Source=AvalonServer;Initial Catalog=AdventureWorks; Integrated Security=SSPI" /p:LINQProject In this example, a C# object source code file is created from the .csdl : edmgen /mode:entityclassgeneration /incsdl:c: \ wrox \ Appendix \ LINQ \ AdventureWorksModel.csdl /outobjectlayer: c: \ wrox \ Appendix \ LINQ \ AdventureWorksModel.cs /language:csharp The ADO.NET Entity Framework clearly helps you work with relational databases as well as model entities and relationships. 344 Klein bapp03.tex V3 - 12/13/2007 2:59pm Page 345 LINQ to XSD Any programming language that supports the .NET Framework will support LINQ. LINQ to XML is LINQ-enabled, meaning that you have access to all of the functionality of LINQ such as the standard query operators and the LINQ programming interface. Because of the integration into the .NET Framework, LINQ to XML can take advantage of functionality the .NET Framework provides, such as compile-time checking, strong typing, and debugging. LINQ to XML makes working with XML much easier by providing a simple way to work directly with methods and properties, by programming against XML tree components such as elements and attributes, but in an untyped manner. This is where LINQ to XSD comes in. LINQ to XSD lets you work with typed XML. Although LINQ to XSD is in its early stages, it’d be a shame not to include it in this book. It will probably change somewhat, but the purpose of this appendix is to provide you with an introduction to LINQ to XSD and show you some of its capabilities. This is a cool technology and makes working with XML a pleasure. LINQ to XSD has been scheduled to release after the release of Visual Studio 2008. At the time of this writing the current release of LINQ to XSD is the LINQ to XSD Preview 0.2 that works with Beta 1 of Orcas. To work with the examples in this appendix, you need to install Beta 1 of Visual Studio codenamed Orcas. LINQ to XSD Overview LINQ to XSD is a new technology aimed at enhancing the great LINQ to XML technology by providing .NET developers support for typed XML programming. For example, in typical LINQ to XML programming, you would work with an XML tree as follows: var total = (from item in SalesOrderHeader.Elements("Item") select (double)item.Element("UnitPrice") * (int)item.Element("OrderQuantity") ).Sum(); Klein bapp03.tex V3 - 12/13/2007 2:59pm Page 346 Appendix C: LINQ to XSD In this example, the developer is working with untyped XML, accessing the elements and attributes of the XML directly. However, LINQ to XSD lets you work with typed XML, like this: var total = (from item in SalesOrderHeader.Item select item.UnitPrice * item.OrderQuantity ).Sum(); Working with typed XML is made possible by XML schemas that are mapped automatically to defined object models. Through this mapping XML data can be manipulated just like other object-oriented models. The result is that you are working directly with classes that can enforce validation through the use of the schema, plus you are working with XML objects generated from the XML schemas that provide a much more efficient XML development platform. The benefit of working with typed XML is that it makes working with XML-related programming tasks much easier and makes for much more efficient code. Installing LINQ to XSD For now, LINQ to XSD is not installed when you install any beta of Visual Studio. It is a completely separate install and is currently found at the following location: http://www.microsoft.com/downloads/details.aspx?FamilyID=e9c23715 -9e71-47a7-b4db-363c2a68fab4&DisplayLang=en At a mere 1.6 megabytes, it’s a quick download. The install is simple. At the Welcome screen, click Next. On the License Agreement screen, select the I Agree option to continue with the installation, then click the Next button. The final screen of the installation wizard lets you know that the installer is ready to install LINQ to XSD. Click Next to begin the install. Once the installation is complete, you’ll notice a new Start menu option called LINQ to XSD Preview. You can tell that Microsoft is serious about this technology because not only does the LINQ to XSD installation install the necessary support files for LINQ to XSD, but it also installs several support documents along with a couple of great LINQ to XSD Visual Studio example projects. How cool is that? LINQ to XSD Example The easiest way to get a feel for LINQ to XSD and to understand what it can do is to tackle an example. You’re going to need Beta 1 as stated earlier, but before you fire up Visual Studio, a little prep work needs to be done. In the Wrox directory on your local hard drive, create a folder called AppendixC. Next, open your favorite text editor and enter the following XML. Save the file as Orders.xml. The data that this XML uses comes from the SalesOrderDetail table in the AdventureWorks database. Obviously it is not all the records from that table, but only a small subset of orders from a specific customer. < Order > < OrderDetail > < CustID > 676 < /CustID > 346 Klein bapp03.tex V3 - 12/13/2007 2:59pm Page 347 Appendix C: LINQ to XSD < OrderID > 43659 < /OrderID > < Item > < ProductID > 709 < /ProductID > < UnitPrice > 5.70 < /UnitPrice > < OrderQuantity > 6 < /OrderQuantity > < /Item > < Item > < ProductID > 711 < /ProductID > < UnitPrice > 20.18 < /UnitPrice > < OrderQuantity > 4 < /OrderQuantity > < /Item > < Item > < ProductID > 712 < /ProductID > < UnitPrice > 5.18 < /UnitPrice > < OrderQuantity > 2 < /OrderQuantity > < /Item > < Item > < ProductID > 714 < /ProductID > < UnitPrice > 28.84 < /UnitPrice > < OrderQuantity > 3 < /OrderQuantity > < /Item > < Item > < ProductID > 716 < /ProductID > < UnitPrice > 28.84 < /UnitPrice > < OrderQuantity > 1 < /OrderQuantity > < /Item > < Item > < ProductID > 771 < /ProductID > < UnitPrice > 2039.99 < /UnitPrice > < OrderQuantity > 1 < /OrderQuantity > < /Item > < /OrderDetail > < /Order > Once you have created the Orders.xml file, fire up Visual Studio and create a new C# Windows project. In the Project types section, expand the C# node. Select the LINQ to XSD Preview project type, and then choose the LINQ to XSD Windows Application from the list of project templates (see Figure C-1). Name the project LINQ, specifying the appropriate location in which to create the project. Click OK. Now open the Solution Explorer and expand the References node. Besides the typical LINQ reference of System.Xml.Linq , you’ll see a new reference to Microsoft.Xml.Schema.Linq , shown in Figure C-2. This namespace contains all the XML classes that provide the LINQ to XSD mapping functionality and XSD schema definition support. Next, open Form1 in design mode and drop a couple of buttons and a text box on the form. Set the Text property of button1 to Untyped , and then double-click the button to view its Click event. Enter the following code in the button1 Click event: var order = XElement.Load("C: \\ Wrox \\ AppendixC \\ Orders.xml"); var total = (from salesOrder in order.Elements("OrderDetail") from item in salesOrder.Elements("Item") 347 Klein bapp03.tex V3 - 12/13/2007 2:59pm Page 348 Appendix C: LINQ to XSD select (double)item.Element("UnitPrice") * (int)item.Element("OrderQuantity") ).Sum(); textBox1.Text = total.ToString(); Figure C-1 Figure C-2 348 Klein bapp03.tex V3 - 12/13/2007 2:59pm Page 349 Appendix C: LINQ to XSD From the Build menu, select Build Solution to ensure that the project compiles. Then run the application and click the Untyped button. The text box should be populated with the value of 2280.63, as shown in Figure C-3. Figure C-3 This example is similar to the examples you worked with in the Chapters 5 through 9 in the LINQ to XMLsection.Itusesthe Load method of the XElement method to load an XML document into memory. A LINQ query expression is then executed against the XML document, using the sum ( ) query operator to sum all the order totals. The results are the displayed in the text box. Notice that because the XML document is untyped, the use of the Elements method is needed to specify the element you’re looking for. Because no mapping taking place, you have to physically specify the element name. Wouldn’t it be nice to be able to use typed XML programming? Ah, yes, you can. First, open the Orders.xml file and add the following highlighted namespace to it: < Order xmlns="http://www.AdventureWorks.com/Orders" > < OrderDetail > < CustID > 676 < /CustID > < OrderID > 43659 < /OrderID > < Item > < ProductID > 709 < /ProductID > < UnitPrice > 5.70 < /UnitPrice > < OrderQuantity > 6 < /OrderQuantity > < /Item > < /Order > 349 Klein bapp03.tex V3 - 12/13/2007 2:59pm Page 350 Appendix C: LINQ to XSD Next, highlight the entire XML tree and copy it to the Clipboard. Go back to your Visual Studio project, and in the Solution Explorer window right-click the solution and select Add ➪ New Item from the context menu. In the Add New Item dialog, select XML File in the Templates section (see Figure C-4). Figure C-4 For the purposes of this example, you can keep the name of XMLFile1.xml. Click Add. XMLFile1.xml opens in the IDE and contains a single header line. Delete the XML that is there, and paste the XML that you copied from Orders.xml to the Clipboard. Save the new XMLFile.xml file. Next, return to Solution Explorer and add a new item, this time selecting an XML Schema template from the Add New Item dialog. When the schema opens, delete the default contents of the file, add the following XML, and save it: < xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema" targetNamespace="http://www.AdventureWorks.com/Orders" xmlns="http://www.AdventureWorks.com/Orders" elementFormDefault="qualified" > < xs:element name="Order" > < xs:complexType > < xs:sequence > < xs:element ref="OrderDetail" minOccurs="0" maxOccurs="unbounded"/ > < /xs:sequence > < /xs:complexType > < /xs:element > < xs:element name="OrderDetail" > < xs:complexType > < xs:sequence > < xs:element name="CustId" type="xs:string"/ > < xs:element ref="Item" minOccurs="0" maxOccurs="unbounded"/ > 350 [...]... GetQueryText, 219 GetTable, 221 IsAfter, 101 , 106 IsBefore, 101 , 106 Load, 101 , 106 LINQ to XSD, 355 populating XML trees from text, 130–131 MoveNext ( ), 34 Nodes, 101 , 106 NodesAfterSelf, 101 , 106 NodesBeforeSelf, 102 , 106 Parse, 102 , 106 LINQ to XSD, 355–356 manipulating XML in Visual Basic, 189–191 populating XML trees from text, 130 ReadFrom ( ), 171 Remove, 102 , 103 , 106 , 116, 304 deleting attributes,... 97, 102 104 XDocument, 97, 104 107 XElement, 12, 13, 14, 97, 98 102 MemberChangeConflict, 266 MethodInfo, 233 pluralization of, in O/R Designer, 296 Table (of TEntity), 302 TestAnnotation, 160 TransactionScope, 267, 269 XAttribute, 12, 97, 102 104 example, 13 methods, 103 XElement class v., 103 XCData, 97 XComment, 97 XContainer, 97 XDeclaration, 97–98 XDocument, 97, 104 107 methods, 106 objects in, 104 105 ... Remove (T), 225 RemoveAll, 102 , 116 RemoveAttributes, 102 RemoveNodes, 102 , 106 Replace, 113 7:53pm Page 370 bindex.tex V1 - 12/11/2007 7:53pm object(s) ReplaceAll, 102 , 113 ReplaceAttributes, 102 ReplaceNodes, 113 ReplaceWith, 113, 114 Save, 102 , 106 LINQ to XSD, 356 Select, 272 SetAttributeValue, 102 , 115 deleting attributes, 120 SetElementValue, 102 , 115 SetValue, 102 , 103 SubmitChanges, 219, 220,... 166–167 XML trees and, 167 Clone, LINQ to XSD, 356–357 Compile, 251 CopyToDataTable, 280 CreateDatabase, 219 CreateQuery, 219 CreateReader, 101 , 102 , 106 CreateWriter, 101 , 106 DataContext, 292 Decendants ( ), 134–135 370 DeleteDatabase, 219, 220 DescendantNodes, 101 , 106 DescendantNodesAndSelf, 101 Descendants, 163–164 DescendantsAndSelf, 101 , 165–166 Element, 101 , 106 ElementAt ( ), 134 Elements (... See also LINQ to SQL foreign keys, 212–215 primary keys, 210 212 relationship properties, 250 relationships, mapping, 206–207 Remove method, 102 , 103 , 106 , 116, 304 deleting attributes, 119–120 Remove (T) method, 225 RemoveAll method, 102 , 116 RemoveAttributes method, 102 RemoveNodes method, 102 , 106 repeat operator, 73 Replace method, 113 ReplaceAll method, 102 , 113 ReplaceAttributes method, 102 ReplaceNodes... ToList, 35 WriteTo, 102 XAttribute class, 103 XDocument class, 106 XElement class, 100 , 101 102 XNode class XML manipulation in LINQ to XML, 112–117 method syntax, 45–51, 275 example, 44 lambda expressions and, 44 query syntax v., 43–44 using, 45–51 MethodInfo class, 233 Min operator, 55, 67 MoveNext ( ) method, 34 MSXML, 121 LINQ to XML v., 121 multi-tier operations, LINQ to SQL, 302– 310 System.Reflection,... System.Xml .Linq, 96, 122 XML, 141–143 XNamespace class, 97, 142 NET Framework 3.5, 4, 17, 21, 30 1.0, 18 1.1, 18 3.0, 18 technologies, 18 2.0, 18 version choice for Visual Studio 2008, 20 Never value, 264 New Project dialog box, 19–20, 45 nodes, 98 Nodes method, 101 , 106 NodesAfterSelf method, 101 , 106 NodesBeforeSelf method, 102 , 106 /nologo, 344 None load option, 190 n-tier operations, LINQ to SQL, 302– 310. .. 98 102 creating XML elements, 110 111 deleting attributes, 119–120 deleting XML, 116–117 DOM v., 120–121 events, 167–171 Changed, 170–171 Changing, 168–170 features in Visual Basic.NET, 179–195 functional construction, 111, 137–139, 153–158 illustrations, 12–13 inserting XML, 113 LINQ enabled, 96, 345 loading XML, 107 109 from file, 107 from string, 107 108 from TextReader, 108 109 manipulating XML, 112–117... CreateReader method, 101 , 102 , 106 CreateWriter method, 101 , 106 CRUD operations, 209 cs file, 288 CTP build See Community Technology Preview build D data binding, LINQ to DataSets, 279–281 implicit, 281 data loading deferred, 252–253 turning off, 254–255 immediate, 252–253 data manipulation, via LINQ to SQL queries, 221–225 Data Source Configuration Wizard, 278, 305–307 data source, LINQ query, 32–33 DataAdapter... procedures, 207–208 tables, 203 mapping rules, LINQ to XSD, 354 Max operator, 55, 66–67 MemberChangeConflict class, 266 method(s) Add (T), 225 AddAnnotation, 101 , 103 , 106 , 158 Ancestors, 161–163 AncestorsAndSelf, 101 , 164–165 API class, LINQ to XSD, 354–358 Attach, 302–303 AttachAll, 304 Attribute, 101 axis, 161–167 Ancestors, 161–163 AncestorsAndSelf, 101 , 164–165 Descendants, 163–164 DescendantsAndSelf, . Page 345 LINQ to XSD Any programming language that supports the .NET Framework will support LINQ. LINQ to XML is LINQ- enabled, meaning that you have access to all of the functionality of LINQ such. typical LINQ reference of System.Xml .Linq , you’ll see a new reference to Microsoft.Xml.Schema .Linq , shown in Figure C-2. This namespace contains all the XML classes that provide the LINQ to. release of LINQ to XSD is the LINQ to XSD Preview 0.2 that works with Beta 1 of Orcas. To work with the examples in this appendix, you need to install Beta 1 of Visual Studio codenamed Orcas. LINQ