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ASP.NET Rina Zviel-Girshin Lecture 6

ASP.NET Rina Zviel-Girshin Lecture 6. Overview. DataGrid XML XSD XML and DataSet System.Xml XmlDataDocument XmlReader/XmlWriter. Display Controls. In ASP.NET exists a set of controls called “ display controls ”. These controls are

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ASP.NET Rina Zviel-Girshin Lecture 6

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  1. ASP.NET Rina Zviel-Girshin Lecture 6

  2. Overview • DataGrid • XML • XSD • XML and DataSet • System.Xml • XmlDataDocument • XmlReader/XmlWriter Rina Zviel-Girshin @Paralex

  3. Display Controls • In ASP.NET exists a set of controls called “display controls”. • These controls are • asp:Repeater (not at our course – uses Templates), • asp:DataList, • and asp:DataGrid. • The main purpose of these controls is displaying information from database tables and other external data stores to the screen. Rina Zviel-Girshin @Paralex

  4. DataGrid • The DataGrid control is the most complex and powerful of the controls used to display and maintain sets of data. • It has near a 100 properties, methods and events (more during tirgul). • The DataGrid displays a tabular data (data organized into rows and columns) from the data source or renders a table containing the SQL data. Rina Zviel-Girshin @Paralex

  5. Example Rina Zviel-Girshin @Paralex

  6. DataGrid.aspx <%@ Page Language="C#"%> <%@ Import Namespace="System.Data" %> <%@ Import Namespace="System.Data.SqlClient" %> <script runat="server"> protected void Page_Load(Object sender, EventArgs e) { SqlConnection con = new SqlConnection("Server=localhost;uid=sa; database=pubs" ); SqlDataAdapter myCommand = new SqlDataAdapter("select * from Authors", con); DataSet ds = new DataSet(); myCommand.Fill(ds, "Authors"); MyDataGrid.DataSource=ds.Tables["Authors"].DefaultView; MyDataGrid.DataBind(); } </script> Rina Zviel-Girshin @Paralex

  7. DataGrid.aspx <html><head><title>DataGrid basic example</title></head> <body> <h3><font face="Verdana">Simple Select to a DataGrid Control </font></h3> <asp:DataGrid id="MyDataGrid" runat="server" Width="700" BackColor="#ccccff" BorderColor="black" ShowFooter="false" CellPadding=3 Font-Name="Verdana" Font-Size="8pt" HeaderStyle-BackColor="#aaaadd" EnableViewState="false" /> </body> </html> Rina Zviel-Girshin @Paralex

  8. Data Source • To specify the data source for the DataGrid you have to perform the following operations: MyDataGrid.DataSource=ds.Tables["Authors"].DefaultView; MyDataGrid.DataBind(); • Or an alternative syntax is to specify both a DataSource and a DataMember from the DataSet to be used: MyDataGrid.DataSource=ds; MyDataGrid.DataMember="Authors"; MyDataGrid.DataBind(); Rina Zviel-Girshin @Paralex

  9. Columns • The DataGrid automatically displays data in a table format (grid layout) . • A first row in the DataGrid is a row of column headings. It is generated from the column names in the data source. MyDataGrid.DataSource=ds.Tables["Authors"].DefaultView; //display all the columns • The number of columns in DataGrid object equals to the number of columns in the data source. Rina Zviel-Girshin @Paralex

  10. Columns display • A DataGrid permits selections of data columns for display. • In order to select which columns to display, first specify AutoGenerateColumns="False" for the grid. • Then add a <Columns> section in the control. • In this section an <asp:BoundColumn> control is added for each column to be displayed. • This bound column binds to a column of the data source with the DataField="ColumnName" property setting. Rina Zviel-Girshin @Paralex

  11. Example <asp:DataGrid id="ProductGrid" runat="server"  AutoGenerateColumns="False"    >  <Columns>    <asp:BoundColumn      DataField=“au_fname"      HeaderText=“Author’s Family Name"      />    <asp:BoundColumn      DataField=“au_id"      HeaderText=“Author’s ID*"      ItemStyle-HorizontalAlign="Right"      FooterText="*The Id is written in XXX-XX-XXXX format"      FooterStyle-Font-Size="7pt"      />  </Columns></asp:DataGrid> Rina Zviel-Girshin @Paralex

  12. Some DataGrid properties • You can use property="value" settings to define DataGrid’slayout and styles. • Width="700“ – table’s width in pixel or % • BackColor="#ccccff" – table cells background color • BorderColor="black" – border color • BorderWidth="1"– border’s width in pixel • CellPadding=3 – amount of space (in pixels) between cell’s border and contents • CellSpacing="0” - amount of space (in pixels) between columns. Default is 0. • ShowFooter="false" – does not display table’s footer • Font-Name="Verdana" Font-Size="8pt" - defines font family • And more… Rina Zviel-Girshin @Paralex

  13. EnableViewState • EnableViewState property gets and sets a value indicating whether the server control persists its view state. • The default value is true. • That means the DataGrid stores all of its data when maintaining state and in each request all information is sent through a round trip with the form posts. • To improve the performance of your pages turn this property off. EnableViewState=“false” Rina Zviel-Girshin @Paralex

  14. XML and the DataSet • DataSet can read/write XML for its data and/or schema • You can create or modify data in a DataSet using XML file stream • You can create or modify the DataSets schema using XML schema. • XML-related DataSet methods for reading: • ReadXml: Reads an XML schema and data into the DataSet • ReadXmlSchema (xsd file): Reads an XML schema into the DataSet. • And for writing: • WriteXml, WriteXmlSchema • GetXml, GetXmlSchema Rina Zviel-Girshin @Paralex

  15. Example <%@ Page Language="C#" %> <%@ Import Namespace="System.Data" %> <script runat=server> void Page_Load(Object sender , EventArgs e) { DataSet ds = new DataSet(); ds.ReadXml(“C:\Menu.xml" ); dgrd.DataSource = ds; dgrd.DataBind(); } </script> <html><head><title>ReadXMLExample.aspx</title></head><body> <asp:DataGrid ID="dgrd" cellpadding="10" runat="server" /> </body></html> Rina Zviel-Girshin @Paralex

  16. XML • XML stands for eXtensible Markup Language. • XML is a markup language much like HTML, but its purpose is to describe data(not to display data like HTML). • XML like HTML has tags, attributes and values. • The difference is that you can define your own new tags. • You can use XML to create your own Markup Language and later use it to markup (format) your documents. Rina Zviel-Girshin @Paralex

  17. XML usage • XML is a text-based language that stores data in a way that also describes the structure of the data. • It provides a consistent format for data that can be passed easily • between applications • and across networks • and the Internet. • XML is a common data format. • Many other applications use it for configuration files. Rina Zviel-Girshin @Paralex

  18. XML data format • Visual Studio. NET uses XML as the format for storing data records, communicating, and sharing data. • XML is the native data format for ADO.NET DataSets. • The underlying fields and records in the disconnected dataset are stored as XML. • XML is optimized for sharing data across the Internet. • Office XP stores data as XML. Rina Zviel-Girshin @Paralex

  19. Some facts • Exists since 1998. • XML does not do anything. • Not owned by any one company. • An open standard. • Can represent almost any kind of data. • Supports sophisticated integrity constraints. • Simple XML documents are human-readable. • Easily converted to other formats. Rina Zviel-Girshin @Paralex

  20. XML tags/elements • XML is case-sensitive (there is a difference between upper and lowercase letters). • <Author> and <author> are two different XML tags. • You can define your own tags, called elements. • Elements naming: • Names can contain letters, numbers, and other characters, can be in any language (not advisable). • Names must not start with a number or punctuation character. • Names must not start with the letters xml (or XML or Xml or any other combination of xml). • Names cannot contain spaces. Rina Zviel-Girshin @Paralex

  21. XML File • An XML file is an ASCII text file with XML markup tags. • It has a .xml extension. • Example:myfile.xml • An XML file contains a declaration that announces that this is an XML file. • Example:<?xml version="1.0"?> • An XML file contains a content marked up with XML tags. Rina Zviel-Girshin @Paralex

  22. Example <?xml version="1.0"?> <course_info> <instructor> <iname>Rina</iname> <fname>Zviel-Girshin</fname> </instructor> <course> <cname>Web_System Development</cname> <max_st_number>20</max_st_number> <hours>3 hours a week</hours> </course> </course_info> Rina Zviel-Girshin @Paralex

  23. Inner nodes • XML inner nodes can have the same structure or can have a different structure. • Example: <instructor> and <course> • Inner nodes can have children. • Every node can have attributes. • Attribute values are quoted " or '.  • Example: <ingredient quantity="2“ units="cups">flour</ingredient> Rina Zviel-Girshin @Paralex

  24. XSD • The XML Schema language is also referred to as XML Schema Definition (XSD). • The purpose of an XML Schema is to define the legal building blocks of an XML document or to validate XML file structure. • XML Schemas are written in XML (no need to learn another new syntax and you can operate on your schemas with XML tools.). • Defines a class of documents. • Individual documents (instances) can conform to a given schema. Rina Zviel-Girshin @Paralex

  25. An XML Schema • Defines elements that can appear in a document. • Defines attributes that can appear in a document. • Defines • which elements are child elements • the order of child elements • the number of child elements • Defines whether an element is empty or can include text. • Defines data types for elements and attributes. • Defines default and fixed values for elements and attributes. Rina Zviel-Girshin @Paralex

  26. XSD file • XML Schemas are extensible to future additions • XSD Schemas support data types. • XML Schemas support namespaces. • XML Schema file has a .xsd extension. • The file defines the elements of the legal XML document. • The file starts with an <?xml version="1.0“?> prolog. • The <schema> element is the root element of every XML Schema: <xs:schema and some attributes>. Rina Zviel-Girshin @Paralex

  27. Example Student.xsd <?xml version="1.0" encoding="UTF-8"?> <xsd:schemaxmlns:xsd="http://www.w3.org/2001/XMLSchema"> <xsd:elementname=“Student"> <xsd:complexType> <xsd:sequence> <xsd:elementname="first_name" type="xsd:string"/> <xsd:elementname="last_name" type="xsd:string"/> <xsd:elementname="id" type="xsd:integer"/> </xsd:sequence> </xsd:complexType> </xsd:element> </xsd:schema> Rina Zviel-Girshin @Paralex

  28. Methods of Reading and Writing XML // Code for creating the DataSet ds and loading the // DataSet from a data source not shown. DataSet ds; … String oFile = “C:\Rina\myXmlOutput.xsd”; String iFile = “C:\Rina\myXmlInput.xsd”; // Write the DataSet’s XMLSchema to an XML Document ds.WriteXmlSchema( oFile ); // Read/Upload XML Data into the DataSet ds.ReadXml( iFile); // Write the existing Data to an XML Document ds.WriteXml( "C:\Rina\myXMLData.xml", XmlWriteMode.DiffGram); XmlWriteMode.DiffGram: writes the entire DataSet original and current values. Rina Zviel-Girshin @Paralex

  29. XML document and data table • XML files are hierarchical data structures they can be treated as database tables. • For this purpose the xml file should be limited to a three-level hierarchy: • Table name • Rows • columns Rina Zviel-Girshin @Paralex

  30. customer city phone street levi tell-aviv 039876543 namir Customers table avivi eilat 056999999 shushanim cohen haifa 048294444 prahim Example <?xml version=“1.0”?> <customers> <row> <customer>levi</customer> <city>tell-aviv</city> <phone>039876543</phone> <street>namir</street> </row> <row> <customer>avivi</customer> <city>eilat</city> <phone>056999999</phone> <street>shushanim</street> </row> … </customers> The resulting XML document: Rina Zviel-Girshin @Paralex

  31. XML with DataSets • A DataSet can be used to represent XML data. • A DataSet can represent XML data in two ways: • Load XML directly into a DataSet • ds.ReadXml(somefile); • Build an XmlDataDocument class from an existing DataSet • ds.ReadXml(somefile); • XmlDataDocument xdd= new XmlDataDocument (ds); Rina Zviel-Girshin @Paralex

  32. Reading an XML file to a DataSet <%@ Page Language="C#" %> <%@ Import Namespace="System.Data" %> <script runat=“server”> void Page_Load(Object sender , EventArgs e) { DataSet ds= new DataSet(); ds.ReadXml( MapPath( “Customers.xml" ) ); dgrd.DataSource = ds; dgrd.DataBind(); } </script> <html><head><title>ReadXmlFile.aspx</title></head> <body><asp:DataGrid ID="dgrd" cellpadding="10" runat="server" /> </body></html> Rina Zviel-Girshin @Paralex

  33. Output <?xml version="1.0"?> <customers> <row> <customer>Levi</customer> <city>Tell-Aviv</city> <phone>039876543</phone> <street>Namir</street> </row> <row> <customer> Avivi</customer> <city>Eilat</city> <phone>056999999</phone> <street>Shushanim</street> </row> <row> <customer> Cohen</customer> <city>Haifa</city> <phone>048294444</phone> <street>Prahim</street> </row> </customers> Rina Zviel-Girshin @Paralex

  34. ReadXml DataSet ds= new DataSet(); ds.ReadXml( MapPath( “Customers.xml" ) ); • A DataSet object is created. • ReadXml() method is used to read Customers.xml file from the hard drive to this ds object. • MapPath() method or more correctly Page.MapPath() method returns a physical path that a virtual path maps to. • A ds object is bound to the DataGrid and displayed. Rina Zviel-Girshin @Paralex

  35. Using a Schema • In last example a DataSet object guesses the structure of XML document. • Checked is the elements under the root can be presented as tables. • If not checks if it is a single table. • All elements presented as strings. • A best practice is to include the schema to match the xml file. Rina Zviel-Girshin @Paralex

  36. Adding a Schema • You specify a schema with an XML file in the following ways: • include the schema into the same file (schema and data) • include schema’s name in prolog section of the document • Read the schema separately using ReadXmlSchema() method of a DataSet. Rina Zviel-Girshin @Paralex

  37. Example <%@ Page Language="C#" %> <%@ Import Namespace="System.Data" %> <script runat=“server”> void Page_Load(Object sender , EventArgs e) { DataSet ds= new DataSet(); ds.ReadXmlSchema( MapPath( " Customers.xsd" ) ); ds.ReadXml( MapPath( " Customers.xml" ) ); dgrd.DataSource = ds; dgrd.DataBind(); } </script> Rina Zviel-Girshin @Paralex

  38. Example <html> <head><title>ReadSchema.aspx</title></head> <body> <asp:DataGrid ID="dgrd" cellpadding="10" runat="server" /> </body></html> Rina Zviel-Girshin @Paralex

  39. Writing an XML from a DataSet • To retrieve a string representation of Xml data GetXml() method of the DataSet can be used. • String strxml=ds.GetXml(); • This method retrieves both: the XML data and the XML schema for the DataSet. • To retrieve only a schema you can use GetXmlSchema() method. Rina Zviel-Girshin @Paralex

  40. Example <%@ Page Language="C#" %> <%@ Import Namespace="System.Data" %> <%@ Import Namespace="System.Data.SqlClient" %> <script runat=server> void Page_Load(Object sender , EventArgs e) { DataSet ds = new DataSet(); SqlConnection con = new SqlConnection("Server=localhost;uid=sa; database=pubs" ); SqlDataAdapter da = new SqlDataAdapter( "Select * From authors", con); da.Fill( ds, “DlastName" ); //name of DataMember string strXml = ds.GetXml(); Response.Write( "<pre>" + Server.HtmlEncode( strXml) + "</pre>" ); }</script> Rina Zviel-Girshin @Paralex

  41. Writing to an Xml file or a Stream • An XML representation of the DataSet can be written to a stream using: • WriteXml() method of the DataSet • WriteXmlSchema() method of the DataSet. • You can choose the output stream and the writing mode: • DiffGram – writes Xml data in such way that it can be uploaded to Sql200Server using UpdateGram method • IgnoreSchema – writes an xml data without including the schema • WriteSchema – (the default) writes both the xml data and the schema Rina Zviel-Girshin @Paralex

  42. Example <%@ Page Language="C#" %> <%@ Import Namespace="System.Data" %> <%@ Import Namespace="System.Data.SqlClient" %> <script runat=“server”> void Page_Load(Object sender , EventArgs e) { string strXml; DataSet ds = new DataSet(); SqlConnection con = new SqlConnection("Server=localhost;uid=sa; database=pubs" ); SqlDataAdapter da = new SqlDataAdapter( "Select * From authors ", con); da.Fill( ds, “DlastName" ); //name of DataMember ds.WriteXml( Response.OutputStream, XmlWriteMode.IgnoreSchema ); }</script> Writes an XML representation of the DataSet to the Response object OutputStream. Rina Zviel-Girshin @Paralex

  43. System.Xml namespace In .NET exist a group of classes that can be used to process XML data System.Xml XmlDocument XmlReader XmlWriter XmlElement XmlNodeReader XmlAttribute XmlDataDocument XmlTextReader XmlTextWriter and more Rina Zviel-Girshin @Paralex

  44. XmlDataDocument • The ADO.NET DataSet provides you with a relational representation of data (tables). • Sometimes a tree representation of the DataSet can be useful. • For hierarchical data access, you can use the XmlDataDocument class of .NET. • The DataSet can be associated with an XmlDataDocument by adding a DataSet name in the constructor of an XmlDataDocument object. • XmlDataDocument xdd = new XmlDataDocument( ds ); Rina Zviel-Girshin @Paralex

  45. Example <%@ Page Language="C#" %> <%@ import Namespace="System.Data" %> <%@ import Namespace="System.Xml" %> <script runat="server"> void Page_Load(Object sender , EventArgs e) { DataSet ds =new DataSet(); ds.ReadXml( MapPath( "Customers.xml" ) ); XmlDataDocument xdd = new XmlDataDocument( ds ); XmlNodeList nl = xdd.GetElementsByTagName("customer"); for( int i=0; i< nl.Count; i++) { lblOutput.Text += nl[i].InnerXml; } } </script> Rina Zviel-Girshin @Paralex

  46. Example <html><head> <title>XmlDataDocument.aspx</title> </head> <body> <h2>All Customers </h2> <asp:Label id="lblOutput" Runat="Server"></asp:Label> </body></html> Rina Zviel-Girshin @Paralex

  47. DataReader DataAdapter SqlData- Reader SqlData- Adapter OleDbData- Reader OleDbData- Adapter A DataSet associated with an XmlDataDocument XmlData-Document DataSet Sync XmlReader XmlText- Reader XmlNode- Reader .NET Data Provider Rina Zviel-Girshin @Paralex

  48. XmlTextReader • An XmlTextReader class provides a fast forward only access to the raw data contained in XML document. • Example: XmlTextReader xmltr; xmltr = new XmlTextReader("MyFile.xml"); while(xmltr.Read()) { …processing… } Rina Zviel-Girshin @Paralex

  49. XmlTextWriter • An XmlTextWriter class provides a fast forward only method to write data to an Xml file. • The resulting XML file conforms to the W3C XML version 1.0 and the Namespaces in XML specifications. • To create an XmlTextWriter object a constructor with file straem name or object and encoding type should be used. • Example: • XmlTextWriter xmltw = new XmlTextWriter (“stam.xml", Encoding.Unicode); Rina Zviel-Girshin @Paralex

  50. XmlTextWriter methods • The most important methods are: • WriteStartDocument() - is called to start creating an XML document. This will create the first line in the XML document (a prolog). • WriteStartElement(string) - this method creates a new element in the XML document with the name specified by the string input parameter. (You can also specify a namespace as a second, optional string parameter.) • WriteEndElement() - this method closes off the element created in the WriteStartElement(string) method call. Rina Zviel-Girshin @Paralex

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