Neal Stublen [email protected]. How does XMLReader work? XmlReader.Read() Advances to next node...
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Transcript of Neal Stublen [email protected]. How does XMLReader work? XmlReader.Read() Advances to next node...
How does XMLReader work?
XmlReader.Read()Advances to next nodeXmlReader properties access node name,
value, attributes, etc.Returns false if there are no additional
nodes
Reading XML FilesXmlReader r = XmlReader.Create(path, settings);
r.ReadToDescendant(nodeName);
do{ r.ReadStartElement(nodeName); r.ReadElementContentAsString();} while (r.ReadToNextSibling(nodeName));
r.Close();
Code Practice
Create a new project called CustomerImport
Import Customers into a List<> from any .xml file
Fill a TreeView with the Customer data
var Data Type We can declare a variable as type “var”
instead of using a specific data type
The compiler assigns an implicit data type at compile-time (not run-time)
var value = 0;var array = new string[10];var list = new List<Customer>();
var str = "Hello"; // str is string typestr = 6; // can’t assign int
What’s LINQ?
SQL-like query expression on any enumerable object type
int[] numbers = new int[100];for (int index = 0; index < 100; ++index){ numbers[index] = index;}
var odds = from number in numbers where number % 2 != 0 select number;
Try it in LINQPad
Duplicate code from previous slide Filter out prime numbers from array
using LINQ query
LINQ Expressionsfrom [type] element in collection
join element2 in collection2on key1 equals key2
where condition // any boolean expression
orderby expression [ascending|descending]
select columnExpressionselect new [type] { name=value, name=value }
LINQ Expressionsfrom cust in customers
join invoice in invoiceson cust.CustomerID equals invoice.CustomerID
where invoice.InvoiceDate < sixtyDaysAgo
orderby invoice.InvoiceTotal descending
select
Try it with CustomerImport Create a List<Customer> object by
looping through SqlDataReader Perform LINQ queries on
List<Customer>
LINQ-to-SQL
Create objects that represent database entities
Use the same LINQ query expressions against a database
Just restricts “where” clause to SQL-compatible operations
LINQ on Database Objects Add LINQ data objects to a project Drop tables from Server Explorer Use the new DB to query the database
using LINQ Insert, Update, Delete objects,
db.SubmitChanges() Add related items, db.SubmitChanges() Paging: (from…).Skip(5).Take(5)
LINQ’d Customer-Invoice List
Using LINQ objects, fill a list view with all invoices sorted by CustomerName
ToolTips and HelpProviders Add ToolTip control Set ToolTip property on each control and/or
the form Hover over control to show tool tip
Add HelpProvider control Set the HelpString on each property and/or
the form Press F1 while the control has focus to show
help string