Develop Reference

Roslyn Check If Field Declaration has been assigned to

I'm writing an app which converts keys to use resources from a RESX File. This code was working with local variables before:
public static void AnalyzeConstDeclaration(SyntaxNodeAnalysisContext context)
{
var fieldDeclaration = (FieldDeclarationSyntax)context.Node;
if (false == IsValidFieldDeclaration(context, fieldDeclaration))
{
return;
}
var firstVariable = fieldDeclaration.Declaration.Variables.FirstOrDefault();
var dataFlowAnalysis = context.SemanticModel.AnalyzeDataFlow(firstVariable);
var variableSymbol = context.SemanticModel.GetDeclaredSymbol(firstVariable);
if (dataFlowAnalysis.WrittenOutside.Contains(variableSymbol))
{
return;
}
var firstSymbol = context.SemanticModel.GetDeclaredSymbol(firstVariable);
context.ReportDiagnostic(Diagnostic.Create(Rule, context.Node.GetLocation(), firstSymbol.Name));
}
However when I try to get the dataFlowAnalysis I receive an error:
Additional information: statementOrExpression is not a StatementSyntax or an ExpressionSyntax.
How can Ideally just need to see if anyone has written to this variable outside of the declaration.

DataFlow works by analyzing order of execution within a single method.
It doesn't make sense for class-level fields.
Instead, you should use a simple syntax visitor (or SymbolFinder) to search the entire class for assignments to the field.
You'll probably also want to check whether it's ever passed as a ref parameter.

How to get the value of a property of a class in a non executing assembly through reflection

I'm having trouble while getting the value of the text property in a non-executing assembly; I read an assembly from disk via reflection, then i get all classes in the assembly to search for the Text property in a windows form class which is initialized by win forms designer. So far i have the following code:
static void Main(string[] args)
{
Assembly asm = Assembly.LoadFrom(Path.Combine(path, "Assembly.exe"));
PropertyInfo[] props;
foreach (Type t in asm.GetTypes())
{
var value = t.GetProperty("Text").GetValue(/*Not sure what to put here*/)
}
}
And this is how the designer generated the form
Me.AutoScaleMode = System.Windows.Forms.AutoScaleMode.None
Me.BackColor = System.Drawing.Color.FromArgb(CType(CType(0, Byte), Integer), CType(CType(128, Byte), Integer), CType(CType(128, Byte), Integer))
Me.ClientSize = New System.Drawing.Size(234, 181)
Me.Cursor = System.Windows.Forms.Cursors.Default
Me.Font = New System.Drawing.Font("Arial", 8.25!, System.Drawing.FontStyle.Bold, System.Drawing.GraphicsUnit.Point, CType(0, Byte))
Me.ForeColor = System.Drawing.SystemColors.WindowText
Me.FormBorderStyle = System.Windows.Forms.FormBorderStyle.FixedDialog
Me.Location = New System.Drawing.Point(581, 222)
Me.MaximizeBox = False
Me.MinimizeBox = False
Me.Name = "winform"
Me.RightToLeft = System.Windows.Forms.RightToLeft.No
Me.StartPosition = System.Windows.Forms.FormStartPosition.Manual
Me.Text = "Title"
Me.fraDías.ResumeLayout(False)
Me.ResumeLayout(False)
Keep in mind that the assembly is on disk and non-executing and that I want to retrieve the value of the Text property of every winform (I guess it should be somewhere hardcoded in the assembly since it was generated by the winforms designer)
Please tell me if this is possible, thanks!

Your requirements are contradictory, when you load an aseembly via reflection, and instantiate an object or try to get a property value, what happens is that some code begins to run, there is no way around that.
Remember that properties are just "syntax sugar" for a pair of methods, the getter and setter. Their current value is nothing but the value returned by the getter method, and when you change its value, you're in fact calling its setter method. So, to retrieve property values, you must make some code to run, even if it's a trivial get method.
I think maybe your confusion comes from the fact that you're using a designer to create the form. Particularly with the WinForms designer (WPF for instance is substantially different), all it does is to autogenerate some code for you. Setting properties, placing and moving controls around, what's happening under the hood is that it writes code that replicate your actions at runtime, specifically, it codes the InitializeComponent method. The real property value is set when the constructor is called (that in turn calls InitializeComponent), and then you may read/change using many properties.
What you would need to read those designer attributes is that those were hardcoded in some form of metadata, so that it's simply read as data and not as the result of code execution. That's not the case with WinForms, as it "saves" the form as code.

You cannot read a property of a class that has not been instantiated! The parameter you are missing is an instance of your type.
You must create an instance of the type with object o = Activator.CreateInstance(type); before accessing its members (unless they are static).
Your problem is related to how add-ins (plug-ins) can be loaded at runtime.
Here is how I made an Add-In Loader. Below, I will explain how you can adapt it to your problem. Add-Ins have to implement the IAddIn interface in my example. You are totally free in the definition of IAddIn. You could define it like this:
public interface IAddIn
{
bool OnLoad();
string Version { get; set; }
string Text { get; set; }
}
This allows you to access members without reflection.
public class AddInLoader
{
// Loads all non abstract types implementing IAddIn in all DLLs found in a folder.
public IList<IAddIn> Load(string folder)
{
var addIns = new List<IAddIn>();
string[] files = Directory.GetFiles(folder, "*.dll");
foreach (string file in files) {
addIns.AddRange(LoadFromAssembly(file));
}
return addIns;
}
// Loads all non abstract types implementing IAddIn found in a file.
private static IEnumerable<IAddIn> LoadFromAssembly(string fileName)
{
Assembly asm = Assembly.LoadFrom(fileName);
string addInInterfaceName = typeof(IAddIn).FullName;
foreach (Type type in asm.GetExportedTypes()) {
Type interfaceType = type.GetInterface(addInInterfaceName);
if (interfaceType != null &&
(type.Attributes & TypeAttributes.Abstract) != TypeAttributes.Abstract){
IAddIn addIn = (IAddIn)Activator.CreateInstance(type);
addIn.Version = asm.GetName().Version.ToString();
yield return addIn;
}
}
}
}
Now you can load and access the add-ins like this:
var loader = new AddInLoader();
IList<IAddIn> addIns = loader.Load(folderPath);
foreach (IAddIn addIn in addIns) {
if (addIn.OnLoad()) {
Console.WriteLine("Version = {0}, Text = {1}", addIn.Version, addIn.Text);
}
}
Reading the titles of Forms at runtime:
You can easily adapt this example. Instead of searching for types implementing an interface, search for types deriving from System.Windows.Forms.Form.
private static IEnumerable<Form> LoadFormsFromAssembly(string fileName)
{
Assembly asm = Assembly.LoadFrom(fileName);
foreach (Type type in asm.GetExportedTypes()) {
if (typeof(Form).IsAssignableFrom(type) &&
(type.Attributes & TypeAttributes.Abstract) != TypeAttributes.Abstract) {
Form form = (Form)Activator.CreateInstance(type);
yield return form;
}
}
}
Now you can get the texts of the forms like this:
var forms = LoadFormsFromAssembly(path);
foreach (Form frm in forms) {
Console.WriteLine(frm.Text);
}
Note: You must instantiate the forms, however you do not need to open (show) them. The code works only if the forms have a default constructor, i.e. a constructor without parameters.

You need an instance object for that type to get the value of a property.
It looks like you just want to check if a type has a "Text" property or not. You can to it by checking
bool hasTextProperty = t.GetProperty("Text") !=null;

Why do I have to manually create ExpandoObject to properly use the dynamic keyword?

I was looking at the question Use 'dynamic' throw a RuntimeBinderException. I face a similar problem:
Basically, I want to create a "HTML helper" in ASP.NET MVC that uses dynamic arguments, akin to the htmlArguments parameter for many of the existing helpers (more code below):
public BootstrapCell(Action<string> emitContentAction, dynamic args)
View:
#using (grid.Cell(ViewContext.Writer.Write, new {Position = 4}))
{
<p>zomg!</p>
}
However in the naive approach, i get RuntimeBinderException thrown at me, declaring that 'object' does not contain a definition for 'Position', even though when debugging and hovering over the _args variable, it clearly does have a Position property.
The caller and the callee are in separate assemblies. Why is that problem happening?
(The solution to that has been shown in the same question: Manually create an ExpandoObject to hold the args.)
Implementation:
public class Cell
{
private readonly string _tagName;
private dynamic _args;
private Action<string> EmitContentAction;
public BootstrapCell(Action<string> emitContentAction, dynamic args) : DisposableBaseClass
{
_args = args;
EmitContentAction = emitContentAction;
OnContextEnter();
}
protected void OnContextEnter()
{
var sb = new StringBuilder("<");
sb.Append(_tagName);
if (_args.Position > 0)
{
sb.Append(" class=\"offset");
sb.Append(args.Position);
sb.Append("\"");
}
sb.Append(">");
EmitContentAction(sb.ToString());
}
}
[Edited to make clearer that my problem arises when "obviously" the Position property is set. I am aware that if the property never was defined in the first place, an exception must be raised.]

That code is fatally flawed.
It does work, as long as you specify that property:
void Bar()
{
Foo(new {Position = 0});
}
void Foo(dynamic args)
{
Console.WriteLine(args.Position);
}
That will output 0, it will not throw a RuntimeBinderException.
But the purpose of such code is the possibility for the caller to specify only the properties needed and omit the rest.
You are trying to check for this omission via if(args.Position != null). But that doesn't work, it already requires Position to exist.
When you have a look at the routing API of ASP.NET that also supports those anonymous configuration objects you will notice that the type of the parameter is object and not dynamic.
Using object instead of dynamic will enable your API to be used across assembly boundaries.
So how does it work?
Just like in the linked answer, you need to manually create a dictionary of the properties. Whether you use a plain old Dictionary<string, object> or an ExpandoObject is a matter of preference.
Using ExpandoObject will make your code a bit simpler to read and write, but it is not required.
About the actual exception you are getting:
Please note that it tells you it can't find the Position property on object. If it would be an anonymous type that was missing the Position property the exception message wouldn't refer to object but to an anonymous type. Something like this:
'<>f__AnonymousType0' does not contain a definition for 'Position'

sitecore RSS caching

I have been working on implementing a custom RSS feed in sitecore 6.4. My custom behaviour is very limited, all i effectively wanted to is add a link for author (our author field is a reference field so we cannot use the built in author attribution).
I overrode RenderItem() on the PublicFeed class so that i could make use of my own implementation of the FeedRenderer class (where the author logic is housed). my approach follows this pattern outlined by John West for adding your own rendering behaviour:
public class MyPUblicFeed: PublicFeed
{
protected override SyndicationItem RenderItem(Item item)
{
Assert.ArgumentNotNull(item, "item");
Control rendererControl = FeedUtil.GetFeedRendering(item);
if (rendererControl == null)
{
return null;
}
using (new ContextItemSwitcher(item))
{
var myRenderer= rendererControl as MyFeedRenderer;
if (myRenderer!= null)
{
myRenderer.Database = SitecoreHelper.CurrentDatabase.Name;
return myRenderer.RenderItem();
}
var renderer = rendererControl as Sitecore.Web.UI.WebControls.FeedRenderer;
if (renderer != null)
{
renderer.Database = SitecoreHelper.CurrentDatabase.Name;
return renderer.RenderItem();
}
}
throw new InvalidOperationException("FeedRenderer rendering must be of Sitecore.Web.UI.WebControls.FeedRenderer type");
}
}
And now for my rendering class:
public class MyFeedRenderer: Sitecore.Web.UI.WebControls.FeedRenderer
{
public override SyndicationItem RenderItem()
{
Item item = base.GetItem();
var syndicationItem = base.RenderItem();
//unfortunately we have to parse params again :(
FeedRenderingParameters feedRenderingParameter = FeedRenderingParameters.Parse(base.Parameters);
AddAuthor(syndicationItem, item, feedRenderingParameter);
return syndicationItem;
}
private static void AddAuthor(SyndicationItem syndicationItem, Item item, FeedRenderingParameters feedRenderingParameter)
{
//clear out authors added by base class
syndicationItem.Authors.Clear();
//logic for adding author here
}
}
this all works great, outputting exactly what i want, but the caching element doesn't appear to be working. I have set the cacheable flag on the actual item itself with a timespan of 01:00:00. This didn't appear to work - if i put a breakpoint in either of the above classes it is hit everytime the feed is requested.
so then i tried to enable caching at a control level, turning caching on with VaryByData for the MyFeedRenderer rendering. alas this isn't working either, the breakpoint is hit every time.
Can anyone offer any advice on this matter? the documentation simply recommends turning it on on the actual feed item, not at the Rendering level, but neither seem to be working for me. Interestingly HTML caching is working elsewhere - is RSS also put into the HTML cache?
Thanks in advance,
Nick

-Ensure the Cacheable checkbox in the feed definition item is checked.
-Ensure that you have published the feed definition item.
-If you do not populate the Cache Duration field in the feed definition item, it should default to one day.
-Feeds appear to cache in Sitecore.Syndication.FeedManager.Cache rather than the site output cache. Inspect that cache object in the Visual Studio debugger after calling your feed, and then again after calling that feed a second time, to try to see if any records appear, and if multiple cache keys appear for the same feed. Investigate the Render() method; if PublicFeed.IsCacheable() returns false (depending on the Cacheable field in the feed definition item), PublicFeed.Render() does not cache.
-Ensure nothing else clears caches between your requests for the feed.
SDN forum thread: http://sdn.sitecore.net/forum/ShowPost.aspx?PostID=40591

C# - Increment through a list of webservices in a directory and list available Webmethods

I have a number of different webservices in the C# web application I'm building and would like to create a quick documentation page which lists all of the webservices and the available web methods in each. Rather than having to keep the documentation page up-to-date whenever I change/add a webmethod it would be good if the documentation was dynamic.
For each webmethod I'd like to get the Description attribute from the Webmethod deceleration and (if possible) the list of parameters for each method.
I know I can get a lot of this info from the web service summary page that .NET serves for a .asmx page but I don't want to force the user to have to keep clicking away from the main documentation page.
Thanks in advance.

A quick solution would be to write a custom Http Handler:
public class InformationHandler : IHttpHandler
{
public void ProcessRequest(HttpContext context)
{
// Select the assembly that contains the web service classes
var assemblyThatContainsTheWebService = Assembly.GetExecutingAssembly();
// Select all types in this assembly deriving from WebService
var webServiceTypes =
from type in assemblyThatContainsTheWebService.GetTypes()
where type.BaseType == typeof(WebService)
select type;
context.Response.ContentType = "text/plain";
foreach (var type in webServiceTypes)
{
context.Response.Write(string.Format("Methods for web service {0}:{1}", type, Environment.NewLine));
// Select all methods marked with the WebMethodAttribute
var methods =
from method in type.GetMethods()
where method.GetCustomAttributes(typeof(WebMethodAttribute), false).Count() > 0
select method;
foreach (var method in methods)
{
context.Response.Write(method);
}
context.Response.Write(Environment.NewLine);
}
}
public bool IsReusable
{
get
{
return false;
}
}
}