HTTP Services With WCF 4 and Windsor

Although a bit old, I found the following article, Vanilla Yet Composable HTTP Services With WCF 4 and Windsor, extremely helpful.

The article shows how to easily create services, and have their dependencies automatically resolved by the Windsor container, with minimal changes.

SharePoint Client Object Model: Adding a Site Column only if it does not already exist

Before creating a new Site Column, you should make sure that the column doesn't already exist. At the very least, make sure that the ID you are using isn't already taken. The sample below uses the FindField method from a previous post:

public static Field EnsureField(this ClientContext clientContext, Web web, Guid id, string name, string schema)
{
	var field = FindField(clientContext, web, f => f.Id == id);
	if (field != null)
		return field;

	var newField = web.Fields.AddFieldAsXml(schema, false,
		AddFieldOptions.AddToNoContentType | AddFieldOptions.AddFieldInternalNameHint);
	clientContext.ExecuteQuery();
	return newField;
}

SharePoint Client Object Model: Verifying if a Field is part of a Content Type

Before adding a field to a ContentType, it is important to check that the field is not already part of the Content Type. Here's an extension method to ClientContext that does just that:

public static bool ExistInContentType( this ClientContext clientContext, ContentType contentType, Field field)
{
	var fieldLinks = contentType.FieldLinks;
	var existingFields = clientContext.LoadQuery(fieldLinks.Where(fl => fl.Id == field.Id));
	clientContext.ExecuteQuery();
	var existingField = existingFields.FirstOrDefault();
	if (existingField != null)
		return true;
	return false;
}

SharePoint Client Object Model: Finding a field in a list

When working with the SharePoint Client Object Model, it is useful to find a field in a list, or a site column in the web. Below are some extension methods to ClientContext, to facilitate these:

public static class FieldClientContextExtensions
{
    public static Field FindField(this ClientContext clientContext, List list,                                       
        Expression<Func<Field, bool>> predicate)
    {
        var webFields = list.Fields;
        var matchingFields = clientContext.LoadQuery(webFields.Where(predicate));
        clientContext.ExecuteQuery();

        Field field = matchingFields.FirstOrDefault();
        return field;
    }

    public static Field FindField(this ClientContext clientContext, Web web, Expression<Func<Field, bool>> predicate)
    {
        var webFields = web.Fields;
        var allFields = web.AvailableFields;
        var matchingWebFields = clientContext.LoadQuery(webFields.Where(predicate));
        var matchingAllFields = clientContext.LoadQuery(allFields.Where(predicate));

        clientContext.ExecuteQuery();
        Field field = matchingWebFields.FirstOrDefault() ?? matchingAllFields.FirstOrDefault();
        return field;
    }
}

Windsor: Loading installers from the execution folder

When using Windsor, it is necessary to load the various IWindowsInstallers into the container. One standard way of doing this is using a code similar to the below:

container.Install(FromAssembly.InDirectory(new AssemblyFilter(".")));

The above code will load all the installed that are located in the execution folder.

However, in certain cases, when your code is running in different contexts, such as under IIS, you need to be a bit more explicit about things. You need to tell Windsor to load assemblies from the folder where you are running, and not from some run-time "copy" or cache folder.

For that, you can use the following class:

public class ExecutingAssemblyFilter : AssemblyFilter
{
    public ExecutingAssemblyFilter()
        : base(new FileInfo(new Uri(Assembly.GetExecutingAssembly).CodeBase).LocalPath).Directory.ToString())
    { }
 }

This class inherits from AssemblyFilter, and automatically provides the correct path. It should be used like this:

container.Install(FromAssembly.InDirectory(new ExecutingAssemblyFilter()));