Searching over multiple types

Introduction

There are two ways to search over multiple types.

• Implicit-the IClient.Search<T>() method supports inheritance by default. So, no extra effort is required to search over multiple types that share a common base class.
• Use the IncludeType method to create a search request for one type, then include additional types in the request. When doing so, you must provide a projection from the additional type to the return type of the search request, either the original type or some projection. In other words, you can create a search request for BlogPosts and include the Article type in the request, as shown in the following example.

result = client.Search<BlogPost>.For("Banana")
    .IncludeType<BlogPost, Article>(x => 
        new BlogPost 
        { Title = x.Title, Content = x.MainBody })
    .GetResult();

In this case, you search for BlogPosts and Articles and retrieve the results as BlogPosts. However, in most situations, it is preferable to project both types to a third type that is more suitable for search results, like this.

result = searchQuery.For("Banana")
    .Select(x => new SearchResult 
        { Title = x.Title, Content = x.Content })
    .IncludeType<SearchResult, Article>(x => 
        new SearchResult 
        { Title = x.Title, Content = x.MainBody })
    .GetResult();

Limitations

Although you can use the IncludeType method to include additional types, the search request is built towards the first type. So, if you limit the request to search in specific fields and none of those exists in the other types, you only get hits from the first type. In practice, however, if you search through all content without limiting the request to specific fields, or if the types share the same name for fields, this is not a problem.