There are couple of steps for this.
You will have to:
- Create a
ISearchCriteria
object; - Create an search expression from the criteria object, including the docType alias as a field to be searched;
- Search using the expression.
This can be coded as:
var criteria = ExamineManager.Instance.CreateSearchCriteria();
var expression = criteria.Field("nodeTypeAlias", "yourDocTypeAlias")
.And()
.Field("nodeName", searchTerm);
var results = ExamineManager.Instance.Search(expression.Compile());
This is possible because when Umbraco publishes a node, it saves the node's docType alias to the search index.
There is more Examine documentation here. I would also recommend downloading Luke which is a standalone tool that will allow you to look inside an index so you can see what is actually stored by Umbraco.