Question

I have the following class in my C# .NET 3.5 win forms app:

class Field {  string objectName; string objectType; string fieldName; string fieldValue;   } 

and a List fieldList that is a datasource for a checkedlistbox. This listbox shows all the distinct objectNames from my fieldList collection.

I want to create another checkedlistbox that contains fieldNames, but only shows fieldnames that have an associated checked objectName in the first list box.

So my question is how can I query the DataSource of the original list of objectNames to return the distinct set of fieldNames that are associated with a selected objectName?

That is not very easy to read so I will give an example:

Field1 {  objectName = 'objA' FieldName = 'FieldA'  }  Field2 {  objectName = 'objA' FieldName = 'FieldB'  }   Field3 {  objectName = 'objB' FieldName = 'FieldA'  }  Field4 {  objectName = 'objC' FieldName = 'FieldC'  } 

So suppose in my checkbox I select objectNames objA and objB. Then my returned fields would be ‘FieldA’ and ‘FieldB’.

How can I achieve this using LINQ or filtering my generic list of Fields? Can I utilise the ‘select’ or ‘where’ methods that are available to a list?

Answer 1

var selectedNames = ... // List of selected names var selectedFields = (from f in fieldList                       where selectedNames.Contains(f.objectName)                       select f.FieldName).Distinct().ToList();