CODEWITHSUNDEEP
c#linq
Brian Leeming
Brian Leeming

Reputation: 11730

GetProperties cannot be made generic in Linq statement

I have the following code:

public static IList<SortOption> SortValues()
{
var sortValues = (from prop in typeof(SolrSchemaApp1).GetProperties(BindingFlags.Instance | BindingFlags.Public)
  where Attribute.IsDefined(prop, typeof(SolrSortAttribute)) 
  select new SortOption(prop.Name)).ToList();
return sortValues;
}

where SolrSchemaApp1 is a class derived from an interface called ISolrDocument.

I want to pass in an instance of SolrSchemaApp2 and make my code select the sort properties from that one instead of SolrSchemaApp1. In effect, I want to do this:

public static IList<SortOption> SortValues(ISolrDocument schemaToScan)
{
var sortValues = (from prop in typeof(schemaToScan).GetProperties(BindingFlags.Instance | BindingFlags.Public)
  where Attribute.IsDefined(prop, typeof(SolrSortAttribute))
  select new SortOption(prop.Name)).ToList();
return sortValues;
}

All I have done is replaced the hard coded SolrSchemaApp1 with a variable of a different type. However, I get the error

The type or namespace name 'schemaToScan' could not be found (are you missing a using directive or an assembly reference?)

I'm struggling with the syntax of using GetProperties on an arbitrary class.

How do I use Linq to scan the properties of the class that I pass in as a parameter?

Upvotes: 0

Views: 175

Answers (3)

Marc Gravell
Marc Gravell

Reputation: 1063318

schemaToScan is not a type (it is a parameter), so typeof(schemaToScan) makes no sense. You have 3 options, all of which have slightly different meanings:

1: hard-code to typeof(ISolrDocument) if the property is on the interface

2: use schemaToScan.GetType() if the property is on the concrete type of the implementing object

3: make it a generic method, and use typeof(T) if the property is on the declared type of the variable (not object) being passed:

    public static IList<SortOption> SortValues<T>(T schemaToScan)
        where T : ISolrDocument
    { ... }

Upvotes: 1

David Hoerster
David Hoerster

Reputation: 28701

First off, use schemaToScan.GetType() instead of typeof(schemaToScan) -- typeof is used to get the Type for a type name. Use GetType() for getting the Type of an instance.

Upvotes: 0

Rapha&#235;l Althaus
Rapha&#235;l Althaus

Reputation: 60503

replace typeof(schemaToScan)

by 

schemaToScan.GetType()

schemaToScan is an instance of a type, not a type.

Upvotes: 5

Related Questions