I am getting a NULL Reference Exception when trying to pass a NULL list of items as a parameter using Dapper. Normally in my where clause I would simply do the following:

```
"AND (@Sections IS NULL OR Section IN @Sections)";

```

But I am unable to do this because it won't work even when there are items in the sections list. Dapper adds them as parameters and (@sections1,@sections2 IS NULL OR) will error out. If I leave my sections list null because I don't want to use it as a filter I get a NULL reference exception.

My function must have a list of sections as an optional parameter. This way in my code I do not always have to add sections filter to my query. How can I make sections a nullable list in my function params but also work with Dapper when NULL?

**Here is my code:**

```
public static IEnumerable<Product> GetProformaFormularies(int? categoryId = null, IEnumerable<int> sections = null)
{
    using (var context = new AppContext())
    {
        var sql =
        "SELECT * " +
        "FROM Products " +
        "WHERE (@CategoryId IS NULL OR CategoryId = @CategoryId) " +
          "AND (Section IN @Sections)";

        return context.Database.Connection.Query<Product>(sql, 
        new { 
                CategoryId = categoryId,
                Sections = sections
            }).ToList();
    }
}

```

The only solution that I came up with is using Dynamic Parameters. Is there a better way than this?

```
var sql =
    "SELECT * " +
    "FROM ProformaFormulary " +
    "WHERE (@CategoryId IS NULL OR CategoryId = @CategoryId) " +

if (sections != null)
{
    sql += " AND (Section IN @Sections)";
}

var parameters = new DynamicParameters();
parameters.Add("@CategoryId", categoryId);
if (sections != null)
{
    parameters.Add("@Sections", sections);
}

```