public static IQueryable ApplyEqualityFilter(IQueryable source, string propertyName, object value)
{
ParameterExpression parameterExpression = Expression.Parameter(source.ElementType, String.Empty);
Expression propertyExpression = CreatePropertyExpression(parameterExpression, propertyName);
if (Nullable.GetUnderlyingType(propertyExpression.Type) != null && value != null)
{
propertyExpression = Expression.Convert(propertyExpression, Misc.RemoveNullableFromType(propertyExpression.Type));
}
value = Misc.ChangeType(value, propertyExpression.Type);
Expression compareExpression = Expression.Equal(propertyExpression, Expression.Constant(value));
LambdaExpression lambda = Expression.Lambda(compareExpression, parameterExpression);
MethodCallExpression whereCall = Expression.Call(typeof(Queryable), "Where", new Type[] { source.ElementType }, source.Expression, Expression.Quote(lambda));
return(source.Provider.CreateQuery(whereCall));
}
/// <summary>
/// Look for this table's primary key in the route values (i.e. typically the query string).
/// If they're all found, return a DataKey containing the primary key values. Otherwise return null.
/// </summary>
public DataKey GetDataKeyFromRoute()
{
var queryStringKeys = new OrderedDictionary(PrimaryKeyNames.Length);
foreach (MetaColumn key in PrimaryKeyColumns)
{
// Try to find the PK in the route values. If any PK is not found, return null
string value = Misc.GetRouteValue(key.Name);
if (string.IsNullOrEmpty(value))
{
return(null);
}
queryStringKeys[key.Name] = Misc.ChangeType(value, key.ColumnType);
}
return(new DataKey(queryStringKeys, PrimaryKeyNames));
}
