private Expression <Func <T, bool> > GetFilterExpression(PropertyInfo pi, ColumnFilterValue value)
{
//detect nullable
bool isNullable = pi.PropertyType.IsGenericType &&
pi.PropertyType.GetGenericTypeDefinition() == typeof(Nullable <>);
//get target type:
Type targetType = isNullable ? Nullable.GetUnderlyingType(pi.PropertyType) : pi.PropertyType;
IFilterType filterType = _typeResolver.GetFilterType(targetType);
//build expression to filter collection:
ParameterExpression entityParam = _expression.Parameters[0];
//support nullable types:
Expression firstExpr = isNullable
? Expression.Property(_expression.Body, pi.PropertyType.GetProperty("Value"))
: _expression.Body;
Expression binaryExpression;
if (value.FilterValue.Contains("|"))
{
var filterValues = value.FilterValue.Split('|');
binaryExpression = filterType.GetFilterExpression(firstExpr, filterValues[0], value.FilterType);
for (int i = 1; i < filterValues.Count(); i++)
{
Expression tempExpr = filterType.GetFilterExpression(firstExpr, filterValues[i], value.FilterType);
binaryExpression = Expression.Or(tempExpr, binaryExpression);
}
}
else
{
binaryExpression = filterType.GetFilterExpression(firstExpr, value.FilterValue, value.FilterType);
}
if (binaryExpression == null)
{
return(null);
}
if (targetType == typeof(string))
{
//check for strings, they may be NULL
//It's ok for ORM, but throw exception in linq to objects. Additional check string on null
Expression nullExpr = Expression.NotEqual(_expression.Body, Expression.Constant(null));
binaryExpression = Expression.AndAlso(nullExpr, binaryExpression);
}
else if (isNullable)
{
//add additional filter condition for check items on NULL with invoring "HasValue" method.
//for example: result of this expression will like - c=> c.HasValue && c.Value = 3
MemberExpression hasValueExpr = Expression.Property(_expression.Body,
pi.PropertyType.GetProperty("HasValue"));
binaryExpression = Expression.AndAlso(hasValueExpr, binaryExpression);
}
//return filter expression
return(Expression.Lambda <Func <T, bool> >(binaryExpression, entityParam));
}
public override bool Equals(object obj)
{
if (!(obj is ColumnFilterValue))
{
return(false);
}
ColumnFilterValue compareObject = (ColumnFilterValue)obj;
return(compareObject.ColumnName == ColumnName &&
compareObject.FilterType == FilterType &&
compareObject.FilterValue == FilterValue);
}
public IQueryable <T> ApplyFilter(IQueryable <T> items, ColumnFilterValue value)
{
if (value == ColumnFilterValue.Null)
{
throw new ArgumentNullException("value");
}
var pi = (PropertyInfo)((MemberExpression)_expression.Body).Member;
Expression <Func <T, bool> > expr = GetFilterExpression(pi, value);
if (expr == null)
{
return(items);
}
return(items.Where(expr));
}
public QueryStringFilterSettings(HttpContext context)
{
if (context == null)
{
throw new ArgumentException("No http context here!");
}
Context = context;
string[] filters = Context.Request.QueryString.GetValues(DefaultTypeQueryParameter);
if (filters != null)
{
foreach (string filter in filters)
{
ColumnFilterValue column = CreateColumnData(filter);
if (column != ColumnFilterValue.Null)
{
_filterValues.Add(column);
}
}
}
}
public QueryStringFilterSettings(IQueryDictionary <StringValues> query)
{
if (query == null)
{
throw new ArgumentException("No http context here!");
}
Query = query;
var filters = Query.Get(DefaultTypeQueryParameter);
if (filters.Count > 0)
{
foreach (string filter in filters)
{
ColumnFilterValue column = CreateColumnData(filter);
if (column != ColumnFilterValue.Null)
{
_filterValues.Add(column);
}
}
}
}
public QueryStringFilterSettings(IQueryCollection query)
{
if (query == null)
{
throw new ArgumentException("No http context here!");
}
Query = query;
string[] filters = Query[DefaultTypeQueryParameter].Count > 0 ?
Query[DefaultTypeQueryParameter].ToArray() : null;
if (filters != null)
{
foreach (string filter in filters)
{
ColumnFilterValue column = CreateColumnData(filter);
if (column != ColumnFilterValue.Null)
{
_filterValues.Add(column);
}
}
}
}