private Expression GetExpression(Expression binaryExpression, ColumnFilterValue value, Type targetType,
MethodInfo removeDiacritics)
{
IFilterType filterType = _typeResolver.GetFilterType(targetType);
//support nullable types:
Expression firstExpr = IsNullable
? Expression.Property(_expression.Body, _pi.PropertyType.GetProperty("Value"))
: _expression.Body;
var filterExpression = filterType.GetFilterExpression(firstExpr, value.FilterValue, value.FilterType, removeDiacritics);
if (filterExpression == null)
{
return(null);
}
if (IsNullable && targetType != typeof(string))
{
//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"));
filterExpression = Expression.AndAlso(hasValueExpr, filterExpression);
}
binaryExpression = binaryExpression == null ? filterExpression :
Expression.AndAlso(binaryExpression, filterExpression);
//return filter expression
return(binaryExpression);
}
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));
}
private string GetFilterString(ColumnFilterValue value)
{
string result = "";
// get column name
List <string> names = new List <string>();
Expression expression = _expression.Body;
while (expression.NodeType != ExpressionType.Parameter)
{
names.Add(((MemberExpression)expression).Member.Name);
expression = ((MemberExpression)expression).Expression;
}
for (int i = names.Count - 1; i >= 0; i--)
{
result += names[i];
if (i != 0)
{
result += "/";
}
}
if (!string.IsNullOrWhiteSpace(result))
{
if (value.FilterType == GridFilterType.IsNull)
{
result += " eq null";
}
else if (value.FilterType == GridFilterType.IsNotNull)
{
result += " ne null";
}
else
{
//get target type:
Type targetType = IsNullable ? Nullable.GetUnderlyingType(_pi.PropertyType) : _pi.PropertyType;
IFilterType filterType = _typeResolver.GetFilterType(targetType);
result = filterType.GetFilterExpression(result, value.FilterValue, value.FilterType);
}
}
return(result);
}
private Expression <Func <T, bool> > GetFilterExpression(PropertyInfo pi, ColumnFilterValue value)
{
//detect nullable
bool isNullable = pi.PropertyType.GetTypeInfo().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 = 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));
}
private Expression GetExpression(PropertyInfo pi, ColumnFilterValue value)
{
//detect nullable
bool isNullable = pi.PropertyType.GetTypeInfo().IsGenericType&&
pi.PropertyType.GetGenericTypeDefinition() == typeof(Nullable <>);
//get target type:
Type targetType = isNullable ? Nullable.GetUnderlyingType(pi.PropertyType) : pi.PropertyType;
List <string> names = new List <string>();
Expression expression = _expression.Body;
while (expression.NodeType != ExpressionType.Parameter)
{
names.Add(((MemberExpression)expression).Member.Name);
expression = ((MemberExpression)expression).Expression;
}
Expression binaryExpression = null;
for (int i = names.Count - 1; i >= 0; i--)
{
expression = Expression.Property(expression, names[i]);
var nestedPi = (PropertyInfo)((MemberExpression)expression).Member;
//detect nullable
bool nestedIsNullable = nestedPi.PropertyType.GetTypeInfo().IsGenericType&&
nestedPi.PropertyType.GetGenericTypeDefinition() == typeof(Nullable <>);
//get target type:
Type nestedTargetType = nestedIsNullable ? Nullable.GetUnderlyingType(nestedPi.PropertyType) : nestedPi.PropertyType;
// Check for null on nested properties and target object if it's a string
// It's ok for ORM, but throw exception in linq to objects
if (nestedIsNullable || nestedTargetType == typeof(string))
{
binaryExpression = binaryExpression == null?
Expression.NotEqual(expression, Expression.Constant(null)) :
Expression.AndAlso(binaryExpression, Expression.NotEqual(expression, Expression.Constant(null)));
}
}
IFilterType filterType = _typeResolver.GetFilterType(targetType);
//support nullable types:
Expression firstExpr = isNullable
? Expression.Property(_expression.Body, pi.PropertyType.GetProperty("Value"))
: _expression.Body;
var filterExpression = filterType.GetFilterExpression(firstExpr, value.FilterValue, value.FilterType);
if (filterExpression == null)
{
return(null);
}
if (isNullable && targetType != typeof(string))
{
//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"));
filterExpression = Expression.AndAlso(hasValueExpr, filterExpression);
}
binaryExpression = binaryExpression == null ? filterExpression :
Expression.AndAlso(binaryExpression, filterExpression);
//return filter expression
return(binaryExpression);
}
private Expression GetExpression(ColumnFilterValue value, MethodInfo removeDiacritics)
{
//get target type:
Type targetType = IsNullable ? Nullable.GetUnderlyingType(_pi.PropertyType) : _pi.PropertyType;
List <string> names = new List <string>();
Expression expression = _expression.Body;
while (expression.NodeType != ExpressionType.Parameter)
{
names.Add(((MemberExpression)expression).Member.Name);
expression = ((MemberExpression)expression).Expression;
}
Expression binaryExpression = null;
for (int i = names.Count - 1; i >= 0; i--)
{
expression = Expression.Property(expression, names[i]);
var nestedPi = (PropertyInfo)((MemberExpression)expression).Member;
//detect nullable
bool nestedIsNullable = nestedPi.PropertyType.GetTypeInfo().IsGenericType&&
nestedPi.PropertyType.GetGenericTypeDefinition() == typeof(Nullable <>);
//get target type:
Type nestedTargetType = nestedIsNullable ? Nullable.GetUnderlyingType(nestedPi.PropertyType) : nestedPi.PropertyType;
// Check for null on nested properties and not value type (string and objects are reference type)
// It's ok for ORM, but throw exception in linq to objects
if (nestedIsNullable || !nestedTargetType.IsValueType)
{
binaryExpression = binaryExpression == null?
Expression.NotEqual(expression, Expression.Constant(null)) :
Expression.AndAlso(binaryExpression, Expression.NotEqual(expression, Expression.Constant(null)));
}
}
// return expression for IsNull and IsNotNull
if (value.FilterType == GridFilterType.IsNull)
{
value.FilterValue = "";
if (targetType == typeof(string))
{
return(GetExpression(binaryExpression, value, targetType, removeDiacritics));
}
else if (IsNullable)
{
return(binaryExpression == null?
Expression.Equal(_expression.Body, Expression.Constant(null)) :
Expression.OrElse(Expression.Not(binaryExpression), Expression.Equal(expression, Expression.Constant(null))));
}
else
{
return(binaryExpression == null ? null : Expression.Not(binaryExpression));
}
}
else if (value.FilterType == GridFilterType.IsNotNull)
{
value.FilterValue = "";
if (targetType == typeof(string))
{
return(GetExpression(binaryExpression, value, targetType, removeDiacritics));
}
else if (IsNullable)
{
return(binaryExpression == null?
Expression.NotEqual(_expression.Body, Expression.Constant(null)) :
Expression.AndAlso(binaryExpression, Expression.NotEqual(expression, Expression.Constant(null))));
}
else
{
return(binaryExpression);
}
}
else
{
return(GetExpression(binaryExpression, value, targetType, removeDiacritics));
}
}