protected virtual Expression VisitBinary(FilterDescriptor filter)
{
Expression property =
LinqHelpers.GetPropertyExpression(Parameter, filter.Member);
switch (filter.Operator)
{
case FilterOperator.Contains:
return VisitContains(filter, property);
case FilterOperator.StartsWith:
return VisitStartsWith(filter, property);
case FilterOperator.EndsWith:
return VisitEndsWith(filter, property);
case FilterOperator.IsEqualTo:
return VisitIsEqualTo(filter, property);
case FilterOperator.IsNotEqualTo:
return VisitIsNotEqualTo(filter, property);
case FilterOperator.IsContainedIn:
return VisitIsContainedIn(filter, property);
case FilterOperator.IsGreaterThan:
return VisitIsGreaterThan(filter, property);
case FilterOperator.IsGreaterThanOrEqualTo:
return VisitIsGreaterThanOrEqualTo(filter, property);
case FilterOperator.IsLessThan:
return VisitIsLessThan(filter, property);
case FilterOperator.IsLessThanOrEqualTo:
return VisitIsLessThanOrEqualTo(filter, property);
default:
return Expression.Constant(true);
}
}
public void CanCreateSampleEqualsFilterToIntNullable()
{
var filter = new FilterDescriptor("PropIntNullable", FilterOperator.IsEqualTo, 42);
var expr = new FilterVisitor<ClassA>().MakePredicate(filter);
Assert.AreEqual("x => (x.PropIntNullable = 42)", expr.ToString());
}
public void CanCreateSampleContainsFilterWithNullValue()
{
var filter = new FilterDescriptor("PropString", FilterOperator.Contains, null);
var expr = new FilterVisitor<ClassA>().MakePredicate(filter);
Assert.AreEqual("x => x.PropString.ToUpper().Contains(null)", expr.ToString());
}
public void CanCreateSampleEndsWithFilter()
{
var filter = new FilterDescriptor("PropString", FilterOperator.EndsWith, "asd");
var expr = new FilterVisitor<ClassA>().MakePredicate(filter);
Assert.AreEqual("x => x.PropString.ToUpper().EndsWith(\"ASD\")", expr.ToString());
}
/// <summary>
/// Determines whether the specified <paramref name="other"/> descriptor
/// is equal to the current one.
/// </summary>
/// <param name="other">The other filter descriptor.</param>
/// <returns>
/// True if all members of the current descriptor are
/// equal to the ones of <paramref name="other"/>, otherwise false.
/// </returns>
public virtual bool Equals(FilterDescriptor other)
{
if (ReferenceEquals(null, other))
{
return(false);
}
if (ReferenceEquals(this, other))
{
return(true);
}
return
(Equals(other.Operator, this.Operator) &&
Equals(other.Member, this.Member) &&
Equals(other.Value, this.Value));
}
protected virtual Expression VisitStartsWith(FilterDescriptor filter, Expression property)
{
return VisitStringMethod(filter, property, "StartsWith");
}
protected virtual Expression VisitIsNotEqualTo(FilterDescriptor filter, Expression property)
{
Expression expr = property;
object value = filter.Value;
CheckStringParameters(property, ref expr, ref value);
return Expression.NotEqual(expr, VisitConstantValue(value, property));
}
protected virtual Expression VisitIsLessThanOrEqualTo(FilterDescriptor filter, Expression property)
{
return Expression.LessThanOrEqual(property, VisitConstantValue(filter.Value, property));
}
protected virtual Expression VisitIsGreaterThan(FilterDescriptor filter, Expression property)
{
return Expression.GreaterThan(property, VisitConstantValue(filter.Value, property));
}
protected virtual Expression VisitIsContainedIn(FilterDescriptor filter, Expression property)
{
return VisitEnumerableMethod(filter, property, LinqHelpers.Contains.GetFor(property.Type));
}
public void CanCreateSampleGreaterFilterToClassBWithDoubleValue()
{
var filter = new FilterDescriptor("PropB.PropDecimalNullable", FilterOperator.IsGreaterThan, 42.0);
var expr = new FilterVisitor<ClassA>().MakePredicate(filter);
Assert.AreEqual("x => (x.PropB.PropDecimalNullable > 42)", expr.ToString());
}
public void CanCreateSampleNotEqualsToFilter()
{
var filter = new FilterDescriptor("PropString", FilterOperator.IsNotEqualTo, "asd");
var expr = new FilterVisitor<ClassA>().MakePredicate(filter);
Assert.AreEqual("x => (x.PropString.ToUpper() != \"ASD\")", expr.ToString());
}
public void CanCreateSampleLessFilterToClassBDateTimeNullable()
{
var now = DateTime.Now;
var filter = new FilterDescriptor("PropB.PropDateTimeNullable", FilterOperator.IsLessThan, now);
var expr = new FilterVisitor<ClassA>().MakePredicate(filter);
Assert.AreEqual(string.Format("x => (x.PropB.PropDateTimeNullable < {0})", now.ToString()), expr.ToString());
}
public void CanCreateSampleIsContainedInFilterWithIntList()
{
var list = new[] { 1, 2, 3 };
var filter = new FilterDescriptor("PropInt", FilterOperator.IsContainedIn, list);
Expression<Func<int, bool>> ex = x => list.Contains(x);
var expr = new FilterVisitor<ClassA>().MakePredicate(filter);
Assert.AreEqual("x => value(System.Int32[]).Contains(x.PropInt)", expr.ToString());
}
protected virtual Expression VisitStringMethod(FilterDescriptor filter, Expression property, string methodName)
{
var value = NormalizeStringParameter(filter.Value);
var expr = NormalizeStringExpression(property);
var method = typeof(string).GetMethod(methodName, new Type[] { typeof(string) });
var parameters = new[] {
Expression.Constant(value, typeof(string))
};
return Expression.Call(expr, method, parameters);
}
protected virtual Expression VisitContains(FilterDescriptor filter, Expression property)
{
return VisitStringMethod(filter, property, "Contains");
}
private Expression VisitIsGreaterThanOrEqualTo(FilterDescriptor filter, Expression property)
{
return Expression.GreaterThanOrEqual(property, VisitConstantValue(filter.Value, property));
}
protected virtual Expression VisitEnumerableMethod(FilterDescriptor filter, Expression property, MethodInfo method)
{
var expr = Expression.Constant(filter.Value, typeof(IEnumerable<>).MakeGenericType(property.Type));
var parameters = new[] { expr, property };
return Expression.Call(null, method, parameters);
}
/// <summary>
/// Determines whether the specified <paramref name="other"/> descriptor
/// is equal to the current one.
/// </summary>
/// <param name="other">The other filter descriptor.</param>
/// <returns>
/// True if all members of the current descriptor are
/// equal to the ones of <paramref name="other"/>, otherwise false.
/// </returns>
public virtual bool Equals(FilterDescriptor other)
{
if (ReferenceEquals(null, other))
{
return false;
}
if (ReferenceEquals(this, other))
{
return true;
}
return
Equals(other.Operator, this.Operator) &&
Equals(other.Member, this.Member) &&
Equals(other.Value, this.Value);
}
public void CanCreateSampleEqualsFilterToIntWithQueryableVersion()
{
var filter = new FilterDescriptor("PropInt", FilterOperator.IsEqualTo, 42);
var param = Expression.Parameter(typeof(IQueryable<ClassA>), "q");
var expr = new FilterVisitor<ClassA>().Visit(param, filter);
Assert.AreEqual("q.Where(x => (x.PropInt = 42))", expr.ToString());
}
