private static void GetSelection(IFilterData data, out ParameterExpression parameterExp, out Expression propertyExp)
{
var childTree = FilterDataHelper.CreateChildTree(data);
var parentData = GetParent(childTree);
parameterExp = Expression.Variable(parentData.PropertyType);
propertyExp = CreatePropertyOrSelect(childTree, parameterExp, data);
}
private static void CreateParameters(IFilterData data, object value, out ParameterExpression parameterExp, out ConstantExpression constExp, out Expression propertyExp)
{
var childTree = FilterDataHelper.CreateChildTree(data);
var parentData = GetParent(childTree);
parameterExp = Expression.Variable(parentData.PropertyType);
constExp = Expression.Constant(value);
propertyExp = CreatePropertyExp(childTree, parameterExp);
}
private static Expression CreateSelect(Expression parentExp, IFilterData propertyInfo, IFilterData data)
{
var newData = data.Copy();
var inner = FilterDataHelper.ChangeInnerParent(propertyInfo.Parent, newData);
var innerLambda = PropertySelector(newData);
var collectionType = parentExp.Type.GetInterface(nameof(IQueryable)) != null? typeof(Queryable) : parentExp.Type.GetInterface(nameof(IEnumerable)) != null ? typeof(Enumerable) : throw new ArgumentException(parentExp.Type.Name);
var select = collectionType.GetMethods(BindingFlags.Static | BindingFlags.Public).First(m => m.Name == "Select" && m.GetParameters().Length == 2).MakeGenericMethod(new[] { inner.PropertyType, innerLambda.ReturnType });
return(Expression.Call(select, parentExp, innerLambda));
}
internal static LambdaExpression LikeStringPredicate(IFilterData data, string value)
{
CreateParameters(data, value, out var parameterExp, out var constExp, out var propertyExp);
var propertyType = propertyExp.Type;
Expression ConvertOrFalse <T>(bool isConvarted, T convarted) =>
!isConvarted?Expression.Constant(false) : (Expression)Expression.Equal(propertyExp, Expression.Constant(convarted, propertyExp.Type));
Expression body;
if (propertyType.IsString())
{
var containsInfo = typeof(DbFunctions).GetMethod(nameof(DbFunctions.Like), new[] { typeof(string), typeof(string), typeof(string) });
body = Expression.Call(null, containsInfo, propertyExp, ToLikeExp(value?.ToString() ?? ""), Expression.Constant(FilterDataHelper.LikeScreening.ToString()));
}
else if (propertyType == typeof(int) || propertyType == typeof(int?))
{
body = ConvertOrFalse(int.TryParse(value, out int res), res);
}
else if (propertyType == typeof(DateTime) || propertyType == typeof(DateTime?))
{
body = ConvertOrFalse(DateTime.TryParse(value, out var res), res);
}
else if (propertyType == typeof(double) || propertyType == typeof(double?))
{
body = ConvertOrFalse(double.TryParse(value, out var res), res);
}
else if (propertyType == typeof(decimal) || propertyType == typeof(decimal?))
{
body = ConvertOrFalse(decimal.TryParse(value, out var res), res);
}
else if (propertyType == typeof(float) || propertyType == typeof(float?))
{
body = ConvertOrFalse(float.TryParse(value, out var res), res);
}
else if (propertyType == typeof(byte) || propertyType == typeof(byte?))
{
body = ConvertOrFalse(byte.TryParse(value, out var res), res);
}
else if (propertyType == typeof(long) || propertyType == typeof(long?))
{
body = ConvertOrFalse(long.TryParse(value, out var res), res);
}
else if (propertyType == typeof(short) || propertyType == typeof(short?))
{
body = ConvertOrFalse(short.TryParse(value, out var res), res);
}
else if (propertyType == typeof(bool) || propertyType == typeof(bool?))
{
if (FilterDataHelper.IsTrue(value))
{
body = Expression.Equal(propertyExp, Expression.Constant(true, propertyExp.Type));
}
else if (FilterDataHelper.IsFalse(value))
{
body = Expression.Equal(propertyExp, Expression.Constant(false, propertyExp.Type));
}
else
{
body = ConvertOrFalse(bool.TryParse(value, out var res), res);
}
}
else
{
body = Expression.Constant(false);
}
return(Expression.Lambda(body, parameterExp));
}
private static ConstantExpression ToLikeExp(string value) => Expression.Constant(FilterDataHelper.ToLikeString(value));
