private IQueryable <T> ApplySort(IQueryable <T> queryable, AdvancedQueryRequest request)
{
var sorted = false;
var paramExpr = Expression.Parameter(_type, "val");
foreach (var param in request.Sorted)
{
if (!_propertyMap.ContainsKey(param.Id.ToLower()) || !_propertyMap[param.Id.ToLower()].Orderable)
{
continue;
}
var sortProperty = _propertyMap[param.Id.ToLower()].Property;
var expression1 = Expression.Property(paramExpr, sortProperty);
var propType = sortProperty.PropertyType;
var delegateType = Expression.GetFuncType(_type, propType);
var propertyExpr = Expression.Lambda(delegateType, expression1, paramExpr);
string methodName;
if (!param.Desc)
{
methodName = sorted ? "ThenBy" : "OrderBy";
}
else
{
methodName = sorted ? "ThenByDescending" : "OrderByDescending";
}
queryable = typeof(Queryable).GetMethods().Single(
method => method.Name == methodName &&
method.IsGenericMethodDefinition &&
method.GetGenericArguments().Length == 2 &&
method.GetParameters().Length == 2)
.MakeGenericMethod(_type, propType)
.Invoke(null, new object[] { queryable, propertyExpr }) as IOrderedQueryable <T>;
sorted = true;
}
//Linq to entities needs a sort to implement skip
if (!sorted)
{
var firstProp = Expression.Property(paramExpr, _propertyMap.First().Value.Property);
var propType = _propertyMap.First().Value.Property.PropertyType;
var delegateType = Expression.GetFuncType(_type, propType);
var propertyExpr = Expression.Lambda(delegateType, firstProp, paramExpr);
queryable = typeof(Queryable).GetMethods().Single(method =>
method.Name == "OrderBy" &&
method.IsGenericMethodDefinition &&
method.GetGenericArguments().Length == 2 &&
method.GetParameters().Length == 2)
.MakeGenericMethod(_type, propType)
.Invoke(null, new object[] { queryable, propertyExpr }) as IOrderedQueryable <T>;
}
return(queryable);
}
private Expression <Func <T, bool> > GenerateEntityFilter(AdvancedQueryRequest request)
{
var paramExpression = Expression.Parameter(_type, "val");
List <MethodCallExpression> searchProps = new List <MethodCallExpression>();
var modifier = new ModifyParam(paramExpression);
foreach (var filtered in request.Filtered)
{
if (!_propertyMap.ContainsKey(filtered.Id.ToLower()) || !_propertyMap[filtered.Id.ToLower()].Orderable)
{
continue;
}
var propMap = _propertyMap[filtered.Id.ToLower()];
var prop = propMap.Property;
var isString = prop.PropertyType == typeof(string);
var hasCustom = _converters.ContainsKey(prop.Name);
if ((!prop.CanWrite || !propMap.Searchable || (_convertable.All(t => t != prop.PropertyType) && !isString)) && !hasCustom)
{
continue;
}
Expression propExp = Expression.Property(paramExpression, prop);
if (hasCustom)
{
propExp = modifier.Visit(_converters[prop.Name]);
}
else if (!isString)
{
var toString = prop.PropertyType.GetMethod("ToString", Type.EmptyTypes);
propExp = Expression.Call(propExp, toString);
}
var toLower = Expression.Call(propExp, typeof(string).GetMethod("ToLower", Type.EmptyTypes));
var searchExpression = Expression.Constant(filtered.Value.ToLower());
searchProps.Add(Expression.Call(toLower, typeof(string).GetMethod("Contains"), searchExpression));
}
var propertyQuery = searchProps.ToArray();
if (propertyQuery.Length == 0)
{
return(x => true);
}
Expression compoundExpression = propertyQuery[0];
for (int i = 1; i < propertyQuery.Length; i++)
{
compoundExpression = Expression.Or(compoundExpression, propertyQuery[i]);
}
return(Expression.Lambda <Func <T, bool> >(compoundExpression, paramExpression));
}
public static Task <AdvancedQueryPage <T> > PageAsync <T>(this IQueryable <T> query, AdvancedQueryRequest request) where T : class
{
return(new AdvancedQueryParser <T>().ParseAsync(query, request));
}
public async Task <AdvancedQueryPage <T> > ParseAsync(IQueryable <T> queryable, AdvancedQueryRequest request)
{
var page = new AdvancedQueryPage <T>();
var filteredQuery = ApplySort(queryable, request)
.Where(GenerateEntityFilter(request));
var count = await filteredQuery.CountAsync();
if (request.PageSize == 0)
{
page.PageCount = 1;
page.Data = filteredQuery.ToList();
return(page);
}
page.PageCount = (int)Math.Ceiling((double)count / request.PageSize);
page.Data = filteredQuery
.Skip(request.PageSize * request.Page)
.Take(request.PageSize)
.ToList();
return(page);
}