public Parser(IEnumerable <KeyValuePair <string, StringValues> > configParams, IQueryable <T> queryable)
{
_queryable = queryable;
_config = configParams.ToDictionary(k => k.Key, v => v.Value.First().Trim());
_type = typeof(T);
//This associates class properties with corresponding datatable configuration options
_propertyMap = (from param in _config
join prop in _type.GetProperties() on param.Value equals prop.Name
where Regex.IsMatch(param.Key, Constants.COLUMN_PROPERTY_PATTERN)
let index = Regex.Match(param.Key, Constants.COLUMN_PROPERTY_PATTERN).Groups[1].Value
let searchableKey = Constants.GetKey(Constants.SEARCHABLE_PROPERTY_FORMAT, index)
let searchable = _config.ContainsKey(searchableKey) && _config[searchableKey] == "true"
let orderableKey = Constants.GetKey(Constants.ORDERABLE_PROPERTY_FORMAT, index)
let orderable = _config.ContainsKey(orderableKey) && _config[orderableKey] == "true"
let filterKey = Constants.GetKey(Constants.SEARCH_VALUE_PROPERTY_FORMAT, index)
let filter = _config.ContainsKey(filterKey)?_config[filterKey]:string.Empty
// Set regex when implemented
select new
{
index = int.Parse(index),
map = new PropertyMap
{
Property = prop,
Searchable = searchable,
Orderable = orderable,
Filter = filter
}
}).Distinct().ToDictionary(k => k.index, v => v.map);
if (_propertyMap.Count == 0)
{
throw new Exception("No properties were found in request. Please map datatable field names to properties in T");
}
if (_config.ContainsKey(Constants.DISPLAY_START))
{
int.TryParse(_config[Constants.DISPLAY_START], out _skip);
}
if (_config.ContainsKey(Constants.DISPLAY_LENGTH))
{
int.TryParse(_config[Constants.DISPLAY_LENGTH], out _take);
}
else
{
_take = 10;
}
_sortDisabled = _config.ContainsKey(Constants.ORDERING_ENABLED) && _config[Constants.ORDERING_ENABLED] == "false";
}
private void ApplySort()
{
var sorted = false;
var paramExpr = Expression.Parameter(_type, "val");
// Enumerate the keys sort keys in the order we received them
foreach (var param in _config.Where(k => Regex.IsMatch(k.Key, Constants.ORDER_PATTERN)))
{
// column number to sort (same as the array)
int sortcolumn = int.Parse(param.Value);
// ignore disabled columns
if (!_propertyMap.ContainsKey(sortcolumn) || !_propertyMap[sortcolumn].Orderable)
{
continue;
}
var index = Regex.Match(param.Key, Constants.ORDER_PATTERN).Groups[1].Value;
var orderDirectionKey = Constants.GetKey(Constants.ORDER_DIRECTION_FORMAT, index);
// get the direction of the sort
string sortdir = _config[orderDirectionKey];
var sortProperty = _propertyMap[sortcolumn].Property;
var expression1 = Expression.Property(paramExpr, sortProperty);
var propType = sortProperty.PropertyType;
var delegateType = Expression.GetFuncType(_type, propType);
var propertyExpr = Expression.Lambda(delegateType, expression1, paramExpr);
// apply the sort (default is ascending if not specified)
string methodName;
if (string.IsNullOrEmpty(sortdir) || sortdir.Equals(Constants.ASCENDING_SORT, StringComparison.OrdinalIgnoreCase))
{
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
//Not sure if we care about the queriables that come in sorted? IOrderedQueryable does not seem to be a reliable test
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>;
}
}