How to filter this data using Dictionary/List<Document>?

Question

I need some help here for my code.

I wrote this code.

List<Document> doc = SystemOperationManager.GetSalesByMemberLucene(ConfigurationManager.GetIndexPath(), memberId).ToList();

Dictionary<string, Department> _allDepartments = DepartmentManager.GetAll().ToDictionary(s => s.Id.ToString(), s => s);
Dictionary<string, User> _allUsers = UserManager.GetAll().ToDictionary(s => s.Id.ToString(), s => s);
Dictionary<string, Product> _allProducts = ProductManager.GetAll().Where(x => x.CustomType == 2).ToDictionary(s => s.Id.ToString(), s => s);

List<SystemOperation> so = doc.Select(s => new SystemOperation
{
    ObjStylist = s.Get("ObjStylist") != null ? _allUsers[s.Get("ObjStylist")] : null,
    ObjDepartment = s.Get("ObjDepartment") != null ? _allDepartments[s.Get("ObjDepartment")] : null,
    ObjProduct = s.Get("ObjProduct") != null ? _allProducts[s.Get("ObjProduct")] : null
    //TotalPointsCollected = decimal.Parse(s.Get("TotalPointsCollected")),
    //PointsAccumulated = decimal.Parse(s.Get("PointsAccumulated"))
}).ToList();

_result = so;
rgList.DataSource = _result;
rgList.DataBind();

when I run the code it say it has this error.

An exception of type 'System.Collections.Generic.KeyNotFoundException' occurred in mscorlib.dll but was not handled in user code

Additional information: The given key was not present in the dictionary.

Anyone can help me fix it?

Answer 1

given the exception you mentioned i suspect the calls to the dictionaries should be checked before you try to access them, so instead of

_allUsers[s.Get("ObjStylist")]

you could try

_allUsers.ContainsKey(s.Get("ObjStylist")) ? _allUsers[s.Get("ObjStylist")] : null

the same goes for _allDepartments[s.Get("ObjDepartment")] and _allProducts[s.Get("ObjProduct")] .

Answer 2

The problem is, that you're trying to lookup for a key that doesn't exists in the dictionary. For example: _allUsers[s.Get("ObjStylist")] if s.Get("ObjStylist") contains a nonexisting key, you'll get this error.

Therefor a TryGetValue() method of a dictionary is very usefull, because you're only looking up the key ones (instead of using Contains() and dict[key] )

You could create a lookup function which returns the value is it exists (this generic function will work on all dictionaries)

(this example is not tested and might need some tweaks)

private T LookupData<T>(Dictionary<string, T> dict, string key)
{
    if(key == null)
        return null;

    T result;

    if(dict.TryGetValue(key, out result))
        return result;
    else
        return null;

}



List<Document> doc = SystemOperationManager.GetSalesByMemberLucene(ConfigurationManager.GetIndexPath(), memberId).ToList();

Dictionary<string, Department> _allDepartments = DepartmentManager.GetAll().ToDictionary(s => s.Id.ToString(), s => s);
Dictionary<string, User> _allUsers = UserManager.GetAll().ToDictionary(s => s.Id.ToString(), s => s);
Dictionary<string, Product> _allProducts = ProductManager.GetAll().Where(x => x.CustomType == 2).ToDictionary(s => s.Id.ToString(), s => s);

List<SystemOperation> so = doc.Select(s => new SystemOperation
{
    ObjStylist = LookupData<User>(_allUsers, s.Get("ObjStylist")),
    ObjDepartment = LookupData<Department>(_allDepartments, s.Get("ObjDepartment")),
    ObjProduct = LookupData<Product>(_allProducts, s.Get("ObjProduct"))
    //TotalPointsCollected = decimal.Parse(s.Get("TotalPointsCollected")),
    //PointsAccumulated = decimal.Parse(s.Get("PointsAccumulated"))
}).ToList();

_result = so;
rgList.DataSource = _result;
rgList.DataBind();