How can I detect if this dictionary key exists in C#?
I am working with the Exchange Web Services Managed API, with contact data. I have the following code, which is functional, but not ideal:
foreach (Contact c in contactList)
{
string openItemUrl = "https://" + service.Url.Host + "/owa/" + c.WebClientReadFormQueryString;
row = table.NewRow();
row["FileAs"] = c.FileAs;
row["GivenName"] = c.GivenName;
row["Surname"] = c.Surname;
row["CompanyName"] = c.CompanyName;
row["Link"] = openItemUrl;
//home address
try { row["HomeStreet"] = c.PhysicalAddresses[PhysicalAddressKey.Home].Street.ToString(); }
catch (Exception e) { }
try { row["HomeCity"] = c.PhysicalAddresses[PhysicalAddressKey.Home].City.ToString(); }
catch (Exception e) { }
try { row["HomeState"] = c.PhysicalAddresses[PhysicalAddressKey.Home].State.ToString(); }
catch (Exception e) { }
try { row["HomeZip"] = c.PhysicalAddresses[PhysicalAddressKey.Home].PostalCode.ToString(); }
catch (Exception e) { }
try { row["HomeCountry"] = c.PhysicalAddresses[PhysicalAddressKey.Home].CountryOrRegion.ToString(); }
catch (Exception e) { }
//and so on for all kinds of other contact-related fields...
}
As I said, this code works. Now I want to make it suck a little less, if possible.
I can't find any methods that allow me to check for the existence of the key in the dictionary before attempting to access it, and if I try to read it (with .ToString()
) and it doesn't exist then an exception is thrown:
500
The given key was not present in the dictionary.
How can I refactor this code to suck less (while still being functional)?
Solution 1:
You can use ContainsKey
:
if (dict.ContainsKey(key)) { ... }
or TryGetValue
:
dict.TryGetValue(key, out value);
Update: according to a comment the actual class here is not an IDictionary
but a PhysicalAddressDictionary
, so the methods are Contains
and TryGetValue
but they work in the same way.
Example usage:
PhysicalAddressEntry entry;
PhysicalAddressKey key = c.PhysicalAddresses[PhysicalAddressKey.Home].Street;
if (c.PhysicalAddresses.TryGetValue(key, out entry))
{
row["HomeStreet"] = entry;
}
Update 2: here is the working code (compiled by question asker)
PhysicalAddressEntry entry;
PhysicalAddressKey key = PhysicalAddressKey.Home;
if (c.PhysicalAddresses.TryGetValue(key, out entry))
{
if (entry.Street != null)
{
row["HomeStreet"] = entry.Street.ToString();
}
}
...with the inner conditional repeated as necessary for each key required. The TryGetValue is only done once per PhysicalAddressKey (Home, Work, etc).
Solution 2:
What is the type of c.PhysicalAddresses
? If it's Dictionary<TKey,TValue>
, then you can use the ContainsKey
method.