CODEWITHSUNDEEP
c#xml
ymcCole
ymcCole

Reputation: 103

Check if a specific Attributes exist in an Element

i need to check if a specific Attributes ConnectionInd exists in the Element of FlightSegment. If it exist, i will store the value, if it doesnt, i will move on and read the next attributes.

The following is if it exist:

<FlightSegment ArrivalDateTime="06-16T06:10" ConnectionInd="O" DepartureDateTime="2013-06-16T00:15" SmokingAllowed="false" eTicket="true">
     <Destination ... />
</FlightSegment>

And this is if it doesn't exist:

<FlightSegment ArrivalDateTime="03-27T17:35" DepartureDateTime="2013-03-27T13:30" SmokingAllowed="false" eTicket="true">
     <Destination ... />
</FlightSegment>

i'm checking it with the following code but when there's no ConnectionInd, it will throw an error saying Object reference not set to an instance of an object.

if (FlightSegment.Item(f).Attributes["ConnectionInd"].Value != "" && FlightSegment.Item(f).Attributes["ConnectionInd"] != null)
{
    string conInd = FlightSegment.Item(f).Attributes["ConnectionInd"].Value;
}

Upvotes: 1

Views: 2943

Answers (2)

abatishchev
abatishchev

Reputation: 100308

Vice versa:

First check 

FlightSegment.Item(f).Attributes["ConnectionInd"] != null

then

FlightSegment.Item(f).Attributes["ConnectionInd"].Value != ""

Otherwise if it's indeed null, you will get NullReferenceException which you're actually getting.

More efficient:

var att = FlightSegment.Item(f).Attributes["ConnectionInd"];
if (var != null)
{
    string cind = att.Value;
}

Upvotes: 1

alamatula
alamatula

Reputation: 242

There should be a method like hasAttribute or something like that that you should use instead of FlightSegment.Item(f).Attributes["ConnectionInd"].Value because if the "ConnectionInd" does not exist you are trying to get "Value" out of a null object and that will cause an exception.

Upvotes: 0

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