private List <Node> GetNeighbourNodes(string name)
{
DbDataReader reader = null;
try
{
// Some cities have multiple airports. We don't need this information here,
// so we use distinct here and get the field we need to save space and time.
reader = ApplicationDb.RunQuery($"Select DISTINCT Destination from routes.csv where Origin=\"{name}\"");
var result = new List <Node>();
while (reader.Read())
{
string neighbourName = reader["Destination"].ToString();
//If this node(airport) has already added, we don't want to create a duplicate. That breaks the algorithm.
var neighbourNode = AllNodes.FirstOrDefault(n => n.Name == neighbourName);
if (neighbourNode == null)
{
neighbourNode = new Node
{
Name = neighbourName,
};
AllNodes.Add(neighbourNode);
//We only need to process this neighbour if it hasn't already been processed.
result.Add(neighbourNode);
}
}
return(result);
}
finally
{
if (reader != null && !reader.IsClosed)
{
reader.Close();
}
// We don't close the connection, because we are going to run a lot of queries against the database
// and it is not efficient to close the connection after each query.
}
}