Re: How to process datareader nulls coming from datareader?

[=?UTF-8?B?QXJuZSBWYWpow7hq?=]

JB wrote:

I am using a datareader to reader a table. The table may have some null
values in it. The thing is that I need to process the row whether the field
has null values in it or not. The "Swim" field in this table will have null
values in it. The problem is that when I try to read the field with a null
value I get the error message stating:

"unable to cast object of type 'System.DBNull' to type 'System.String'.

reader =
selectCommand.ExecuteReader(CommandBehavior.Single Result);
while (reader.Read())
{
WillUsedList WillUsed = new WillUsedList((int)reader["PoolLoc
"],(string)reader["Swims"]);

if(!reader.IsDBNull(swimcol))
{
// use (string)reader[swimcol]
}
else
{
// use some default value maybe null
}

WillUsed. PoolAddr = (int)reader["PoolLoc"];
WillUsed. PollHeat = (string)reader["Swims"];
nuList.Add(WillUsed.PoolAddr);
nuList.Add(WillUsed. PollHeat);
}
reader.Close();

Arne

[=?Utf-8?B?SkI=?=]

Hello Arne

Actually the error points to the module where the property is set and
not when the column is read from the datareader. But if you say it is a
datareader problem, if I am reading a table with lets say for example 25
columns does that mean write 25 "if" statements (one for each column) or is
it that the datareader is reading the null column and when it hits the
propery set module there is some way to deal with it there?
--
JB
"Arne Vajhøj" wrote:

JB wrote:

I am using a datareader to reader a table. The table may have some null
values in it. The thing is that I need to process the row whether the field
has null values in it or not. The "Swim" field in this table will have null
values in it. The problem is that when I try to read the field with a null
value I get the error message stating:

"unable to cast object of type 'System.DBNull' to type 'System.String'.

reader =
selectCommand.ExecuteReader(CommandBehavior.Single Result);
while (reader.Read())
{
WillUsedList WillUsed = new WillUsedList((int)reader["PoolLoc
"],(string)reader["Swims"]);

if(!reader.IsDBNull(swimcol))
{
// use (string)reader[swimcol]
}
else
{
// use some default value maybe null
}

WillUsed. PoolAddr = (int)reader["PoolLoc"];
WillUsed. PollHeat = (string)reader["Swims"];
nuList.Add(WillUsed.PoolAddr);
nuList.Add(WillUsed. PollHeat);
}
reader.Close();

Arne