Dapper QuerySingleOrDefault doesn't return null
1
Why Dapper QuerySingleOrDefault doesn't return null?
I use hard qwery.
In result I have object with default fields.
I ran this query in DB Browser for SQLite, It returned 0 rows.
public static Sensor GetSensor(string ip, string sensorName)
{
string sql = @"SELECT ip, name, invert, enable FROM DeviceAndOids AS A JOIN
DeviceForMonitoring AS B ON A.deviceForMonitoringKey=B.key JOIN
DeviceTypes AS C ON B.deviceTypeId=C.id WHERE
oidForDeviceKey IN (SELECT key FROM OidsForDevice WHERE
deviceTypeId IN (SELECT deviceTypeId FROM DeviceForMonitoring WHERE
ip = @ip) AND
name = @sensorName)";
using (IDbConnection cnn = new SQLiteConnection(LoadConnectionString()))
{
var result = cnn.QuerySingleOrDefault<Sensor>(sql, new { ip, sensorName });
return result;
}
}
c# dapper
asked Nov 20 '18 at 8:44
Дмитрий Суворов
315
|
show 7 more comments
1
Why Dapper QuerySingleOrDefault doesn't return null?
I use hard qwery.
In result I have object with default fields.
I ran this query in DB Browser for SQLite, It returned 0 rows.
public static Sensor GetSensor(string ip, string sensorName)
{
string sql = @"SELECT ip, name, invert, enable FROM DeviceAndOids AS A JOIN
DeviceForMonitoring AS B ON A.deviceForMonitoringKey=B.key JOIN
DeviceTypes AS C ON B.deviceTypeId=C.id WHERE
oidForDeviceKey IN (SELECT key FROM OidsForDevice WHERE
deviceTypeId IN (SELECT deviceTypeId FROM DeviceForMonitoring WHERE
ip = @ip) AND
name = @sensorName)";
using (IDbConnection cnn = new SQLiteConnection(LoadConnectionString()))
{
var result = cnn.QuerySingleOrDefault<Sensor>(sql, new { ip, sensorName });
return result;
}
}
c# dapper
asked Nov 20 '18 at 8:44
Дмитрий Суворов
315
As you can see in the documentation, if there's no item it will return the default (nothing), if there's one item it will return the item and if there's many items it will return a exception. So it's not returningnullbecause it's not supposed to returnnull.
– ikerbera
Nov 20 '18 at 8:47
1
@ikerbera, thanks, I was reading. Вut what is default in my case? I thought default for object is null
– Дмитрий Суворов
Nov 20 '18 at 8:54
What is the value inresult? You probably have aSensorclass variable with all it's properties at default value. ints at 0, strings at null, bools as false and so on.
– ikerbera
Nov 20 '18 at 9:00
@ikerbera I would like use if (result != null) { // do something}
– Дмитрий Суворов
Nov 20 '18 at 9:04
Can you show yourSensorclass? I'm sure we can find some property that you can check to know if you got no data.
– ikerbera
Nov 20 '18 at 9:09
|
show 7 more comments
1
1
1
Why Dapper QuerySingleOrDefault doesn't return null?
I use hard qwery.
In result I have object with default fields.
I ran this query in DB Browser for SQLite, It returned 0 rows.
public static Sensor GetSensor(string ip, string sensorName)
{
string sql = @"SELECT ip, name, invert, enable FROM DeviceAndOids AS A JOIN
DeviceForMonitoring AS B ON A.deviceForMonitoringKey=B.key JOIN
DeviceTypes AS C ON B.deviceTypeId=C.id WHERE
oidForDeviceKey IN (SELECT key FROM OidsForDevice WHERE
deviceTypeId IN (SELECT deviceTypeId FROM DeviceForMonitoring WHERE
ip = @ip) AND
name = @sensorName)";
using (IDbConnection cnn = new SQLiteConnection(LoadConnectionString()))
{
var result = cnn.QuerySingleOrDefault<Sensor>(sql, new { ip, sensorName });
return result;
}
}
c# dapper
asked Nov 20 '18 at 8:44
Дмитрий Суворов
315
Why Dapper QuerySingleOrDefault doesn't return null?
I use hard qwery.
In result I have object with default fields.
I ran this query in DB Browser for SQLite, It returned 0 rows.
public static Sensor GetSensor(string ip, string sensorName)
{
string sql = @"SELECT ip, name, invert, enable FROM DeviceAndOids AS A JOIN
DeviceForMonitoring AS B ON A.deviceForMonitoringKey=B.key JOIN
DeviceTypes AS C ON B.deviceTypeId=C.id WHERE
oidForDeviceKey IN (SELECT key FROM OidsForDevice WHERE
deviceTypeId IN (SELECT deviceTypeId FROM DeviceForMonitoring WHERE
ip = @ip) AND
name = @sensorName)";
using (IDbConnection cnn = new SQLiteConnection(LoadConnectionString()))
{
var result = cnn.QuerySingleOrDefault<Sensor>(sql, new { ip, sensorName });
return result;
}
}
c# dapper
c# dapper
asked Nov 20 '18 at 8:44
Дмитрий Суворов
315
asked Nov 20 '18 at 8:44
Дмитрий Суворов
315
asked Nov 20 '18 at 8:44
Дмитрий Суворов
315
asked Nov 20 '18 at 8:44
Дмитрий Суворов
315
asked Nov 20 '18 at 8:44
Дмитрий Суворов
315
315
As you can see in the documentation, if there's no item it will return the default (nothing), if there's one item it will return the item and if there's many items it will return a exception. So it's not returningnullbecause it's not supposed to returnnull.
– ikerbera
Nov 20 '18 at 8:47
1
@ikerbera, thanks, I was reading. Вut what is default in my case? I thought default for object is null
– Дмитрий Суворов
Nov 20 '18 at 8:54
What is the value inresult? You probably have aSensorclass variable with all it's properties at default value. ints at 0, strings at null, bools as false and so on.
– ikerbera
Nov 20 '18 at 9:00
@ikerbera I would like use if (result != null) { // do something}
– Дмитрий Суворов
Nov 20 '18 at 9:04
Can you show yourSensorclass? I'm sure we can find some property that you can check to know if you got no data.
– ikerbera
Nov 20 '18 at 9:09
|
show 7 more comments
As you can see in the documentation, if there's no item it will return the default (nothing), if there's one item it will return the item and if there's many items it will return a exception. So it's not returningnullbecause it's not supposed to returnnull.
– ikerbera
Nov 20 '18 at 8:47
1
@ikerbera, thanks, I was reading. Вut what is default in my case? I thought default for object is null
– Дмитрий Суворов
Nov 20 '18 at 8:54
What is the value inresult? You probably have aSensorclass variable with all it's properties at default value. ints at 0, strings at null, bools as false and so on.
– ikerbera
Nov 20 '18 at 9:00
@ikerbera I would like use if (result != null) { // do something}
– Дмитрий Суворов
Nov 20 '18 at 9:04
Can you show yourSensorclass? I'm sure we can find some property that you can check to know if you got no data.
– ikerbera
Nov 20 '18 at 9:09
As you can see in the documentation, if there's no item it will return the default (nothing), if there's one item it will return the item and if there's many items it will return a exception. So it's not returning
null because it's not supposed to return null.– ikerbera
Nov 20 '18 at 8:47
As you can see in the documentation, if there's no item it will return the default (nothing), if there's one item it will return the item and if there's many items it will return a exception. So it's not returning
null because it's not supposed to return null.– ikerbera
Nov 20 '18 at 8:47
1
1
@ikerbera, thanks, I was reading. Вut what is default in my case? I thought default for object is null
– Дмитрий Суворов
Nov 20 '18 at 8:54
@ikerbera, thanks, I was reading. Вut what is default in my case? I thought default for object is null
– Дмитрий Суворов
Nov 20 '18 at 8:54
What is the value in
result? You probably have a Sensor class variable with all it's properties at default value. ints at 0, strings at null, bools as false and so on.– ikerbera
Nov 20 '18 at 9:00
What is the value in
result? You probably have a Sensor class variable with all it's properties at default value. ints at 0, strings at null, bools as false and so on.– ikerbera
Nov 20 '18 at 9:00
@ikerbera I would like use if (result != null) { // do something}
– Дмитрий Суворов
Nov 20 '18 at 9:04
@ikerbera I would like use if (result != null) { // do something}
– Дмитрий Суворов
Nov 20 '18 at 9:04
Can you show your
Sensor class? I'm sure we can find some property that you can check to know if you got no data.– ikerbera
Nov 20 '18 at 9:09
Can you show your
Sensor class? I'm sure we can find some property that you can check to know if you got no data.– ikerbera
Nov 20 '18 at 9:09
|
show 7 more comments
1 Answer
1
active
oldest
votes
1
Sensor was struct . I changed it to class
It works now
answered Nov 20 '18 at 9:45
Дмитрий Суворов
315
Note: it might have worked (renull) if you had used<Sensor?>instead of<Sensor>- however, I strongly suspect that usingstructfor something that represents a data row is probably a bad idea that could cause multiple subtle confusions
– Marc Gravell♦
Nov 20 '18 at 15:15
Maybe, I didn't understand you very well. But I changed it toclass. I didn't use<Sensor?>
– Дмитрий Суворов
Nov 20 '18 at 16:39
fair enough; changing it toclassis by far the best solution here
– Marc Gravell♦
Nov 20 '18 at 16:48
add a comment |
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1 Answer
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oldest
votes
1 Answer
1
active
oldest
votes
active
oldest
votes
active
oldest
votes
1
Sensor was struct . I changed it to class
It works now
answered Nov 20 '18 at 9:45
Дмитрий Суворов
315
Note: it might have worked (renull) if you had used<Sensor?>instead of<Sensor>- however, I strongly suspect that usingstructfor something that represents a data row is probably a bad idea that could cause multiple subtle confusions
– Marc Gravell♦
Nov 20 '18 at 15:15
Maybe, I didn't understand you very well. But I changed it toclass. I didn't use<Sensor?>
– Дмитрий Суворов
Nov 20 '18 at 16:39
fair enough; changing it toclassis by far the best solution here
– Marc Gravell♦
Nov 20 '18 at 16:48
add a comment |
1
Sensor was struct . I changed it to class
It works now
answered Nov 20 '18 at 9:45
Дмитрий Суворов
315
Note: it might have worked (renull) if you had used<Sensor?>instead of<Sensor>- however, I strongly suspect that usingstructfor something that represents a data row is probably a bad idea that could cause multiple subtle confusions
– Marc Gravell♦
Nov 20 '18 at 15:15
Maybe, I didn't understand you very well. But I changed it toclass. I didn't use<Sensor?>
– Дмитрий Суворов
Nov 20 '18 at 16:39
fair enough; changing it toclassis by far the best solution here
– Marc Gravell♦
Nov 20 '18 at 16:48
add a comment |
1
1
1
Sensor was struct . I changed it to class
It works now
answered Nov 20 '18 at 9:45
Дмитрий Суворов
315
Sensor was struct . I changed it to class
It works now
answered Nov 20 '18 at 9:45
Дмитрий Суворов
315
answered Nov 20 '18 at 9:45
Дмитрий Суворов
315
answered Nov 20 '18 at 9:45
Дмитрий Суворов
315
answered Nov 20 '18 at 9:45
Дмитрий Суворов
315
315
Note: it might have worked (renull) if you had used<Sensor?>instead of<Sensor>- however, I strongly suspect that usingstructfor something that represents a data row is probably a bad idea that could cause multiple subtle confusions
– Marc Gravell♦
Nov 20 '18 at 15:15
Maybe, I didn't understand you very well. But I changed it toclass. I didn't use<Sensor?>
– Дмитрий Суворов
Nov 20 '18 at 16:39
fair enough; changing it toclassis by far the best solution here
– Marc Gravell♦
Nov 20 '18 at 16:48
add a comment |
Note: it might have worked (renull) if you had used<Sensor?>instead of<Sensor>- however, I strongly suspect that usingstructfor something that represents a data row is probably a bad idea that could cause multiple subtle confusions
– Marc Gravell♦
Nov 20 '18 at 15:15
Maybe, I didn't understand you very well. But I changed it toclass. I didn't use<Sensor?>
– Дмитрий Суворов
Nov 20 '18 at 16:39
fair enough; changing it toclassis by far the best solution here
– Marc Gravell♦
Nov 20 '18 at 16:48
Note: it might have worked (re
null) if you had used <Sensor?> instead of <Sensor> - however, I strongly suspect that using struct for something that represents a data row is probably a bad idea that could cause multiple subtle confusions– Marc Gravell♦
Nov 20 '18 at 15:15
Note: it might have worked (re
null) if you had used <Sensor?> instead of <Sensor> - however, I strongly suspect that using struct for something that represents a data row is probably a bad idea that could cause multiple subtle confusions– Marc Gravell♦
Nov 20 '18 at 15:15
Maybe, I didn't understand you very well. But I changed it to
class. I didn't use <Sensor?>– Дмитрий Суворов
Nov 20 '18 at 16:39
Maybe, I didn't understand you very well. But I changed it to
class. I didn't use <Sensor?>– Дмитрий Суворов
Nov 20 '18 at 16:39
fair enough; changing it to
class is by far the best solution here– Marc Gravell♦
Nov 20 '18 at 16:48
fair enough; changing it to
class is by far the best solution here– Marc Gravell♦
Nov 20 '18 at 16:48
add a comment |
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As you can see in the documentation, if there's no item it will return the default (nothing), if there's one item it will return the item and if there's many items it will return a exception. So it's not returning
nullbecause it's not supposed to returnnull.– ikerbera
Nov 20 '18 at 8:47
1
@ikerbera, thanks, I was reading. Вut what is default in my case? I thought default for object is null
– Дмитрий Суворов
Nov 20 '18 at 8:54
What is the value in
result? You probably have aSensorclass variable with all it's properties at default value. ints at 0, strings at null, bools as false and so on.– ikerbera
Nov 20 '18 at 9:00
@ikerbera I would like use if (result != null) { // do something}
– Дмитрий Суворов
Nov 20 '18 at 9:04
Can you show your
Sensorclass? I'm sure we can find some property that you can check to know if you got no data.– ikerbera
Nov 20 '18 at 9:09