Check existence of a record before returning resultset in LINQ to SQL
I'm looking for a simple solution to replace my standardized junk way of validating whether a record exists before attempting to retrieve the data. Currently, whenever one of my methods are called, I do something to the effect of...
private Record DoSomething(int id)
{
if(data.Records.Count(q=>q.Id==id) > 0)
{
return data.Records.First(q=>q.Id==id);
}
return null;
}
...w开发者_运维技巧here I always check the count of the records to determine the existence of a record. There has to be a more "elegant" way of doing this, without calling the database twice. Is there a way?
There are a lot of clean ways to handle this. If you want the first Record
corresponding to id
you can say:
Record record = data.Records.FirstOrDefault(r => r.Id == id);
if(record != null) {
// record exists
}
else {
// record does not exist
}
If you only want to know if such a Record
exists:
return data.Records.Any(r => r.Id == id); // true if exists
If you want a count of how many such Record
exists:
return data.Records.Count(r => r.Id == id);
If you want an enumeration (IEnumerable<Record>
) of all such Record
:
return data.Records.Where(r => r.Id == id);
Record record = data.Records.FirstOrDefault(q => q.Id == id);
return record;
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