Priority rules possible in a query?

From what I've seen it is not possible to set the priority of different QueryExpressions in a query. Correct?

An example to illustrate it. Imagen you have the following function in a repository (generic example)

public IList<SChild> RetrieveChildrenByParentIdandChildIdList<SChild>(int parentid, IList<int> childIdList) where SChild : CoreDomainObject //which inherits from Entity<int>
{
  Query query = new Query();
  query.QueryExpression = Entity.Attribute(typeof(T).Name + "Id") == parentid;

  foreach (int id in childIdList)
  {
    query.QueryExpression |= Entity.Attribute("Id") == id;
  }
  return Repository.Find<SChild>(query);
}

 
 
In my test, this renders an sql where condition kind of like:

 WHERE
  ((WebPage.WebSiteId = 1 OR WebPage.Id = 2) OR WebPage.Id = 3)

But what I would like is naturally something like this instead:

 WHERE
  (WebPage.WebSiteId = 1 AND (WebPage.Id = 2 OR WebPage.Id = 3))

Any chance of doing this without having to construct the whole SQL query? (i.e. using QueryExpressions with priorities).

You know what... The minute after I posted this example, I realize that I could actually get my example to work easily looking at the produced sql... How typical... . Hopefully at least someone else can benefit from my example.

All I needed to do was to change the order since you wisely inserted a parenthesis in the expression:

Query query = new Query();
foreach (int id in childIdList)
{
  query.QueryExpression |= Entity.Attribute("Id") == id;
}
query.QueryExpression &= Entity.Attribute(typeof(T).Name + "Id") == parentid;
return Repository.Find<SChild>(query);

in my test this renders as desired:

WHERE
  ((WebPage.Id = 2 OR WebPage.Id = 3) AND WebPage.WebSiteId = 1)

I guess you insert the parenthesis a a suitable subexpression each time you change the condition. Still won't work for more complex scenarios, but I guess you would like to specify the whole query then anyway. 

Thanks for following up so that others who might be searching can find your solution.

John-Daniel 

Hi Tobias,

You can use parentheses in query expressions like so:

(Entity.Attribute("Id") == 1 || Entity.Attribute("Id") == 2) && Entity.Attribute("Title").Like("A%")

Additionally, you can use negation like:

!Entity.Attribute("Contributor.Id").In(41, 42)

Or:

!Entity.Attribute("ApprovedBy.Comments").Exists() 

Cheers,

Andrew. 

ehh. Embarrasing. It did'nt even come to me to try that syntax... Great however! thanks.