private static Expression<Func<Student, bool>>
ProcessCriterias(List<SearchCriteria.StringValue> clist) {
return clist.Select(item => ProcessCriteria(item)).Aggregate(Or);
}
private static Expression<Func<T, bool>> Or<T>(Expression<Func<T, bool>>
expr1,
Expression<Func<T, bool>>
expr2) {
var invokedExpr = Expression.Invoke(expr2,
expr1.Parameters.Cast<Expression>());
return Expression.Lambda<Func<T, bool>>
(Expression.OrElse(expr1.Body, invokedExpr), expr1.Parameters);
}
This is probably not the most efficient way to do any of this. The
criteria API would be considerably better I think.
If you do go this route you may also want an and function:
private static Expression<Func<T, bool>> And<T>(Expression<Func<T,
bool>> expr1,
Expression<Func<T, bool>>
expr2) {
var invokedExpr = Expression.Invoke(expr2,
expr1.Parameters.Cast<Expression>());
return Expression.Lambda<Func<T, bool>>
(Expression.AndAlso(expr1.Body, invokedExpr), expr1.Parameters);
}
lukefrice wrote:
> Basically I am doing it like this.
>
> private static Expression<Func<Student, bool>> ProcessCriteria
> (SearchCriteria.StringValue criteria)
> {
> if (criteria.FieldName == "FirstName") { return
> BuildFirstName(criteria.Value, criteria.Comparer); }
> }
>
> private static Expression<Func< Student, bool>> BuildFirstName(string
> value, StringFilterType comparer)
> {
> switch (comparer)
> {
> case StringFilterType.Contains:
> return (s) => s.FirstName.Contains(value);
> case StringFilterType.EndsWith:
> return (s) => s.FirstName.EndsWith(value);
> case StringFilterType.Equals:
> return (s) => s.FirstName == value;
> default:
> return (s) => s.FirstName.StartsWith(value);
> }
> }
>
> This way when i call into the class containing this, i can pass in
> just the field name and the comparer type and it knows which set of
> comparers.
> After this I am combining the Expressions together with this inside my
> dataProvider.
>
> var query = _session.Linq<Student>().AsQueryable();
> query = StudentSearchCriteriaManager.BuildQuery(query,
> criteria);
> return query.ToList();
>
> and here is part of the BuildQuery method used to put them together
>
> result = result.Where(ProcessCriteria((SearchCriteria.NumericValue)
> item));
> break;
>
>
>
> On Aug 10, 5:09 pm, John Rayner <[email protected]> wrote:
>
>> Create your own Disjunction object?
>>
>> Disjunction disj = new Disjunction();
>> for(int i = 0; i < numRestrictions; i++)
>> disj.Add( Restrictions.Eq( .... ) );
>>
>> If not this, then please give an example of the sort of code you'd
>> like to write.
>>
>> Cheers,
>> John
>>
>> On Aug 10, 8:15 pm, lukefrice <[email protected]> wrote:
>>
>>
>>
>>
>>> I do understand, but I am looking more for something like
>>> PredicateBuilder. Is there anything like that that can be used with
>>> NHibernate?
>>>
>>> On Aug 10, 1:23 pm, Tuna Toksoz <[email protected]> wrote:
>>>
>>>> this is programatic, you have as much flexibility as your imagination.
>>>> ICriterion x=something;
>>>> if(something)
>>>> x=Restrictions.Or(x,anotherRestriction);
>>>>
>>>> if(another)
>>>> x=Restrictions.Or(x,anotherthinghere);
>>>>
>>>> Can I tell what I mean?
>>>>
>>>> Tuna Toksöz
>>>> Eternal sunshine of the open source mind.
>>>>
>>>> http://devlicio.us/blogs/tuna_toksozhttp://tunatoksoz.comhttp://twitt...
>>>>
>>>> On Mon, Aug 10, 2009 at 9:20 PM, lukefrice <[email protected]> wrote:
>>>>
>>>>> way to combine some of them as OR's, or po- Hide quoted text -
>>>>>
>>> - Show quoted text -
>>>
> >
>
>
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