Just in case you don't understood the aggregate thing, and how to use the
result..
var parameter = Expression.Parameter(typeof(TEntity), "p");
var body = parameter;
foreach(var subProperty in propertyAccess.Split('.'))
{
body = Expression.Property(body, subProperty);
}
var sortExpression = Expression.Lambda<Action<TEntity>>(body, parameter);
var result = source.OrderBy(sortExpression);
(actually the aggregate thing is resharper magic)
2010/3/8 José F. Romaniello <[email protected]>
> let me show you another way.
>
> Lets said that you have a grid to show Albums and you have one column with
> this bindingpath: "Artist.Country.Name"
> then you want to sort the grid when the user press the column header, in
> the database or memory... So you want this to be technology independent.
>
> So I do this:
>
> var parameter = Expression.Parameter(typeof(TEntity), "p");
> var body = (MemberExpression)
> propertyAccess.Split('.').Aggregate(parameter, Expression.Property);
> Expression.Lambda<Action<TEntity>>(body, parameter);
>
>
> where TEntity is Album
> and propertyAccess is the binding path of the column.
>
> again, Why do you need dynamic linq?
>
>
>
> 2010/3/7 Diego Mijelshon <[email protected]>
>
>> José,
>>
>> Dynamic Linq has some legitimate uses.
>> In the app we're working on, for example, clicking on any column on a WPF
>> grid sorts by that column via NH. Instead of doing something by hand, we
>> just grab the binding path, and apply a dynamic OrderBy to the source (NH
>> IQueryable). The Dynamic LINQ library takes care of parsing the path into
>> all the corresponding expressions.
>>
>> Diego
>>
>>
>> On Sun, Mar 7, 2010 at 14:05, José F. Romaniello
>> <[email protected]>wrote:
>>
>>> dynamic linq is a ***.
>>> Why do you wan that? Who defines that string?
>>>
>>> instead of concatenating strings to make your query you can create an
>>> expression with:
>>>
>>> Expression.Parameter()
>>> Expression.Property()
>>> Expression....
>>>
>>>
>>>
>>>
>>> 2010/3/7 Stefan Wenig <[email protected]>
>>>
>>> Hi
>>>>
>>>> so you want to use LINQ 2 objects (the IEnumerable version), not LINQ
>>>> 2 NH?
>>>> In any case, Dynamic LINQ only provides parsing of Where etc. clauses,
>>>> not entire queries. So this is only a complete solution if the
>>>> structure of your query is alreay known at compile time and users just
>>>> enter conditions etc. DL is not using lamda notation, BTW, so I don't
>>>> know how multiple sources are referred to in more complex queries
>>>> (might not be supported at all, need to check).
>>>> I'd try dynamic compilation, that shouldn't be too hard. (CodeDOM can
>>>> help with compilation and even generate boiler plate code for any
>>>> supported language.) Use the #line directive to get useful error
>>>> messages. You have to take care of assembly loading though, and you
>>>> can't unload them anymore. (There's been talk about straight type/
>>>> assembly unloading support in .NET 4, but I didn't check). Using
>>>> separate AppDomains is going to be a problem, especially if you want
>>>> to execute the query in memory (you can hardly pass the entire object
>>>> graph via remoting/serialization). Using Mono C# to compile to dynamic
>>>> methods would be cool, but it'd be a lot of work, and would not work
>>>> for queries that generate types (anonymous types or - implicitly - via
>>>> transparent identifiers).
>>>>
>>>> VB10 was rumored to have REPL-support, so if you can wait for that and
>>>> accept VB syntax, check out the RC. If that's not an option and you
>>>> need unloading, I'd look at HQL again.
>>>>
>>>> Let us know how you solved that one! Support for user-provided LINQ is
>>>> definitely an interesting feature.
>>>>
>>>> Stefan
>>>>
>>>> On 6 Mrz., 16:32, CassioT <[email protected]> wrote:
>>>> > Because I already have the object graph and I don't want to hit the
>>>> > database again.
>>>> >
>>>> > I used a DAO to get the first object only to give you a scenario, but
>>>> > the real code is not like that.
>>>> >
>>>> > But even if it was the case I would chose LINQ. The string will be
>>>> > written in the UI and I don't want HQL (or even SQL) in the UI. I want
>>>> > it to be technology independent. That's why LINQ to NH is so waited.
>>>> >
>>>> > Thanks all replies.
>>>> >
>>>> > On Mar 5, 7:09 pm, Mohamed Meligy <[email protected]> wrote:
>>>> >
>>>> >
>>>> >
>>>> > > If you are using strings, why not use HQL directly? Then life should
>>>> be
>>>> > > pretty much more straight forward.
>>>> > > Dynamic LINQ library (referred by Angel) is also great, and many
>>>> tried it
>>>> > > successfully.
>>>> >
>>>> > > --
>>>> > > Mohamed Meligy
>>>> > > Senior Developer, Team Lead Backup (.Net Technologies - TDG -
>>>> Applications)
>>>> > > Injazat Data Systems
>>>> > > P.O. Box: 8230 Abu Dhabi, UAE.
>>>> >
>>>> > > Phone: +971 2 6992700
>>>> > > Direct: +971 2 4045385
>>>> > > Mobile: +971 50 2623624, +971 55 2017 621
>>>> >
>>>> > > E-mail: [email protected]
>>>> > > Weblog:http://gurustop.net
>>>> >
>>>> > > On Fri, Mar 5, 2010 at 9:53 PM, Angel Java Lopez <
>>>> [email protected]>wrote:
>>>> >
>>>> > > > Hi people!
>>>> >
>>>> > > > Cassio, check the additional code described in
>>>> >
>>>> > > >
>>>> http://weblogs.asp.net/scottgu/archive/2008/01/07/dynamic-linq-part-1.
>>>> ..
>>>> >
>>>> > > > I use some of this in my example
>>>> > > >
>>>> http://ajlopez.wordpress.com/2009/01/30/dynamic-expressions-example/
>>>> > > > there are more links there, pointing to other implementation
>>>> >
>>>> > > > There is a Codeplex project, simplifyng the build of a
>>>> QueryProvider, not
>>>> > > > related with your question, but it could be interesting. I guess
>>>> NHibernate
>>>> > > > devs were using it to build the new Linq implemented in NH
>>>> >
>>>> > > > Angel "Java" Lopez
>>>> > > >http://www.ajlopez.com
>>>> > > >http://twitter.com/ajlopez
>>>> >
>>>> > > > On Fri, Mar 5, 2010 at 4:40 PM, Ken Egozi <[email protected]>
>>>> wrote:
>>>> >
>>>> > > >> you could either look up c# parser and lexer codes, and tweak to
>>>> your
>>>> > > >> needs. Maybe look at Mono's c# compiler.
>>>> > > >> that is however non trivial work.
>>>> >
>>>> > > >> you can also wrap the text with a valid c# class and method
>>>> declarations,
>>>> > > >> then use a CodeDomProvider.CompileAssemblyFromSource() to get an
>>>> assembly,
>>>> > > >> lookup your new type, and invoke the new method.
>>>> >
>>>> > > >> On Fri, Mar 5, 2010 at 9:23 PM, CassioT <[email protected]>
>>>> wrote:
>>>> >
>>>> > > >>> Hi all. This is an NH off topic but it is C# and programming
>>>> anyway.
>>>> >
>>>> > > >>> Let's suppose:
>>>> >
>>>> > > >>> var blog = dao.GetBlog(1); //Blog has posts
>>>> >
>>>> > > >>> string s = "blog.Posts.Sum(p => p.NumOfVisitors)";
>>>> >
>>>> > > >>> or
>>>> >
>>>> > > >>> string s = "Posts.Sum(p => p.NumOfVisitors)"; // considering
>>>> blog as
>>>> > > >>> the root object
>>>> >
>>>> > > >>> What is the best way to translate this string in code
>>>> dynamically?
>>>> > > >>> This is only a simple example but it is near of what I want.
>>>> >
>>>> > > >>> Thanks.
>>>> >
>>>> > > >>> --
>>>> > > >>> You received this message because you are subscribed to the
>>>> Google Groups
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>>>> > > >>> To unsubscribe from this group, send email to
>>>> > > >>> [email protected]<nhusers%[email protected]>
>>>> <nhusers%[email protected]<nhusers%[email protected]>>
>>>> > > >>> .
>>>> > > >>> For more options, visit this group at
>>>> > > >>>http://groups.google.com/group/nhusers?hl=en.
>>>> >
>>>> > > >> --
>>>> > > >> Ken Egozi.
>>>> > > >>http://www.kenegozi.com/blog
>>>> > > >>http://www.delver.com
>>>> > > >>http://www.musicglue.com
>>>> > > >>http://www.castleproject.org
>>>> > > >>http://www.idcc.co.il-הכנס הקהילתי הראשון למפתחי דוטנט - בואו
>>>> בהמוניכם
>>>> >
>>>> > > >> --
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>>>> ausblenden -
>>>> >
>>>> > - Zitierten Text anzeigen -
>>>>
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