Dynamic OrderBy

[Johan Nordberg]

I have a query where I don't know the sort order at compile time. I'd like to pass the sorting as a parameter to the method.

var sort = <please help me create a dynamic sort expression>;

var query = DocumentSession.Query<Post>()
                .OrderByDescending(sort)
                .Skip(start)
                .Take(count)
                .ToList();

How can I init the sort variable and .OrderByDescending to set the sort order at runtime?

[Ryan Heath]

var query = DocumentSession.Query<Post>()

.Skip(start)
.Take(count);

switch(...)
{
case ...: query = query.OrderByDescending(...); break;
case ...: query = query.OrderByDescending(...); break;
case ...: query = query.OrderByDescending(...); break;
...
}

var list = query.ToList();

Does this helps?

// Ryan

[Johan Nordberg]

Is is not possible to create linq expression dynamicly? 

[Ryan Heath]

What do you mean?

The sample code should get you started ...
based on your method input you can attach a different orderby.

// Ryan

[Johan Nordberg]

Yes, but let's say my model has 20 properties that I could sort on, both asc and desc. That would be pretty big switch statement... 

What I was thinking that maybe there was a more dynamic way to say x => x.ProperyName, like ParseExpression<MyType>(string propertyName) and that would be something you could pass into OrderByAscending or OrderByDescending.

// Johan

[Mauro Servienti]

you can start from here:

http://www.albahari.com/nutshell/predicatebuilder.aspx

and built your one predicate builder for OrderBy

.m

[Ayende Rahien]

You can use the untyped DocumentSession.Query<...>().OrderBy(string) method

[Chris Marisic]

I'm going to need to remember this, I just recently did some shitty switch case code to do orderbys instead of trying to build predicates dynamically.

[Johan Nordberg]

Thanks exactly what I was looking for, but I cant find any overload for OrderBy that accepts a string. Am I missing some using statement? In which namespace is this defined?

[Ayende Rahien]

It is not on IQueryable, it is on LuceneQuery

[Johan Nordberg]

Thanks, sorting works great, but my where filters dont work. Every document is returned. What am I doing wrong?

Properties is defined as Dictionary<string, string>.

var query = DocumentSession.Advanced.LuceneQuery<Post>()
                .Include(x => x.UserId)
                .Statistics(out stats)
                .WhereEquals("IsOnline", true)
                .WhereEquals("Country", country)
                .WhereEquals("Properties." + propertyName, propertyValue)
                .OrderBy(orderBy)
                .Skip(start)
                .Take(count)
                .ToList();

[Ayende Rahien]

What is sent to the server?

[Johan Nordberg]

Request # 150: GET     -    58 ms - <default>  - 200 - /indexes/dynamic/Posts?query=IsOnline%253Atrue%2520Country%253Asv%255C-se%2520Properties.Color%253Ablack&

start=0&pageSize=10&aggregation=None&sort=-Created&include=UserId

Thanks for helping me!

[Ayende Rahien]

Well,

This is the actual query being sent:

IsOnline:true Country:sv\-se Properties.Color:black

And it seems to be a good one. Can you try creating a failing test?

[Itamar Syn-Hershko]

I _think_ we should be escaping sv\-se

Can you try sending Country:sv\\-se?

[Itamar Syn-Hershko]

Or I got this completely wrong and country==sv-se

[Ayende Rahien]

I think that \- _is_ the escape, it is sv-se, proably

On Mon, Oct 17, 2011 at 1:17 PM, Itamar Syn-Hershko <ita...@hibernatingrhinos.com> wrote:

[Johan Nordberg]

It should be country=sv-se, so the escaping is done by raven I guess?!

[Ayende Rahien]

Yes, that is correct and should be done

[Matt Warren]

The query

IsOnline:true Country:sv\-se Properties.Color:black

is the same as the query below (because OR is the default if no
operator is supplied)
IsOnline:true OR Country:sv\-se OR Properties.Color:black

With your data does this query match all the records?

On Oct 17, 1:22 pm, Ayende Rahien <aye...@ayende.com> wrote:
> Yes, that is correct and should be done
>

[Johan Nordberg]

Yes, everything has IsOnline == true right now.

How should this be written to AND all filters?

[Ayende Rahien]

Where().AndAlso().Where()

[Johan Nordberg]

Thanks everyone! Got it working!