Question

I am using the new mvc4 ajax controller template and I don’t know how to add a search to the database query that they have.

Let’s say I have a model called Article, here is what the controller contains by default:

ObjectQuery<Article> articles = (db as IObjectContextAdapter).ObjectContext.CreateObjectSet<Article>();
articles = articles.OrderBy("it." + orderBy + (desc ? " desc" : ""));

This works fine, but I am not familial with IObjectContextAdapter and I don’t know how to add a search (ie. to see if a Article contains a term.) Normally I would have something like this:

var articles = from a in db.Articles.ToList()
                           select a;
if(!String.IsNullOrEmpty(search))
{
    articles = articles.Where(a => a.Title.ToLower().Contains(search.ToLower())
                                       || a.FullArticle.ToLower().Contains(search.ToLower())
                                       || a.TagsAndKeywords.ToLower().Contains(search.ToLower()));
}
switch(orderBy)
{
    case "TimeStamp":
        if(desc)
            articles = articles.OrderByDescending(a => a.TimeStamp);
        else
            articles = articles.OrderBy(a => a.TimeStamp);
            break;
     case "Title":
     ...
}

Obviously the new way of doing this is more succinct so I would like to stick with this. I tried combining them, using the linq query to populate the var articles, but then I am not able to use the order by part, .OrderBy(“it.” + orderBy + (desc ? ” desc” : “”)).

So my question is what is the best way to search through my database? And what exactly is this .OrderBy(“it.” + orderBy + (desc ? ” desc” : “”)) doing? I’m only familial with using OrderBy with linq.

Edit

After a lot of reading I have a better understanding of what is going on, although I still can’t get this to work.

According to this it seems like I need something similar to this:

articles = articles.Where("it.Title = @searchString");

although I think this would only work if searchString matched the title exactly. While I still don’t quite understand what this is doing, I think it uses sql expressions so I thought that this may work:

articles = articles.Where("it.Title like '%@searchString%'");

But none of this worked, and I am only shooting in the dark since I am unfamiliar with this.

Answer 1

The most succinct way to query your model without changing mvc4 template code is to create an IQueryable object and query it, like this:

ObjectQuery<Article> articles = (db as IObjectContextAdapter).ObjectContext.CreateObjectSet<Article>();
articles = articles.OrderBy("it." + orderBy + ((bool)desc ? " desc" : ""));

IQueryable<Article> iArticles = articles;

if(!String.IsNullOrEmpty(search))
    iArticles = iArticles.Where(a => a.Title.Contains(search) ||
                                                  a.FullArticle.Contains(search));

Response.AppendHeader("X-Total-Row-Count", iArticles.Count().ToString());

return PartialView(iArticles.Skip(start).Take((int)itemsPerPage));

This keep the entries in the correct order, and be sure to return the new iArticles instead of the old Articles.