I would Like to sort the keywords by its sort property. I have a one-many relationship between page -> keyword.
Question: If I perform a comprehension query as:
IEnumerable<page> query = from p in contxt.pages where p.ID == myId select p;
IEnumerable<page> pge = query.First();
Could I expect a single page record set with all the page’s properties and one keyword collection?
My understanding is since there exist a one-many relationship, I don’t have to perform a join. The Linq to Entity framework should have knowledge of this relationship, and return a collection.
So this is my understanding, so when I try to sort on keyword开发者_运维技巧.sort, the keyword is out of scope:
IEnumerable<page> query = from p in contxt.pages where p.ID == myId
orderby p.keywords. select p;
Utilizing the above understanding I thought the query is incorrect because keywords is returned as a collection, so I must perform a sort as follows:
PageKeywords pageKeywords = new PageKeywords();
Keywords keywords;
IEnumerable<page> query = from p in contxt.pages
where p.ID == vals.pageId select p;
page pge = query.First();
pageKeywords.keywords = new List<Keywords>();
pageKeywords.id = pge.ID;
pageKeywords.description = pge.descp;
pageKeywords.title = pge.title;
pageKeywords.showTitle = pge.showTitle;
pageKeywords.keywords = pge.keywords.OrderBy(k => k.sort);
foreach (var item in pageKeywords.keywords)
{
keywords = new Keywords();
keywords.id = item.id;
keywords.name = item.name;
keywords.sort = item.sort;
pageKeywords.keywords.Add(keywords);
}
However this did not work. The keywords were not sorted by sort? The code above does work, however I need the keywords to be sorted by sort property. The keywords collection isn't being sorted.
I also tried:
pageKeywords.keywords.Sort((x, y) => int.Compare(x.sort, y.sort));
Which did not work.
I have tried to understand, but I am missing something? Any suggestions would be appreciable.
Try this:
var query = from p in contxt.Pages
where p.ID == vals.PageId
select new PageKeywords
{
Id = pge.Id,
Description = pge.Descp,
Title = pge.Title,
ShowTitle = pge.ShowTitle,
Keywords = pge.Keywords.OrderBy(k => k.sort)
};
OrberBy returns a new enumerable - it does not change the source: http://msdn.microsoft.com/en-us/library/bb534966.aspx
Also, you want to sort by a property of keywords, a page may have many keywords, you need to choose one (e.g. minimum one).
Try:
IEnumerable<page> query = context.pages // Pages
.Where(p => p.ID == myId) // Filtered by id
// Sort by minimum sort value of all keywords of page
.OrderBy(p.Keywords.Select(keyword => keyword.sort).Min());
Also, using .NET's guidelines for names is recommended (e.g. properties should be PascalCase and not camelCase).
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