Resharper warns that it may be null, but will I run into problems in the future?-CodePudding

I recently converted my code to more LINQ based code. But ReSharper warns me that the FindAsync function may return null. I don't want to check for null as I'm a bit obsessed with order. Does not checking for null cause problems in the future?

One of the old methods:

public async Task<IList<Post>> GetPostsByTagIdAsync(int tagId)
{
    var posts = new List<Post>();
    var postIds = context.PostsTags
        .Where(pt => pt.TagId == tagId)
        .Select(p => p.PostId);

    foreach (var id in postIds)
        posts.Add(await context.Posts.FindAsync(id));

    return posts;
}

New version:

public async Task<IList<Post>> GetPostsByTagIdAsync(int tagId) => 
    await context.PostsTags
        .Where(pt => pt.TagId == tagId)
        .Select(p => context.Posts.FindAsync(p.PostId).Result)
        .ToListAsync();

CodePudding user response：

Both versions are ineffective. Better to ask for Posts in one database roundtrip.

public Task<IList<Post>> GetPostsByTagIdAsync(int tagId)
{
    var query = 
        from pt in context.PostsTags
        join p in context.Posts on pt.PostId equals p.Id
        where pt.TagId == tagId
        select p;

    return query.ToListAsync();
}

Also query can be simplified if you have right navigation properties

public Task<IList<Post>> GetPostsByTagIdAsync(int tagId) => 
    context.PostsTags
        .Where(pt => pt.TagId == tagId)   
        .Select(pt => pt.Post)
        .ToListAsync();

Note that, I have removed async - it will also speedup execution, because compiler do not create additional state machine for handling asynchronous operations.