Modifying Service URLs with LINQ to Twitter
- by Joe Mayo
It’s funny that two posts so close together speak about flexibility with the LINQ to Twitter provider. There are certain things you know from experience on when to make software more flexible and when to save time. This is another one of those times when I got lucky and made the right choice up front. I’m talking about the ability to switch URLs.
It only makes sense that Twitter should begin versioning their API as it matures. In fact, most of the entire API has moved to the v1 URL at “https://api.twitter.com/1/”, except for search and trends. Recently, Twitter introduced the available and local trends, but hung them off the new v1, and left the rest of the trends API on the old URL. To implement this, I muscled my way into the expression tree during CreateRequestProcessor to figure out which trend I was dealing with; perhaps not elegant, but the code is in the right place and that’s what factories are for. Anyway, the point is that I wouldn’t have to do this kind of stuff (as much fun as it is), if Twitter would have more consistency. Having went to Chirp last week and seeing the evolution of the API, it looks like my wish is coming true. …now if they would just get their stuff together on the mess they made with geo-location and places… but again, that’s all transparent if your using LINQ to Twitter because I pulled all of that together in a consistent way so that you don’t have to.
Normally, when Twitter makes a change, code breaks and I have to scramble to get the fixes in-place. This time, in the case of a URL change, the adjustment is easy and no-one has to wait for me. Essentially, all you need to do is change the URL passed to the TwitterContext constructor. Here’s an example of instantiating a TwitterContext now:
using (var twitterCtx = new TwitterContext(auth, "https://api.twitter.com/1/", "https://search.twitter.com/"))
The third parameter constructor is the SearchUrl, which is used for Search and Trend APIs. You probably know what’s coming next; another constructor, but with the SearchUrl parameter set to the new URL as follows:
using (var twitterCtx = new TwitterContext(auth, "https://api.twitter.com/1/", "https://api.twitter.com/1/"))
One consequence of setting the URL this way is that you set the URL for both Trends and Search. Since Search is still using the old URL, this is going to break for Search queries. You could always instantiate a special TwitterContext instance for Search queries, with the old URL set. Alternatively, you can use the TwitterContext’s SearchUrl property. Here’s an example:
twitterCtx.SearchUrl = "https://api.twitter.com/1/";
var trends =
(from trend in twitterCtx.Trends
where trend.Type == TrendType.Daily &&
trend.Date == DateTime.Now.AddDays(-2).Date
select trend)
.ToList();
Notice how I set the SearchUrl property just-in-time for the query. This allows you to target the URL for each specific query. Whichever way you prefer to configure the URL, it’s your choice.
So, now you know how to set the URL to be used for Trend queries and how to prevent whacking your Search queries. I’ll be updating the Trend API to use same URL as all other APIs soon, so the only API left to use the SearchUrl will be Search, but for the short term, it’s Trends and Search. Until I make this change, you’ll have a viable work-around by setting the URL yourself, as explained above.
These were the Search and Trend URLs, but you might be curious about the second parameter of the TwitterContext constructor; that’s the URL for all other APIs (the BaseUrl), except for Trend and Search. Similarly, you can use the TwitterContext’s BaseUrl property to set the BaseUrl. Setting the BaseUrl can be useful when communicating with other services.
In addition to Twitter changing URLs, the Twitter API has been adopted by other companies, such as Identi.ca, Tumblr, and WordPress. This capability lets you use LINQ to Twitter with any of these services. This is a testament to the success of the Twitter API and it’s popularity. No doubt we’ll have hills and valleys to traverse as the Twitter API matures, but hopefully there will be enough flexibility in LINQ to Twitter to make these changes as transparent as possible for you.
@JoeMayo
