{"id":126,"date":"2026-07-21T13:13:34","date_gmt":"2026-07-21T13:13:34","guid":{"rendered":"https:\/\/www.ivanjurina.com\/?p=126"},"modified":"2026-07-21T13:13:35","modified_gmt":"2026-07-21T13:13:35","slug":"what-a-2019-api-client-teaches-you-about-modern-net","status":"publish","type":"post","link":"https:\/\/www.ivanjurina.com\/index.php\/2026\/07\/21\/what-a-2019-api-client-teaches-you-about-modern-net\/","title":{"rendered":"what a 2019 api client teaches you about modern .net"},"content":{"rendered":"\n

i’ve been playing with SerpApi<\/a> lately. nice service. one GET request and you get structured json for google, bing, maps, news, shopping and about a hundred other search surfaces. captchas and layout changes handled for you. their python and ruby stories are strong. their .net story is a time capsule.<\/p>\n\n\n\n

the official google-search-results-dotnet<\/code><\/a> package was written around 2019 and it shows. Hashtable<\/code> parameters. Newtonsoft.Json. a synchronous api that blocks on Task.Result<\/code>. not a knock on SerpApi, every company has a long tail of sdks. but it makes a great case study. the distance between “working 2019 c#” and “good 2026 c#” is exactly the stuff that bites people in production. so i did two things. sent a set of prs to the official library, and built a modern client from scratch (serpapi-dotnet<\/a>). here’s what changed and why it matters.<\/p>\n\n\n\n

1. sync-over-async is a deadlock waiting for a synchronization context<\/h2>\n\n\n\n

the original core looks like this:<\/p>\n\n\n\n

Task<string> queryTask = createQuery(uri, parameter, jsonEnabled);\nqueryTask.ConfigureAwait(true);   \/\/ does nothing here, by the way\nreturn queryTask.Result;\n<\/code><\/pre>\n\n\n\n
two problems. first, Task.Result<\/code> wraps any failure in an AggregateException<\/code>. callers catch (SerpApiSearchException)<\/code> and miss. second, blocking on a task that resumes on a captured context deadlocks classic asp.net and ui apps. the ConfigureAwait(true)<\/code> on a task variable (not an await) is a no-op. a hint that the intent was understood but the mechanics weren’t.<\/p>\n\n\n\n
the fix when you must keep a sync api for compatibility: GetAwaiter().GetResult()<\/code>, which rethrows the original exception, plus ConfigureAwait(false)<\/code> on every await inside the library. the real fix: expose GetJsonAsync(CancellationToken)<\/code> and let callers be async end to end. my pr does both without breaking the existing surface.<\/p>\n\n\n\n
2. catch (Exception ex) => throw new X(ex.ToString())<\/code> destroys the stack<\/h2>\n\n\n\n
the original wraps every failure like this:<\/p>\n\n\n\n
catch (Exception ex)\n{\n    throw new SerpApiSearchException(ex.ToString());\n}\n<\/code><\/pre>\n\n\n\n
stringifying the exception into a message means no InnerException<\/code>, no type to catch on, and cancellation gets swallowed into a generic error. the modern pattern: let OperationCanceledException<\/code> flow untouched, wrap transport errors with the original as InnerException<\/code>, and carry the http status code on your exception type. callers can then tell a 401 from a 429 without parsing strings.<\/p>\n\n\n\n
3. Hashtable<\/code> to typed request with an escape hatch<\/h2>\n\n\n\n
Hashtable<\/code> is pre-generics .net. the interesting design question is what replaces it, because SerpApi has dozens of engines with different parameters. a rigid typed model can’t cover them all. a plain Dictionary<string,string><\/code> gives up on discoverability. the answer is both:<\/p>\n\n\n\n
var request = new SearchRequest\n{\n    Engine = SearchEngine.GoogleNews,\n    Query = \"dotnet 9\",\n    Location = \"Prague, Czechia\",\n    AdditionalParameters = { [\"so\"] = \"1\" },   \/\/ anything engine-specific\n};\n<\/code><\/pre>\n\n\n\n
common parameters are typed and documented. everything else passes through. same philosophy on the response side: typed accessors for organic_results<\/code> and friends, and a raw JsonElement Root<\/code> for the long tail of answer boxes and knowledge graphs.<\/p>\n\n\n\n
4. Newtonsoft to System.Text.Json source generation<\/h2>\n\n\n\n
dropping Newtonsoft isn’t about fashion. with [JsonSerializable]<\/code> source generation you get reflection-free deserialization that’s trim-safe and native-aot-compatible. the library ends up with zero external dependencies. for an sdk, every dependency you don’t take is a diamond-dependency conflict your users don’t have.<\/p>\n\n\n\n
one real-world wrinkle worth showing: SerpApi’s local_results<\/code> is sometimes an array and sometimes an object containing a places<\/code> array, depending on the engine. that’s the kind of thing you only learn by reading actual responses. handle it in the library so your users never see it.<\/p>\n\n\n\n
5. new HttpClient()<\/code> per instance, or bring your own<\/h2>\n\n\n\n
the 2019 client news up its own HttpClient<\/code>. in 2026 the library should accept one. that’s what makes it work with IHttpClientFactory<\/code>, polly resilience pipelines, and unit tests with a fake HttpMessageHandler<\/code>. ship a di package with services.AddSerpApi(...)<\/code> and an ISerpApiClient<\/code> interface, and testing a search feature no longer requires mocking http at all.<\/p>\n\n\n\n
the payoff: a web-grounded agent in 30 lines<\/h2>\n\n\n\n
the reason i care about search apis in .net at all is ai agents. every llm’s knowledge stops at its training cutoff. search grounding fixes that, and everyone does it in python. with a modern client, the c# version is a Semantic Kernel plugin:<\/p>\n\n\n\n
public sealed class SerpApiSearchPlugin(ISerpApiClient client)\n{\n    [KernelFunction(\"search\")]\n    [Description(\"Searches the web and returns the top results.\")]\n    public async Task<string> SearchAsync(string query, CancellationToken ct = default)\n    {\n        using var result = await client.SearchAsync(new SearchRequest { Query = query }, ct);\n        return string.Join(\"\\n\", result.OrganicResults.Select(r => $\"{r.Title} - {r.Link}\\n{r.Snippet}\"));\n    }\n}\n<\/code><\/pre>\n\n\n\n
register it, enable automatic function calling, and the model decides when to search. the full sample, a working console agent, is in the repo.<\/p>\n\n\n\n
takeaways<\/h2>\n\n\n\n
if you maintain an api client, the 2026 checklist is short. async-first with CancellationToken<\/code>. exceptions that preserve their cause. accept an external HttpClient<\/code>. source-generated System.Text.Json<\/code>. typed requests with an untyped escape hatch. an interface for testability. none of it is exotic. it’s just the accumulated lessons of a decade of .net moving on.<\/p>\n\n\n\n
the prs to the official library and the full serpapi-dotnet source are on my github. if you’re at SerpApi and reading this: i’d love to help you tell this story to .net developers properly.<\/em><\/p>\n\n\n\n
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