C#•2mo ago

✅ Getting method parameters with reflection on library code

Hi everyone, so I'm making a wrapper/library for a rest api, and to trying to simplify the code i ended up using reflection to get a method's parameters, something like this:

async Task<T> GetAsync(string service, ParameterInfo[] parameters, params object[] values)
{
  // make dictionary from parameters and values
  Dictionary<string, string> args = ...
  
  // make the http request and return the response
  HttpRequestMessage request = new(HttpMethod.Get, $"{service}?{string.Join('&', args.Select(x => $"{x.Key}={x.Value}"))}");
  ...
}

// here's where i'm using reflection
async Task<Model1> Example1(int arg1, int arg2, string arg3) =>
  await GetAsync<Model1>("service1", MethodBase.GetCurrentMethod().GetParameters(), arg1, arg2, arg3);

async Task<Model2> Example2(double arg1, char arg2) =>
  await GetAsync<Model2>("service2", MethodBase.GetCurrentMethod().GetParameters(), arg1, arg2);

async Task<T> GetAsync(string service, ParameterInfo[] parameters, params object[] values)
{
  // make dictionary from parameters and values
  Dictionary<string, string> args = ...
  
  // make the http request and return the response
  HttpRequestMessage request = new(HttpMethod.Get, $"{service}?{string.Join('&', args.Select(x => $"{x.Key}={x.Value}"))}");
  ...
}

// here's where i'm using reflection
async Task<Model1> Example1(int arg1, int arg2, string arg3) =>
  await GetAsync<Model1>("service1", MethodBase.GetCurrentMethod().GetParameters(), arg1, arg2, arg3);

async Task<Model2> Example2(double arg1, char arg2) =>
  await GetAsync<Model2>("service2", MethodBase.GetCurrentMethod().GetParameters(), arg1, arg2);

Now i've heard that reflection is pretty inefficient, so considering that this is library code that other people might end up using, is this a bad idea? should i try another, maybe more efficient, method? btw i have no idea what tags i should add to this

33 Replies

sibber•2mo ago

why not have the user pass in a collection of arguments?

LeroicoOP•2mo ago

you mean asking the user for the arguments?

sibber•2mo ago

or create a strongly typed object with all the possible arguments for each endpoint depends on the api if thats a good idea or not yeah what youre doing now seems too convoluted for no apparent benefit to me

LeroicoOP•2mo ago

its wrapping a weather api, so the idea is that there are methods like GetPastWeather() or GetCurrentWeather() and the user passes (for example) the coordinates of the location, so i'm not sure how i would implement that

sibber•2mo ago

method overloads one for coordinates, one for location name, etc

LeroicoOP•2mo ago

ok i get you that was my initial idea

Sehra•2mo ago

or simply GetAsync<T>(string service, IDictionary<string, object> values), or string,string if you want to format the values in Example1/Example2

LeroicoOP•2mo ago

that's what i was doing, but in every example method i needed to create a new dictionary, while hardcoding the names of the parameters there's not really a problem with that

sibber•2mo ago

all you need is IEnumerable<KeyValuePair<TKey,TValue>>

LeroicoOP•2mo ago

but i was trying to repeat less code

sibber•2mo ago

you can create an overload that takes a span to avoid allocs if youre on .net 9 you can use params with that

LeroicoOP•2mo ago

i'm on .net 8

sibber•2mo ago

repeating less isnt always better

Sehra•2mo ago

i'd also change the query string creation to escape the keys/values properly

sibber•2mo ago

people follow DRY too religiously

LeroicoOP•2mo ago

how would i do that?

sibber•2mo ago

and in a lot of cases end up with way less readable or overengineered code url encode

LeroicoOP•2mo ago

ok i'll be doing that next

sibber•2mo ago

although iirc HttpClient should handle that but dont quote me

LeroicoOP•2mo ago

i don't know if this image is readable but this is the code i'm using to send the request

LeroicoOP•2mo ago

just to clear anything up so in this case getparameters() is kind of overkill?

Sehra•2mo ago

think it should be $"{Uri.EscapeDataString(x.Key)}={Uri.EscapeDataString(x.Value)}"

sibber•2mo ago

use GetFromJsonAsync but method overloads seem like the best option here definitely thats not what reflection is intended for

LeroicoOP•2mo ago

ok thanks for the help i'll use that thanks do i need to escape the key if i'm going to be hardcoding them?

Sehra•2mo ago

no, then you know what they are

sibber•2mo ago

hardcode the url encoded version

LeroicoOP•2mo ago

alright thanks again for the help

sibber•2mo ago

LeroicoOP•2mo ago

btw if i configured my httpclient with a baseurl that will still work with GetFromJsonAsync right just making sure

sibber•2mo ago

yeah

LeroicoOP•2mo ago

nice do i delete the post now?

sibber•2mo ago

$close

MODiX•2mo ago

If you have no further questions, please use /close to mark the forum thread as answered

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✅ Getting method parameters with reflection on library code

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