- Add Response Headers to IApiResult

Author: NinjaRocks

README.md

@@ -80,15 +80,19 @@ The purpose of a api class is to execute the web api with api engine to fetch th
 
 As mentioned previously, You can configure an api in `Parent` or `Child` (nested) mode in a hierarchical graph.
 
-To define a `parent` or `nested` api you need to implement from `WebApi<TResult>` class where `TResult` is the result that will be returned from executing the api.  It is an implementation of `IApiResult` type.
-Upon creating the api class. You need to provide below `GetUrl()` implementation.
-* Implement the `GetUrl(IRequestContext context, IApiResult parentApiResult)` method to return the constructed endpoint based on given parameters of the method.
-* For Parent Api, Only `IRequestContext` context parameter is passed to GetUrl() method to resolve the Url endpoint. 
-* For Nested Api, api result parameter (ie. `IApiResult` parentApiResult) from the parent api is additionally passed in to GetUrl() method along with IRequestContext context parameter.
-
-Please Note: `IApiResult` parentApiResult parameter is null for apis configured in parent mode.
+To create `Web Api` defined as `parent` or `nested` api, you need to implement from `WebApi<TResult>` class,
+where `TResult` is `IApiResult` interface (or `ApiResult` base class) implementation and is the result that will be returned from executing the api.
 
-`Important:` The api `endpoint` needs to be resolved before executing the api with `ApiEngine`.
+Upon creating the web api class, you need to provide `GetUrl()` method implementation.
+* Implement the `GetUrl(IRequestContext context, IApiResult parentApiResult)` method to return the constructed endpoint based on given parameters of the method.
+* For `Parent Api`, only `IRequestContext` context parameter is passed to GetUrl() method to resolve the Url endpoint. 
+* For `Nested Api`, api result parameter (ie. `IApiResult` parentApiResult) from the parent api is additionally passed in to GetUrl() method along with IRequestContext context parameter.
+* Optionally, override `GetHeaders()` method to provide any list of `request headers` for the api.
+* `IApiResult` implementation exposes `Headers` property for any `response headers` received as part of the api response.
+
+`Important:`
+- The api `endpoint` needs to be resolved before executing the api with `ApiEngine`.
+- `IApiResult` parentApiResult parameter is null for apis configured in parent mode.
 
 Examples.
 

src/ApiAggregator/ApiResult.cs

@@ -0,0 +1,12 @@
+namespace ApiAggregator.Net
+{
+    public abstract class ApiResult : IApiResult
+    {
+        public ApiResult()
+        {
+            Headers = [];
+        }
+
+        public List<KeyValuePair<string, string>> Headers { get; set; }
+    }
+}

src/ApiAggregator/CollectionResult.cs

@@ -4,6 +4,9 @@ public class CollectionResult<T> : List<T>, IApiResult
     {
         public CollectionResult(IEnumerable<T> list) : base(list)
         {
+            Headers = [];
         }
+
+        public List<KeyValuePair<string, string>> Headers { get; set; }
     }
 }

src/ApiAggregator/IApiResult.cs

@@ -2,5 +2,6 @@ namespace ApiAggregator.Net
 {
     public interface IApiResult
     {
+        List<KeyValuePair<string, string>> Headers { get; }
     }
 }

src/ApiAggregator/WebApi.cs

@@ -128,15 +128,22 @@ public virtual async Task<IApiResult> Run(IHttpClientFactory httpClientFactory,
                             {
                                 var resultType = typeof(CollectionResult<>);
                                 var collectionType = resultType.MakeGenericType(typeArgs);
-                                var collectionResult = Activator.CreateInstance(collectionType, arrObject);
-                                return (TResult)collectionResult;
+                                var collectionResult = (TResult)Activator.CreateInstance(collectionType, arrObject);
+
+                                SetResponseHeaders(result, collectionResult);
+
+                                return collectionResult;
                             }
                         }
                         else
                         {
                             var obj = JsonSerializer.Deserialize(raw, typeof(TResult));
                             if (obj != null)
-                                return (TResult)obj;
+                            {
+                                var resObj = (TResult)obj;
+                                SetResponseHeaders(result, resObj);
+                                return resObj;
+                            }
                         }
                     }
                     catch (TaskCanceledException ex)
@@ -157,6 +164,14 @@ public virtual async Task<IApiResult> Run(IHttpClientFactory httpClientFactory,
             }
 
             return null;
+
+            static void SetResponseHeaders(HttpResponseMessage response, TResult? result)
+            {
+                if (response.Headers != null && result != null)
+                    foreach (var header in response.Headers)
+                        result?.Headers?.Add(new KeyValuePair<string, string>(header.Key,
+                            header.Value != null && header.Value.Any() ? header.Value.ElementAt(0) : null));
+            }
         }
     }
 }

tests/ApiAggregator.Tests/ApiAggregate/ApiResults/CommunicationResult.cs

@@ -3,7 +3,7 @@
 namespace ApiAggregator.Tests.ApiAggregate.ApiResults
 {
     [CacheResult]
-    public class CommunicationResult : IApiResult
+    public class CommunicationResult : ApiResult
     {
         public int Id { get; set; }
         public string Telephone { get; set; }

tests/ApiAggregator.Tests/ApiAggregate/ApiResults/CustomerResult.cs

@@ -2,7 +2,7 @@
 
 namespace ApiAggregator.Tests.ApiAggregate.ApiResults
 {
-    public class CustomerResult : IApiResult
+    public class CustomerResult : ApiResult
     {
         public int Id { get; set; }
         public string Code { get; set; }

tests/ApiAggregator.Tests/ApiAggregate/ApiResults/OrderItemResult.cs

@@ -2,7 +2,7 @@
 
 namespace ApiAggregator.Tests.ApiAggregate.ApiResults
 {
-    public class OrderItemResult : IApiResult
+    public class OrderItemResult : ApiResult
     {
         public int OrderId { get; set; }
         public int ItemId { get; set; }

tests/ApiAggregator.Tests/ApiAggregate/ApiResults/OrderResult.cs

@@ -2,7 +2,7 @@
 
 namespace ApiAggregator.Tests.ApiAggregate.ApiResults
 {
-    public class OrderResult : IApiResult
+    public class OrderResult : ApiResult
     {
         public int OrderId { get; set; }
         public string OrderNo { get; set; }