UE4 HTTP Response on BlueprintCallable and Delegates

Development Programming & Scripting
1

Hello everyone. I’m trying to do http request and response on c++ as blueprintcallable. But I couldn’t handle the delegates. I cannot access HTTP Response after binding OnResponseRecieved function. How can I access my HTTP Response on blueprintcallable. I couldn’t succeed on Multicast delegates.If you think Multicast Delegates is the best option for this. Can you help me with that. here is my codes

MyBlueprintFunctionLibrary.h

#pragma once

#include "CoreMinimal.h"
#include "Kismet/BlueprintFunctionLibrary.h"
#include "Runtime/Online/HTTP/Public/Http.h"
#include "Runtime/Core/Public/Delegates/Delegate.h"
#include "MyBlueprintFunctionLibrary.generated.h"

/**
 * 
 */


UCLASS()
class TESTPLUGIN_API UMyBlueprintFunctionLibrary : public UBlueprintFunctionLibrary
{
	GENERATED_BODY()
public:
	FString ApiBaseUrl;
   
	UFUNCTION(BlueprintCallable, Category = "HTTP")
	static void SetBaseURL(FString BaseURL, FString& ApiBaseUrl);

	UFUNCTION(BlueprintCallable, Category = "HTTP")
	static void RequestCall(FString ApiBaseUrl, FString Subroute);

	static void OnResponseReceived(FHttpRequestPtr Request, FHttpResponsePtr Response, bool bWasSuccessful);

};

MyBlueprintFunctionLibrary.cpp

#include "MyBlueprintFunctionLibrary.h"
#include "Runtime/Json/Public/Json.h"
 
void UMyBlueprintFunctionLibrary::SetBaseURL(FString BaseURL, FString& ApiBaseUrl) {
	ApiBaseUrl = BaseURL;
	UE_LOG(LogTemp, Warning, TEXT("BaseURL is worked"));
}

void UMyBlueprintFunctionLibrary::RequestCall(FString ApiBaseUrl, FString Subroute) {
	FHttpModule* Http = &FHttpModule::Get();
	TSharedRef<IHttpRequest> Request = Http->CreateRequest();
	UE_LOG(LogTemp, Warning, TEXT("Request is worked"));
	FScriptDelegate Delegate;
	Request->OnProcessRequestComplete().BindStatic(UMyBlueprintFunctionLibrary::OnResponseReceived);
	Request->SetURL(ApiBaseUrl + Subroute);
	Request->SetHeader(TEXT("User-Agent"), TEXT("X-UnrealEngine-Agent"));
	Request->SetHeader(TEXT("Content-Type"), TEXT("application/json"));
	Request->SetHeader(TEXT("Accepts"), TEXT("application/json"));
	Request->ProcessRequest();
}

/*Assigned function on successfull http call*/
void UMyBlueprintFunctionLibrary::OnResponseReceived(FHttpRequestPtr Request, FHttpResponsePtr Response, bool bWasSuccessful)
{
	UE_LOG(LogTemp, Warning, TEXT("OnResponseReceived function is ready!!"));
	//Create a pointer to hold the json serialized data
	TSharedPtr<FJsonObject> JsonObject;

	//Create a reader pointer to read the json data
	TSharedRef<TJsonReader<>> Reader = TJsonReaderFactory<>::Create(Response->GetContentAsString());
	//Deserialize the json data given Reader and the actual object to deserialize
	if (FJsonSerializer::Deserialize(Reader, JsonObject))
	{
		//Get the value of the json object by field name
		int32 recievedInt = JsonObject->GetIntegerField("userId");

		//Output it to the engine
		UE_LOG(LogTemp, Warning, TEXT("Response is coming xP"));
		UE_LOG(LogTemp, Warning, TEXT("Id is: %d"), recievedInt);
	}
}
2

I would love to do something very similar, so if anyone could help, that would be great.

3

This is an old post now, but for anyone who comes across it looking for something similar; the easiest way to deal with it is to use

4

This is an old post now, but for anyone who comes across it looking for something similar; the easiest way to deal with it is to use BindLambda instead of BindStatic. Then you can pass the callback directly to the lambda function.

Here is the simplest example I can think of, which takes a callback function in blueprints and calls it when the request goes through. You can of course add JSON handling and all that to the lambda function.

MyBlueprintFunctionLibrary.h

#pragma once

#include "CoreMinimal.h"
#include "Kismet/BlueprintFunctionLibrary.h"
#include "HttpFunctionLibrary.generated.h"


DECLARE_DYNAMIC_DELEGATE_ThreeParams(FHttpRequestResponse, FString, ResponseString, int, HttpStatus, bool, Success);

/**
 * 
 */
UCLASS()
class HTTPTESTING_API UMyBlueprintFunctionLibrary : public UBlueprintFunctionLibrary
{
	GENERATED_BODY()

	UFUNCTION(BlueprintCallable)
	static void GetRequest(FString URL, FHttpRequestResponse Callback);
	
};

MyBlueprintFunctionLibrary.cpp

#include "MyBlueprintFunctionLibrary.h"

#include "HttpModule.h"
#include "Interfaces/IHttpResponse.h"

void UMyBlueprintFunctionLibrary::GetRequest(FString URL, FHttpRequestResponse Callback)
{
	auto Http = &FHttpModule::Get();

	FHttpRequestPtr Request = Http->CreateRequest();
	Request->SetURL(URL);
	Request->SetVerb("GET");
	Request->OnProcessRequestComplete().BindLambda([Callback](FHttpRequestPtr Request, FHttpResponsePtr Response, bool bWasSuccessful)
	{
		Callback.ExecuteIfBound(Response->GetContentAsString(), Response->GetResponseCode(), bWasSuccessful);
	});
	Request->ProcessRequest();
}

The other way of doing it would be to use UObjects instead, and bind to UObject functions. There are examples of how to do it here: GitHub - nsjames/UE4_Tutorial_Http: Proper usage of HTTP within UE4

5

About HTTP response on BlueprintCallable and Delegates, maybe get some inspiration from this plugin: