Using protobuf to link MySQL in unrealeengine plug-in

UnrealEngine Used in plug-ins protobuf link mysql

This chapter completes the requirements ： Complete the project plug-in , Can provide customized protobuf agreement
step ： compile protobuf, New plug-in import protobuf Library and use , The project project calls the open interface of the plug-in

Get ready

First read the following official tutorial
Plug in creation and use best practices - Module and engine architecture
modular
Third party Library
Game module

matters needing attention
UE4 Debugging third-party libraries

The main points of
The module is UE4 The building blocks of . The engine is implemented as a collection of a large number of modules , The game provides its own modules to expand itself .

Module is through C# Declared by the source file , extension .build.cs

UE4 The compiler does not support the use of by default debug Version of the third-party library .（ The default option can be changed ）

The default generated runtime option is /MD, namely Multithreading Dll[/MD]. If the link library appears XXX Mismatches : value “0” Mismatch value “2”, Most of them are runtime version errors

Multithreading [/MT]:0
Multithreaded debugging [/MTd]:1
Multithreading DLL[/MD]:2
Multithreaded debugging DLL[/MDd]:3

A profound

Connect mysql library unreal Connect mysql

compile protobuf

Pit point ：protobuf according to README It compiles lib Static library , Most online compilation tutorials are also /MT edition

reference protobuf compile
use cmake-gui Generate vs engineering , Note the options checked during generation ,runtime=off,test=off, shared_lib=on, Then compile and generate libprotobuf.dll that will do

Writing a plug-in

First write a simple plug-in , Skilled students can directly build the file hierarchy in the file manager , Write a document from scratch , Unskilled opening ue Editor ,Edit->Plugins->New Plugin->Blank Create an empty plug-in , I'm going to call it TestProtobuf. Run after the construction , Run through ok

stay Public New folder under folder Include,Library（ convenience , Build everywhere ok）, There is something missing in it

Add the following two lines to build.cs file . Note that the library is not copied to Binaries Under the folder , Not applicable to package release .

PublicIncludePaths.Add(Path.Combine(ModuleDirectory, "Private", "Include"));
PublicAdditionalLibraries.Add(Path.Combine(ModuleDirectory, "Private", "Library", "libprotobuf.lib"));

PS: The folder location has nothing to do with the actual private and public containment , Only for the sake of specification, private files are placed in Private Under the folder , Put the public in Public Under the folder . You can do it test： stay Public Under the folder , take protobuf Source code google Folders and generated pb.h The files are in the same directory , stay Build.cs Use... In the document PrivateIncludePaths.Add(), At this time, you can also compile

Pit point ： Generated ph.h It's using <>, use PrivateInclude… after , If ph.cc And google Problems with the relative location of folders can cause a lot of trouble

Pit point ： Sometimes external symbolic link errors will be reported after compilation , Characteristic is StartupModule Function error for . Because the export library should be in class Back plus PLUGINNAME_API, Otherwise, the plug-in will not be linked to . Keep in mind that modules compile into libraries

Here's something to do test, Class adds only one function
TestData.proto

syntax = "proto3";

message Account {
    string name = 1;     //  Account name 
    string password = 2;     //  password 
    int32 loginType = 3;     //  Landing type ,0 register  1 land 
}

class TESTPROTOBUF_API FTestProtobufModule : public IModuleInterface
{
    
public:

	/** IModuleInterface implementation */
	virtual void StartupModule() override;
	virtual void ShutdownModule() override;
	void SetAccount(const FString& name, const FString& password, const int32& loginType);
	Account account;
};

void FTestProtobufModule::SetAccount(const FString& name, const FString& password, const int32& loginType)
{
    
	account.set_name(TCHAR_TO_ANSI(*name));
	account.set_password(TCHAR_TO_ANSI((*password)));
	account.set_logintype(loginType);
}

test

At this point, the plug-in is written . Let's start with build.cs Import module inside . Here we use the above small test ox knife mysql Example , Test in the blueprint library

UCLASS()
class TESTPLUGIN_API UMyBlueprintFunctionLibrary : public UBlueprintFunctionLibrary
{
    
	GENERATED_BODY()
public:
	UFUNCTION(BlueprintCallable, Category="MySQL")
	static bool TestMySQL();

	UFUNCTION(BlueprintCallable, Category="MySQL")
	static void TestProtobuf();
};

void UMyBlueprintFunctionLibrary::TestProtobuf()
{
    
	FTestProtobufModule ProtobufModule;
	ProtobufModule.SetAccount("hui", "test", 0);
}

Pit point ： If protobuf Library error , First think about whether there is reference protobuf compile , add to #define PROTOBUF_USE_DLLS