how to write a middleware?

A middleware is a function, the function signature is void Func(vogro::Context & ctx), ctx.Next() calls the next handler/middleware in the handler/middleware array.

The following is an simple example middleware:

void TestMiddleWare1(vogro::Context& ctx) {
    std::cout << "hello from middleware1" << std::endl;
    ctx.Next();
}

If you need to pass information between middlewares，you can use ctx.setValue(),ctx.getValue(). the following is an example:

void TestMiddleWare1(vogro::Context& ctx) {
    std::cout << "hello from middleware1" << std::endl;
    ctx.setValue("key","value from middleware1");
    ctx.Next();
}

void TestMiddleWare2(vogro::Context& ctx) {
    std::cout << "hello from middleware2" << std::endl;
    auto val = ctx.getValue("key");  // val == "value from middleware1"
    ctx.Next();
}