Choosing between 2 middleware in express

Question

Hello i am creating a validation middleware but the problem is i have 2 types to the same endpoint so i created two schema for each.

All i want to do is when type is somthing pass through middleware_a esle return middleware_b

here is my idea but its not working

const middlewareStrategy = (req,res,next) => {
if(req.params.type === "Something"){
   return custom_middleware(schemas.A_body);
}
return custom_middleware(schemas.B_body);};

A_Body here is just validation schema.

Answer 1

It's a bit hard to tell eactly what you're trying to do because you don't show the actual middleware code, but you can dynamically select a middleware a couple of different ways.

Dynamically call the desired processing function

const middlewareStrategy = (req,res,next) => {
    const schema = req.params.type === "Something" ? schemas.A_body : schemas.B_body;
    bodyStrategy(schema, req, res, next);
};

In this middleware, you're dynamically calling a bodyStrategy function that takes the scheme and res, res, next so it can act as middleware, but will know the schema.

Create a middleware that sets the schema on the req object

const middlewareStrategy = (req,res,next) => {
    req.schema = req.params.type === "Something" ? schemas.A_body : schemas.B_body;
    next();
};

Then, use this like:

app.use(middlewareStrategy);   // this sets req.schema to be used by later middleware

Then, you can use another middleware that expects to find the req.schema property to do its job:

app.use(customMiddleware);   // this middleware uses req.schema

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If this isn't exactly what you were looking for, then please include the code of your actual middleware so we can see what we're really aiming for.