I am struggling with mongoose.

I have a filter that I want to use to search through my model, which is:

const recipeSchema = new Schema(
    {
        name: { type: String, required: [true, "Recipe must have a name"] },
        category: {
            type: ObjectId,
            ref: "Category",
            required: [true, "Recipe must belong to a category"],
        },
        difficulty: { type: String, enum: ["easy", "medium", "hard"] },
    }
);

Category can be either all for all categories, or a specific id.

Difficulty can be either [] for all difficulties, or a specific difficulty defined above.

Right now I have this, which semi works:

if (category !== "all") {
        recipes = await Recipe.find({ ...searchTerm })
            .where("category")
            .equals(category)
            .where("difficulty")
            .equals(difficulty)
            .exec();
    } else {
        recipes = await Recipe.find({ ...searchTerm });
    }

I know why the above code doesn’t work as I want it, I just don’t know how to get it to do what I want.

So the above works only if a category is selected (can’t be all obviously) and if there is exactly one item in the array, if the array is empty it doesn’t work.

I would like it to search irrespective of category if all is selected for category, and irrespective of difficulty is the difficulty is [], but also be able to filter based on more than one difficulty.

Help please?