为什么会抛出“循环依赖”？

Question

I don't get why yup throws cyclic dependency at all. When referring to other fields, we are referring to value, not the schema itself aren't we ?

More than just something that I don't get, I found myself blocked while requiring a conditional schema validation.

const yup = require("yup");

it("should pass", async () => {
  const schema = yup.object({
    name: yup.string().when("name", {
      is: name => name !== "dummy",
      otherwise: yup.string().email("Email or dummy.")
    })
  });

  const obj = {
    name: "dummy"
  };

  await expect(schema.isValid(obj)).resolves.toBe(true);
});

codesandbox

Also, is there nothing like or or either into the DSL ?

The question is really about, why does yup throw cyclic dependency, not about this specific case.

Answer 1

Getting around the problem with:

const schema = yup.object({
    name: yup.string().when([], (v, { originalValue }) => 
      originalValue.name === "dummy" ? yup.string() : yup.email("Email or dummy")
    )
);

But it doesn't look like the natural way, + I still don't get how a schema can generate cyclic dependency.