Fix issue #1611

[john-schmitz]

closes #1611

I quickly drafted a working solution so we could iterate and discuss its design.

I also added the same proposed behavior to strings as well, since both strings and arrays share the .length function.

Looking further into the codebase, I think it would be ideal to create a new check (something like "exact_legth") and a ZodIssueCode so we can share the same locale behavior between Arrays and Strings.

Whats your take? How should I integrate those changes into Zod's current codebase?

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[maxArturo]

Whats your take? How should I integrate those changes into Zod's current codebase?

IMO this seems very sensible - especially since there's no API changes and seems in line with the current way of organizing error messages. Just my $0.02 USD. Thanks for the pr @john-schmitz !

[john-schmitz]

Glad to help. The impact Zod had on my workflow is immense.
Always good to give back.

[santosmarco-caribou]

Hmm... I'm not sure if I like this solution. (but correct me if I'm wrong)

You are setting the default message directly on the method, promoting it to the highest priority level when generating the final message.

Say, for example, I've decided to define my error map on the .parse() call:

const myArraySchema = z.array(z.string()).length(2).parse(["foo"], {
  errorMap: (issue) => {
    if (issue.code === "too_small") {
      return { message: "Hey yo, the array must have a length of 2." };
    }
    return { message: "Nope" };
  },
});

Since I'm not setting the "Hey yo, the array must have a length of 2." message in the .length(2) call, it will be overwritten by your default message because messages set directly on the check ('length') call have the highest priority (I'm not setting it there, but you are).

Default messages should always have the lowest priority.

Can you please add a test of the above code and see the result?

[colinhacks]

As @santosmarco-caribou says, the original approach does break Zod's error message hierarchy. I pushed a commit that uses a different approach, adding an optional exact flag (alongside inclusive) that we can use to customize the default error message here. Achieves the goal in a backwards compatible way.