feat (form-core): Merging Form-level server errors with Field-level errors #1432

theVedanta · 2025-04-20T19:04:31Z

Instead of the previous serverValidate function just returning a string, we now return an object:

const serverValidate = createServerValidate({
  ...formOpts,
  onServerValidate: ({ value }) => {
    if (value.age < 12)
      return { age: 'Server validation: You must be at least 12 to sign up' }
  },
})

This then maps to the field-level errors with the setMeta options.

The only reason this is called a preliminary approach is because we are setting the onServer key of the errorMap differently.

Previously, the error map for the form looked like so:

{
  onServer: "You need to be 12 years or older to sign up"
}

Now however, the onServer map is slightly different:

{
  onServer: { age: "You need to be 12 years or older to sign up" }
}

This causes some degree of inconsistency, which is why I would love some feedback on whether we can use some other property (or maybe create our own!) to manage the errors between fields and forms. This would not be a comprehensive property but just a map to sync them back and forth.

NextJS support has been pushed. Remix and Start coming soon.
Support for Array field types will also be done shortly.

Would love your feedback and comments on this approach before I proceed!

Solves the following issue: #1260

nx-cloud · 2025-04-20T19:04:50Z

View your CI Pipeline Execution ↗ for commit d06c1ff

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☁️ Nx Cloud last updated this comment at 2025-10-31 21:16:04 UTC

pkg-pr-new · 2025-04-20T19:05:51Z

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commit: d06c1ff

codecov · 2025-04-20T19:07:41Z

Codecov Report

❌ Patch coverage is 7.14286% with 39 lines in your changes missing coverage. Please review.
✅ Project coverage is 89.10%. Comparing base (6892ed0) to head (d06c1ff).
⚠️ Report is 70 commits behind head on main.

Files with missing lines	Patch %	Lines
packages/form-core/src/FormApi.ts	18.75%	10 Missing and 3 partials ⚠️
...ages/react-form/src/nextjs/createServerValidate.ts	0.00%	10 Missing and 3 partials ⚠️
...kages/react-form/src/remix/createServerValidate.ts	0.00%	10 Missing and 3 partials ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1432      +/-   ##
==========================================
- Coverage   90.35%   89.10%   -1.25%     
==========================================
  Files          38       38              
  Lines        1752     1836      +84     
  Branches      444      471      +27     
==========================================
+ Hits         1583     1636      +53     
- Misses        149      173      +24     
- Partials       20       27       +7

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…-validation-merged-with-field-errors

…-errors

…github.com/theVedanta/form into server-validation-merged-with-field-errors

vincehi · 2025-09-16T09:40:17Z

Hello, do you need a hand to move this branch forward? I would love to see it happen :)

theVedanta · 2025-09-17T23:05:31Z

Hello, do you need a hand to move this branch forward? I would love to see it happen :)

Yeah sure dude, go for it!

theVedanta · 2025-10-19T18:33:12Z

Not sure if this feature is still requested or whether it has been fixed. Don't wanna tag maintainers but this has been dormant for a while, I'd like some insight on how to proceed! @LeCarbonator @harry-whorlow

LeCarbonator

Sorry for the long delay! I'm not too confident in my SSR knowledge, so I'll make sure to give this a try myself. I'll also go through some issues and the reproductions to confirm things.

Hopefully, this initial review should help with some refactoring. It's looking promising!

Since this has been stale for way too long, this will be my focus for now. Feel free to tag me if there's more info you need or a second review. I can also help out with the PR if you'd like.

LeCarbonator · 2025-10-24T09:09:04Z

packages/react-form/src/nextjs/createServerValidate.ts

      validationSource: 'form',
    })) as UnwrapFormAsyncValidateOrFn<TOnServer> | undefined

+    console.log('ON SERVER ERROR', onServerError)


Forgotten console.log

LeCarbonator · 2025-10-24T09:13:08Z

packages/react-form/src/nextjs/createServerValidate.ts

+    const errorsArray = onServerErrorVal
+      ? Array.isArray(onServerErrorVal)
+        ? onServerErrorVal.map((err) =>
+            typeof err === 'object' ? Object.values(err)[0] : err,
+          )
+        : [
+            typeof onServerErrorVal === 'object'
+              ? Object.values(onServerErrorVal)[0]
+              : onServerErrorVal,
+          ]
+      : []


This double ternary is a bit hard to follow. Please refactor to if statements instead.

LeCarbonator · 2025-10-24T09:14:18Z

packages/react-form/src/nextjs/createServerValidate.ts

+    const errorsArray = onServerErrorVal
+      ? Array.isArray(onServerErrorVal)
+        ? onServerErrorVal.map((err) =>
+            typeof err === 'object' ? Object.values(err)[0] : err,


I'll need to look into this one. Objects don't inherently have an order, so I'm not sure how consistent taking the first element would be. Perhaps we do this in other places?

The object format you're referring to is the server error fields coming in, right?

There is actually an order of sorts nowadays: https://2ality.com/2015/10/property-traversal-order-es6.html

Integer indices (array-like indices) come first, in ascending numeric order

String keys (non-integer strings) come next, in creation order

Symbol keys come last, in creation

I'll need to look into this one. Objects don't inherently have an order, so I'm not sure how consistent taking the first element would be. Perhaps we do this in other places?

The object format you're referring to is the server error fields coming in, right?

I've checked and recalled why the Object.values()[0] was in there. It was a part of the "Preliminary approach" of the draft PR, which is no longer relevant. Please check the latest commit. This now contains a simple parse for objects / strings.

The server can now return 2 kinds of things:

// Type 1 (an object) return { fields: { age: "Field Error: Should be 12 to sign up" }, form: "" // Can be blank or omitted, but populates the form error if filled } // Type 2 return "Form Error: Should be 12 to sign up"

Let me know if you think anything needs further fixing.

LeCarbonator · 2025-10-24T09:23:23Z

The merge conflicts appear to be in some of the important diffs, so I'll leave that up to you. I'll see if convenient unit tests could be made for these as we don't want to regress on this.

theVedanta · 2025-10-28T03:13:13Z

Sorry for the long delay! I'm not too confident in my SSR knowledge, so I'll make sure to give this a try myself. I'll also go through some issues and the reproductions to confirm things.

Hopefully, this initial review should help with some refactoring. It's looking promising!

Since this has been stale for way too long, this will be my focus for now. Feel free to tag me if there's more info you need or a second review. I can also help out with the PR if you'd like.

Your help with the PR would be awesome! I'm pretty new to learning about the tanstack ecosystem.
I'll try to make another commit with the fixes.

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theVedanta · 2025-11-19T19:04:28Z

@LeCarbonator just following up on this :)

crutchcorn · 2025-12-01T09:44:18Z

@theVedanta I'm super sorry about this, but I've realized that our SSR story is DEEPLY broken (my fault, not related to this specifically).

As such, I'm prototyping new ideas here:

#1890

While I don't want the general public to worry about any potential breaking changes yet (we'll have extensive migration guides and such), I'd love you thoughts on the approach I took there to fix things.

LMK!

Thanks a billion for your amazing help. Closing this PR to move discussions there

theVedanta · 2025-12-01T18:54:17Z

@theVedanta I'm super sorry about this, but I've realized that our SSR story is DEEPLY broken (my fault, not related to this specifically).

As such, I'm prototyping new ideas here:

#1890

While I don't want the general public to worry about any potential breaking changes yet (we'll have extensive migration guides and such), I'd love you thoughts on the approach I took there to fix things.

LMK!

Thanks a billion for your amazing help. Closing this PR to move discussions there

haha no worries man. and thanks so much for closing this. I ended up discussing this PR with Luca but totally forgot to close it! I would love to check out the awesome work you're doing to improve the SSR :)

preliminary approach for merging server errors

aecdb83

theVedanta marked this pull request as draft April 20, 2025 19:08

theVedanta changed the title ~~Merging Form-level server errors with Field-level errors~~ feat (form-core): Merging Form-level server errors with Field-level errors Apr 22, 2025

theVedanta added 6 commits May 7, 2025 12:42

server map checked for empty value

a9d48c9

Merge branch 'main' of https://github.com/theVedanta/form into server…

fde9554

…-validation-merged-with-field-errors

Merge branch 'main' of https://github.com/theVedanta/form into server…

bea32b5

…-validation-merged-with-field-errors

Merge branch 'TanStack:main' into server-validation-merged-with-field…

bc561fc

…-errors

Merge branch 'server-validation-merged-with-field-errors' of https://…

9d70231

…github.com/theVedanta/form into server-validation-merged-with-field-errors

using the global error type

9413ca6

theVedanta marked this pull request as ready for review July 7, 2025 07:29

LeCarbonator requested changes Oct 24, 2025

View reviewed changes

removed console.log + changed to if statements

7c22179

theVedanta added 4 commits October 27, 2025 20:30

removed console.log + changed to if statements

3c82c98

merge

e86715e

added simplification of object.values()[0] -> simple fields object usage

c922835

remix support

d06c1ff

crutchcorn closed this Dec 1, 2025

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feat (form-core): Merging Form-level server errors with Field-level errors #1432

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