Invalid constraints for non-nullable array

When array elements are not nullable, the array validation constraints are applied not to array, but each element
I've modified an existing zod testcase which now fails to visualize this problem:

  it('list field non-null', async () => {
    const schema = buildSchema(/* GraphQL */ `
      input UserCreateInput {
        profile: [String!]! @constraint(minLength: 1, maxLength: 5000)
      }

      directive @constraint(minLength: Int!, maxLength: Int!) on INPUT_FIELD_DEFINITION
    `);
    const result = await plugin(
        schema,
        [],
        {
          schema: 'zod',
          directives: {
            constraint: {
              minLength: ['min', '$1', 'Please input more than $1'],
              maxLength: ['max', '$1', 'Please input less than $1'],
            },
          },
        },
        {}
    );
    const wantContains = [
      'export function UserCreateInputSchema(): z.ZodObject<Properties<UserCreateInput>>',
      'profile: z.array(z.string()).min(1, "Please input more than 1").max(5000, "Please input less than 5000")',
    ];
    for (const wantContain of wantContains) {
      expect(result.content).toContain(wantContain);
    }
  });

@rwysocki-equinix

@rwysocki-equinix Could you send me PR for this fix?

Bumping this, is there any workaround? Or a way to enforce a min length on the zod array ?

Bumping this again.

There is actually no scenario that produces a near-desired outcome.

[String!]! @constraint(min: 5) produces z.array(z.string().min(5))

[String]! @constraint(min: 5) produces z.array(z.string().nullable())

[String!] @constraint(min: 5) produces z.array(z.string().min(1).max(5)).min(1).max(5).nullish()

[String] @constraint(min: 5) produces z.array(z.string().nullable()).min(1).max(5).nullish()

The last one might be the closest but making the array entries nullable isn't great when you generate a client-side schema.

Could someone please provide the schema definition and the desired output?

@Code-Hex

@Code-Hex
Thank you for providing such an excellent library — it's been incredibly helpful in my projects.

I've encountered the same issue and created a minimal reproducible example to demonstrate the problem. I hope this will help you investigate it further.

Repro code repository: https://github.com/hiro1989/repro-graphql-codegen-typescript-validation-schema-array-constraints
Relevant code:
- GraphQL schema: src/graphql/schema.graphql
- Generated code: src/graphql/generated/zod.ts

Versions

All are the current latest version at 2025-10-21

@graphql-codegen/cli: 6.0.0
@graphql-codegen/typescript: 5.0.2
graphql-codegen-typescript-validation-schema: 0.18.1
typescript: 5.9.3
zod: 4.1.1

Summary of Actual vs. Expected Behavior

In short, Array-level @constraint(minItems, maxItems) is incorrectly applied to element schemas instead of the array schema in generated zod code.

Case 1. `[String!]! @constraint(minItems: , maxItems: )`

GraphQL schema:

nicknames: [String!]! @constraint(minItems: 20, maxItems: 21)

Generated code:

// Actual
nicknames: z.array(z.string().min(20).max(21)),

// Expected
nicknames: z.array(z.string()).min(20).max(21),

Case 2. `[String!] @constraint(minItems: , maxItems: )`

GraphQL schema:

nicknamesNullable: [String!] @constraint(minItems: 40, maxItems: 41)

Generated code:

// Actual
nicknamesNullable: z.array(z.string().min(40).max(41)).min(40).max(41).nullish(),

// Expected
nicknamesNullable: z.array(z.string()).min(40).max(41).nullish(),

Case 3. `[String]! @constraint(minItems: , maxItems: )`

GraphQL schema:

nicknamesPartialNullable: [String]! @constraint(minItems: 50, maxItems: 51)

Generated code:

// Actual
nicknamesPartialNullable: z.array(z.string().nullable()),

// Expected
nicknamesPartialNullable: z.array(z.string().nullable()).min(50).max(51),

Case 4. `[SkillInput!]! @constraint(minItems: , maxItems: )`

GraphQL schema:

skills: [SkillInput!]! @constraint(minItems: 60, maxItems: 61)

Generated code:

// Actual
skills: z.array(z.lazy(() => SkillInputSchema().min(60).max(61))),

// Expected
skills: z.array(z.lazy(() => SkillInputSchema())).min(60).max(61),

Case 5. `[SkillInput!] @constraint(minItems: , maxItems: )`

GraphQL schema:

skillsNullable: [SkillInput!] @constraint(minItems: 80, maxItems: 81)

Generated code:

// Actual
skillsNullable: z.array(z.lazy(() => SkillInputSchema().min(80).max(81))).min(80).max(81).nullish(),

// Expected
skillsNullable: z.array(z.lazy(() => SkillInputSchema())).min(80).max(81).nullish(),

Case 6. `[SkillInput]! @constraint(minItems: , maxItems: )`

GraphQL schema:

skillsPartialNullable: [SkillInput]! @constraint(minItems: 90, maxItems: 91)

Generated code:

// Actual
skillsPartialNullable: z.array(z.lazy(() => SkillInputSchema().nullable()))

// Expected
skillsPartialNullable: z.array(z.lazy(() => SkillInputSchema().nullable())).min(90).max(91),

Thank you in advance for your time and support. I really appreciate all the work you're doing on this project!

diff --git a/node_modules/graphql-codegen-typescript-validation-schema/dist/cjs/zodv4/index.js b/node_modules/graphql-codegen-typescript-validation-schema/dist/cjs/zodv4/index.js
index 97519d5..a78c421 100644
--- a/node_modules/graphql-codegen-typescript-validation-schema/dist/cjs/zodv4/index.js
+++ b/node_modules/graphql-codegen-typescript-validation-schema/dist/cjs/zodv4/index.js
@@ -68,7 +68,7 @@ class ZodV4SchemaVisitor extends schema_visitor_js_1.BaseSchemaVisitor {
                         return (new visitor_plugin_common_1.DeclarationBlock({})
                             .export()
                             .asKind('const')
-                            .withName(`${name}Schema: z.ZodObject<Properties<${typeName}>>`)
+                            .withName(`${name}Schema`)
                             .withContent([`z.object({`, shape, '})'].join('\n'))
                             .string + appendArguments);
                     case 'function':
@@ -76,7 +76,7 @@ class ZodV4SchemaVisitor extends schema_visitor_js_1.BaseSchemaVisitor {
                         return (new visitor_plugin_common_1.DeclarationBlock({})
                             .export()
                             .asKind('function')
-                            .withName(`${name}Schema(): z.ZodObject<Properties<${typeName}>>`)
+                            .withName(`${name}Schema()`)
                             .withBlock([(0, visitor_plugin_common_1.indent)(`return z.object({`), shape, (0, visitor_plugin_common_1.indent)('})')].join('\n'))
                             .string + appendArguments);
                 }
@@ -100,7 +100,7 @@ class ZodV4SchemaVisitor extends schema_visitor_js_1.BaseSchemaVisitor {
                         return (new visitor_plugin_common_1.DeclarationBlock({})
                             .export()
                             .asKind('const')
-                            .withName(`${name}Schema: z.ZodObject<Properties<${typeName}>>`)
+                            .withName(`${name}Schema`)
                             .withContent([
                             `z.object({`,
                             (0, visitor_plugin_common_1.indent)(`__typename: z.literal('${node.name.value}').optional(),`, 2),
@@ -113,7 +113,7 @@ class ZodV4SchemaVisitor extends schema_visitor_js_1.BaseSchemaVisitor {
                         return (new visitor_plugin_common_1.DeclarationBlock({})
                             .export()
                             .asKind('function')
-                            .withName(`${name}Schema(): z.ZodObject<Properties<${typeName}>>`)
+                            .withName(`${name}Schema()`)
                             .withBlock([
                             (0, visitor_plugin_common_1.indent)(`return z.object({`),
                             (0, visitor_plugin_common_1.indent)(`__typename: z.literal('${node.name.value}').optional(),`, 2),
@@ -189,7 +189,7 @@ class ZodV4SchemaVisitor extends schema_visitor_js_1.BaseSchemaVisitor {
                 return new visitor_plugin_common_1.DeclarationBlock({})
                     .export()
                     .asKind('const')
-                    .withName(`${name}Schema: z.ZodObject<Properties<${typeName}>>`)
+                    .withName(`${name}Schema`)
                     .withContent(['z.object({', shape, '})'].join('\n'))
                     .string;
             case 'function':
@@ -197,7 +197,7 @@ class ZodV4SchemaVisitor extends schema_visitor_js_1.BaseSchemaVisitor {
                 return new visitor_plugin_common_1.DeclarationBlock({})
                     .export()
                     .asKind('function')
-                    .withName(`${name}Schema(): z.ZodObject<Properties<${typeName}>>`)
+                    .withName(`${name}Schema()`)
                     .withBlock([(0, visitor_plugin_common_1.indent)(`return z.object({`), shape, (0, visitor_plugin_common_1.indent)('})')].join('\n'))
                     .string;
         }
@@ -211,12 +211,13 @@ function generateFieldZodSchema(config, visitor, field, indentCount) {
 function generateFieldTypeZodSchema(config, visitor, field, type, parentType) {
     if ((0, graphql_js_1.isListType)(type)) {
         const gen = generateFieldTypeZodSchema(config, visitor, field, type.type, type);
+        const item = maybeLazy(visitor, type.type, gen);
+        const maybeLazyGen = applyDirectives(config, field, `z.array(${item})`);
+        
         if (!(0, graphql_js_1.isNonNullType)(parentType)) {
-            const arrayGen = `z.array(${maybeLazy(visitor, type.type, gen)})`;
-            const maybeLazyGen = applyDirectives(config, field, arrayGen);
             return `${maybeLazyGen}.nullish()`;
         }
-        return `z.array(${maybeLazy(visitor, type.type, gen)})`;
+        return maybeLazyGen;
     }
     if ((0, graphql_js_1.isNonNullType)(type)) {
         const gen = generateFieldTypeZodSchema(config, visitor, field, type.type, type);
@@ -257,7 +258,25 @@ function generateFieldTypeZodSchema(config, visitor, field, type, parentType) {
 }
 function applyDirectives(config, field, gen) {
     if (config.directives && field.directives) {
-        const formatted = (0, directive_js_1.formatDirectiveConfig)(config.directives);
+        const {constraint, ...rest} = config.directives ?? {};
+        const {minItems, maxItems, ...restConstraint} = constraint ?? {};
+        
+        const newConfig = {
+            ...rest,
+            constraint: restConstraint
+        }
+        
+        if(gen.startsWith('z.array(')) {
+            newConfig.constraint = {};
+            if(minItems) { 
+                newConfig.constraint.minItems = minItems;
+            }
+            if(maxItems) {
+                newConfig.constraint.maxItems = maxItems;
+            }
+        }
+        
+        const formatted = (0, directive_js_1.formatDirectiveConfig)(newConfig);
         return gen + (0, directive_js_1.buildApi)(formatted, field.directives);
     }
     return gen;
diff --git a/node_modules/graphql-codegen-typescript-validation-schema/dist/esm/zodv4/index.js b/node_modules/graphql-codegen-typescript-validation-schema/dist/esm/zodv4/index.js
index 0faadd6..9249af9 100644
--- a/node_modules/graphql-codegen-typescript-validation-schema/dist/esm/zodv4/index.js
+++ b/node_modules/graphql-codegen-typescript-validation-schema/dist/esm/zodv4/index.js
@@ -65,7 +65,7 @@ export class ZodV4SchemaVisitor extends BaseSchemaVisitor {
                         return (new DeclarationBlock({})
                             .export()
                             .asKind('const')
-                            .withName(`${name}Schema: z.ZodObject<Properties<${typeName}>>`)
+                            .withName(`${name}Schema`)
                             .withContent([`z.object({`, shape, '})'].join('\n'))
                             .string + appendArguments);
                     case 'function':
@@ -73,7 +73,7 @@ export class ZodV4SchemaVisitor extends BaseSchemaVisitor {
                         return (new DeclarationBlock({})
                             .export()
                             .asKind('function')
-                            .withName(`${name}Schema(): z.ZodObject<Properties<${typeName}>>`)
+                            .withName(`${name}Schema()`)
                             .withBlock([indent(`return z.object({`), shape, indent('})')].join('\n'))
                             .string + appendArguments);
                 }
@@ -97,7 +97,7 @@ export class ZodV4SchemaVisitor extends BaseSchemaVisitor {
                         return (new DeclarationBlock({})
                             .export()
                             .asKind('const')
-                            .withName(`${name}Schema: z.ZodObject<Properties<${typeName}>>`)
+                            .withName(`${name}Schema`)
                             .withContent([
                             `z.object({`,
                             indent(`__typename: z.literal('${node.name.value}').optional(),`, 2),
@@ -110,7 +110,7 @@ export class ZodV4SchemaVisitor extends BaseSchemaVisitor {
                         return (new DeclarationBlock({})
                             .export()
                             .asKind('function')
-                            .withName(`${name}Schema(): z.ZodObject<Properties<${typeName}>>`)
+                            .withName(`${name}Schema()`)
                             .withBlock([
                             indent(`return z.object({`),
                             indent(`__typename: z.literal('${node.name.value}').optional(),`, 2),
@@ -186,7 +186,7 @@ export class ZodV4SchemaVisitor extends BaseSchemaVisitor {
                 return new DeclarationBlock({})
                     .export()
                     .asKind('const')
-                    .withName(`${name}Schema: z.ZodObject<Properties<${typeName}>>`)
+                    .withName(`${name}Schema`)
                     .withContent(['z.object({', shape, '})'].join('\n'))
                     .string;
             case 'function':
@@ -194,7 +194,7 @@ export class ZodV4SchemaVisitor extends BaseSchemaVisitor {
                 return new DeclarationBlock({})
                     .export()
                     .asKind('function')
-                    .withName(`${name}Schema(): z.ZodObject<Properties<${typeName}>>`)
+                    .withName(`${name}Schema()`)
                     .withBlock([indent(`return z.object({`), shape, indent('})')].join('\n'))
                     .string;
         }

input SkillInput {
  name: String!
  level: Int
}

input TestCase {
  # Case 1: [String!]!
  nicknames: [String!]! @constraint(minItems: 20, maxItems: 21)

  # Case 2: [String!]
  nicknamesNullable: [String!] @constraint(minItems: 40, maxItems: 41)

  # Case 3: [String]!
  nicknamesPartialNullable: [String]! @constraint(minItems: 50, maxItems: 51)

  # Case 4: [SkillInput!]!
  skills: [SkillInput!]! @constraint(minItems: 60, maxItems: 61)

  # Case 5: [SkillInput!]
  skillsNullable: [SkillInput!] @constraint(minItems: 80, maxItems: 81)

  # Case 6: [SkillInput]!
  skillsPartialNullable: [SkillInput]! @constraint(minItems: 90, maxItems: 91)
}

export function SkillInputSchema() {
  return z.object({
    level: z.number().nullish(),
    name: z.string()
  })
}
export function TestCaseSchema() {
  return z.object({
    nicknames: z.array(z.string()).min(20).max(21),
    nicknamesNullable: z.array(z.string()).min(40).max(41).nullish(),
    nicknamesPartialNullable: z.array(z.string().nullable()).min(50).max(51),
    skills: z.array(z.lazy(() => SkillInputSchema())).min(60).max(61),
    skillsNullable: z.array(z.lazy(() => SkillInputSchema())).min(80).max(81).nullish(),
    skillsPartialNullable: z.array(z.lazy(() => SkillInputSchema().nullable())).min(90).max(91)
  })
}

i dont check thoroughly, its not ideal, but have a try with this patch, its zodv4

Fixed in #1423. Zod directives are now applied to non-null array fields instead of being skipped because of the non-null wrapper.

The fix in #1423 covers the Zod generators; valibot still applies list field directives to the items. #1583 ports the same handling to valibot.

Navigation Menu

Repository navigation

Invalid constraints for non-nullable array #489

Versions

Summary of Actual vs. Expected Behavior

Case 1. `[String!]! @constraint(minItems: , maxItems: )`

Case 2. `[String!] @constraint(minItems: , maxItems: )`

Case 3. `[String]! @constraint(minItems: , maxItems: )`

Case 4. `[SkillInput!]! @constraint(minItems: , maxItems: )`

Case 5. `[SkillInput!] @constraint(minItems: , maxItems: )`

Case 6. `[SkillInput]! @constraint(minItems: , maxItems: )`

Metadata

Assignees

Labels

Projects

Milestone

Relationships

Development

Invalid constraints for non-nullable array #489

Description

Activity

Code-Hex commented on Dec 9, 2023

ashar-nadeem-lumi commented on Feb 8, 2024

llwire commented on Nov 15, 2024

Code-Hex commented on Sep 23, 2025

hiro1989 commented on Oct 21, 2025

Versions

Summary of Actual vs. Expected Behavior

Case 1. [String!]! @constraint(minItems: *, maxItems: *)

Case 2. [String!] @constraint(minItems: *, maxItems: *)

Case 3. [String]! @constraint(minItems: *, maxItems: *)

Case 4. [SkillInput!]! @constraint(minItems: *, maxItems: *)

Case 5. [SkillInput!] @constraint(minItems: *, maxItems: *)

Case 6. [SkillInput]! @constraint(minItems: *, maxItems: *)

vinverdy commented on Nov 26, 2025

Code-Hex commented on Apr 25, 2026

Kretiss commented on Sep 23, 2026

Metadata

Metadata

Assignees

Labels

Projects

Milestone

Relationships

Development

Issue actions

Case 1. `[String!]! @constraint(minItems: , maxItems: )`

Case 2. `[String!] @constraint(minItems: , maxItems: )`

Case 3. `[String]! @constraint(minItems: , maxItems: )`

Case 4. `[SkillInput!]! @constraint(minItems: , maxItems: )`

Case 5. `[SkillInput!] @constraint(minItems: , maxItems: )`

Case 6. `[SkillInput]! @constraint(minItems: , maxItems: )`