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AllOf : Only stop when merging schemas with multiple discriminators #667

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Merged
mromaszewicz merged 3 commits into from
Mar 4, 2026
+79 −0
Merged

AllOf : Only stop when merging schemas with multiple discriminators #667

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0d83a0e
AllOf : Only stop when merging schemas with multiple discriminators
Jul 7, 2022
9438657
Merge upstream/main into pr/667, resolving conflict in merge_schemas.go
mromaszewicz Mar 4, 2026
ccd67bd
test(codegen): add tests for discriminator propagation in allOf merges
mromaszewicz Mar 4, 2026
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11 changes: 11 additions & 0 deletions pkg/codegen/merge_schemas.go
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Original file line number Diff line number Diff line change
Expand Up @@ -227,6 +227,17 @@ func mergeOpenapiSchemas(s1, s2 openapi3.Schema, allOf bool) (openapi3.Schema, e
return openapi3.Schema{}, errors.New("merging two schemas with discriminators is not supported")
}

// For allOf merges, propagate a discriminator if only one schema has it.
// Merging two different discriminators is not supported.
if s1.Discriminator != nil && s2.Discriminator != nil {
return openapi3.Schema{}, errors.New("merging two schemas with discriminators is not supported")
}
if s1.Discriminator != nil {
result.Discriminator = s1.Discriminator
} else if s2.Discriminator != nil {
result.Discriminator = s2.Discriminator
}

return result, nil
}

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68 changes: 68 additions & 0 deletions pkg/codegen/merge_schemas_test.go
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Original file line number Diff line number Diff line change
@@ -0,0 +1,68 @@
package codegen

import (
"testing"

"github.com/getkin/kin-openapi/openapi3"
"github.com/stretchr/testify/assert"
"github.com/stretchr/testify/require"
)

func TestMergeOpenapiSchemas_DiscriminatorPropagation(t *testing.T) {
disc := &openapi3.Discriminator{
PropertyName: "type",
}

t.Run("allOf with single discriminator on s1 propagates it", func(t *testing.T) {
s1 := openapi3.Schema{Discriminator: disc}
s2 := openapi3.Schema{}

result, err := mergeOpenapiSchemas(s1, s2, true)
require.NoError(t, err)
assert.Equal(t, disc, result.Discriminator)
})

t.Run("allOf with single discriminator on s2 propagates it", func(t *testing.T) {
s1 := openapi3.Schema{}
s2 := openapi3.Schema{Discriminator: disc}

result, err := mergeOpenapiSchemas(s1, s2, true)
require.NoError(t, err)
assert.Equal(t, disc, result.Discriminator)
})

t.Run("allOf with discriminators on both schemas errors", func(t *testing.T) {
disc2 := &openapi3.Discriminator{PropertyName: "kind"}
s1 := openapi3.Schema{Discriminator: disc}
s2 := openapi3.Schema{Discriminator: disc2}

_, err := mergeOpenapiSchemas(s1, s2, true)
require.Error(t, err)
assert.Contains(t, err.Error(), "discriminators")
})

t.Run("allOf with no discriminators succeeds with nil discriminator", func(t *testing.T) {
s1 := openapi3.Schema{}
s2 := openapi3.Schema{}

result, err := mergeOpenapiSchemas(s1, s2, true)
require.NoError(t, err)
assert.Nil(t, result.Discriminator)
})

t.Run("non-allOf with discriminator on s1 errors", func(t *testing.T) {
s1 := openapi3.Schema{Discriminator: disc}
s2 := openapi3.Schema{}

_, err := mergeOpenapiSchemas(s1, s2, false)
require.Error(t, err)
})

t.Run("non-allOf with discriminator on s2 errors", func(t *testing.T) {
s1 := openapi3.Schema{}
s2 := openapi3.Schema{Discriminator: disc}

_, err := mergeOpenapiSchemas(s1, s2, false)
require.Error(t, err)
})
}