fix: allow metadata-only collection updates

typesense/api/generator/generator.yml

@@ -380,6 +380,7 @@ components:
         - fields
       type: object
     CollectionUpdateSchema:
+      minProperties: 1
       properties:
         fields:
           description: A list of fields for querying, filtering and faceting
@@ -396,6 +397,7 @@ components:
           items:
             $ref: '#/components/schemas/Field'
           type: array
+          x-go-type-skip-optional-pointer: true
         metadata:
           description: |
             Optional details about the collection, e.g., when it was created, who created it etc.
@@ -406,8 +408,6 @@ components:
             example: synonym_set_1
             type: string
           type: array
-      required:
-        - fields
       type: object
     ConversationModelCreateSchema:
       allOf:
@@ -1075,14 +1075,14 @@ components:
       properties:
         conversation:
           $ref: '#/components/schemas/SearchResultConversation'
-        results:
-          items:
-            $ref: '#/components/schemas/MultiSearchResultItem'
-          type: array
         hits:
           items:
             $ref: '#/components/schemas/SearchResultHit'
           type: array
+        results:
+          items:
+            $ref: '#/components/schemas/MultiSearchResultItem'
+          type: array
       required:
         - results
       type: object

typesense/api/generator/main.go

@@ -90,6 +90,9 @@ func processOpenAPISpec(m *yml) {
 	// Remove additionalProperties from SearchResultHit -> document
 	log.Println("Removing additionalProperties from SearchResultHit")
 	searchResultHit(m)
+	// Keep CollectionUpdateSchema -> fields as a plain slice
+	log.Println("Skipping the optional pointer for CollectionUpdateSchema fields")
+	collectionUpdateFields(m)
 	// Extract anonymous structs to named types
 	log.Println("Extracting anonymous structs to named types")
 	extractAnonymousStructs(m)
@@ -147,6 +150,22 @@ func searchResultHit(m *yml) {
 	delete(document, "additionalProperties")
 }
 
+// collectionUpdateFields keeps CollectionUpdateSchema -> fields generated as []Field
+// rather than *[]Field.
+//
+// The collection update endpoint accepts an update that changes only `metadata`, so
+// the spec does not list `fields` as required. oapi-codegen renders an optional array
+// as a pointer, which would break every caller constructing a CollectionUpdateSchema.
+// x-go-type-skip-optional-pointer leaves the slice unwrapped, and `omitempty` is still
+// applied because the property is optional -- so a nil or empty Fields sends no
+// `fields` key at all. That is what the endpoint needs: it rejects both `"fields":null`
+// and `"fields":[]` with a 400.
+func collectionUpdateFields(m *yml) {
+	properties := (*m)["components"].(yml)["schemas"].(yml)["CollectionUpdateSchema"].(yml)["properties"].(yml)
+	fields := properties["fields"].(yml)
+	fields["x-go-type-skip-optional-pointer"] = true
+}
+
 func unwrapDeleteDocument(m *yml) {
 	parameters := (*m)["paths"].(yml)["/collections/{collectionName}/documents"].(yml)["delete"].(yml)["parameters"].([]interface{})
 	deleteParameters := parameters[1].(yml)["schema"].(yml)["properties"].(yml)

typesense/api/generator/openapi.yml

@@ -2479,9 +2479,8 @@ components:
           description: >
             Optional details about the collection, e.g., when it was created, who created it etc.
     CollectionUpdateSchema:
-      required:
-        - fields
       type: object
+      minProperties: 1
       properties:
         fields:
           type: array

typesense/collection_test.go

@@ -2,6 +2,7 @@ package typesense
 
 import (
 	"context"
+	"encoding/json"
 	"errors"
 	"net/http"
 	"testing"
@@ -178,6 +179,46 @@ func TestCollectionUpdate(t *testing.T) {
 	assert.Equal(t, expectedResult, result)
 }
 
+// A collection update that changes only the metadata must not send a `fields` key at
+// all: Typesense rejects both `"fields":null` and `"fields":[]` with a 400. This relies
+// on the `omitempty` tag generated for CollectionUpdateSchema.Fields.
+func TestCollectionUpdateSchemaOmitsEmptyFields(t *testing.T) {
+	tests := []struct {
+		name       string
+		fields     []api.Field
+		wantFields bool
+	}{
+		{
+			name:   "nil fields",
+			fields: nil,
+		},
+		{
+			name:   "empty fields",
+			fields: []api.Field{},
+		},
+		{
+			name:       "populated fields",
+			fields:     []api.Field{{Name: "country", Drop: pointer.True()}},
+			wantFields: true,
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			body, err := json.Marshal(&api.CollectionUpdateSchema{
+				Fields:   tt.fields,
+				Metadata: &map[string]interface{}{"revision": "2"},
+			})
+			assert.NoError(t, err)
+
+			payload := map[string]json.RawMessage{}
+			assert.NoError(t, json.Unmarshal(body, &payload))
+
+			_, hasFields := payload["fields"]
+			assert.Equal(t, tt.wantFields, hasFields, "body: %s", body)
+		})
+	}
+}
+
 func TestCollectionUpdateOnApiClientErrorReturnsError(t *testing.T) {
 	updateSchema := updateExistingSchema()
 

typesense/test/collection_test.go

@@ -58,3 +58,33 @@ func TestCollectionUpdate(t *testing.T) {
 	require.Equal(t, pointer.True(), result.Fields[0].Drop)
 	require.Equal(t, "2", (*result.Metadata)["revision"].(string))
 }
+
+// Updating only the metadata has to leave `fields` out of the request entirely, since
+// Typesense rejects both `"fields":null` and `"fields":[]` with a 400.
+func TestCollectionUpdateMetadataOnly(t *testing.T) {
+	for _, tt := range []struct {
+		name   string
+		fields []api.Field
+	}{
+		{name: "nil fields", fields: nil},
+		{name: "empty fields", fields: []api.Field{}},
+	} {
+		t.Run(tt.name, func(t *testing.T) {
+			collectionName := createNewCollection(t, "companies")
+
+			result, err := typesenseClient.Collection(collectionName).Update(context.Background(),
+				&api.CollectionUpdateSchema{
+					Fields:   tt.fields,
+					Metadata: &map[string]interface{}{"revision": "2"},
+				})
+			require.NoError(t, err)
+			require.Equal(t, "2", (*result.Metadata)["revision"].(string))
+
+			// Confirm the change reached the collection and left the schema alone.
+			updated, err := typesenseClient.Collection(collectionName).Retrieve(context.Background())
+			require.NoError(t, err)
+			require.Equal(t, "2", (*updated.Metadata)["revision"].(string))
+			require.Len(t, updated.Fields, 3)
+		})
+	}
+}