Fix UpdateDescription to use read-modify-write pattern (#46)

* fix: handle WriteRune return values in toEnumCase

Satisfy revive unhandled-error linter.

* fix: UpdateDescription uses read-modify-write to preserve audit stamps

DataHub v1.3.0 rejects partial editableDatasetProperties aspects that
are missing created/lastModified audit stamps. Read the existing aspect
first, update the description field, and write back the complete
structure — matching the pattern used by all other write operations.

Closes #45

* test: validate UpdateDescription preserves audit stamps and handles markdown

Add tests for read-modify-write pattern: existing properties with audit
stamps preserved, no existing properties (404 fallback), markdown content
with bold/italic/lists/code, and invalid JSON error handling.

Author: cjimti

pkg/client/options.go

@@ -27,9 +27,9 @@ func toEnumCase(s string) string {
 	for i, r := range runes {
 		// Insert underscore before uppercase if preceded by lowercase
 		if i > 0 && unicode.IsUpper(r) && unicode.IsLower(runes[i-1]) {
-			result.WriteRune('_')
+			_, _ = result.WriteRune('_')
 		}
-		result.WriteRune(unicode.ToUpper(r))
+		_, _ = result.WriteRune(unicode.ToUpper(r))
 	}
 	return result.String()
 }

pkg/client/write.go

@@ -17,25 +17,53 @@ func entityTypeFromURN(urn string) (string, error) {
 	return parsed.EntityType, nil
 }
 
-// UpdateDescription sets the editable description for any entity.
+// editablePropertiesAspect represents the editableDatasetProperties aspect.
+type editablePropertiesAspect struct {
+	Description  string         `json:"description"`
+	Created      *auditStampRaw `json:"created,omitempty"`
+	LastModified *auditStampRaw `json:"lastModified,omitempty"`
+}
+
+// UpdateDescription sets the editable description for any entity using read-modify-write.
 func (c *Client) UpdateDescription(ctx context.Context, urn, description string) error {
 	entityType, err := entityTypeFromURN(urn)
 	if err != nil {
 		return fmt.Errorf("UpdateDescription: %w", err)
 	}
 
-	aspect := map[string]any{
-		"description": description,
+	props, err := c.readEditableProperties(ctx, urn)
+	if err != nil {
+		return fmt.Errorf("UpdateDescription: %w", err)
 	}
 
+	props.Description = description
+
 	return c.postIngestProposal(ctx, ingestProposal{
 		EntityType: entityType,
 		EntityURN:  urn,
 		AspectName: "editableDatasetProperties",
-		Aspect:     aspect,
+		Aspect:     props,
 	})
 }
 
+// readEditableProperties reads the current editableDatasetProperties aspect.
+// Returns an empty aspect if none exists (not an error).
+func (c *Client) readEditableProperties(ctx context.Context, urn string) (*editablePropertiesAspect, error) {
+	raw, err := c.getAspect(ctx, urn, "editableDatasetProperties")
+	if err != nil {
+		if errors.Is(err, ErrNotFound) {
+			return &editablePropertiesAspect{}, nil
+		}
+		return nil, fmt.Errorf("reading editableDatasetProperties: %w", err)
+	}
+
+	var props editablePropertiesAspect
+	if err := json.Unmarshal(raw, &props); err != nil {
+		return nil, fmt.Errorf("parsing editableDatasetProperties: %w", err)
+	}
+	return &props, nil
+}
+
 // globalTagsAspect represents the globalTags aspect structure.
 type globalTagsAspect struct {
 	Tags []tagAssociation `json:"tags"`

pkg/client/write_test.go

@@ -10,8 +10,14 @@ import (
 
 func TestUpdateDescription(t *testing.T) {
 	server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
-		if r.Method != http.MethodPost {
-			t.Errorf("expected POST, got %s", r.Method)
+		if r.Method == http.MethodGet {
+			propsJSON := `{"description":"old desc",` +
+				`"created":{"actor":"urn:li:corpuser:admin","time":1000},` +
+				`"lastModified":{"actor":"urn:li:corpuser:admin","time":2000}}`
+			resp := aspectResponse{Value: json.RawMessage(propsJSON)}
+			w.Header().Set("Content-Type", "application/json")
+			_ = json.NewEncoder(w).Encode(resp)
+			return
 		}
 
 		proposal, aspectJSON := extractProposalWireFormat(t, r.Body)
@@ -23,12 +29,18 @@ func TestUpdateDescription(t *testing.T) {
 			t.Errorf("expected aspect 'editableDatasetProperties', got %v", proposal["aspectName"])
 		}
 
-		var aspectMap map[string]any
-		if err := json.Unmarshal([]byte(aspectJSON), &aspectMap); err != nil {
+		var props editablePropertiesAspect
+		if err := json.Unmarshal([]byte(aspectJSON), &props); err != nil {
 			t.Fatalf("failed to unmarshal inner aspect: %v", err)
 		}
-		if aspectMap["description"] != "new description" {
-			t.Errorf("expected description 'new description', got %v", aspectMap["description"])
+		if props.Description != "new description" {
+			t.Errorf("expected 'new description', got %q", props.Description)
+		}
+		if props.Created == nil || props.Created.Actor != "urn:li:corpuser:admin" {
+			t.Error("expected created audit stamp to be preserved")
+		}
+		if props.LastModified == nil || props.LastModified.Time != 2000 {
+			t.Error("expected lastModified audit stamp to be preserved")
 		}
 
 		w.WriteHeader(http.StatusOK)
@@ -50,6 +62,102 @@ func TestUpdateDescription(t *testing.T) {
 	}
 }
 
+func TestUpdateDescription_NoExistingProperties(t *testing.T) {
+	server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		if r.Method == http.MethodGet {
+			w.WriteHeader(http.StatusNotFound)
+			return
+		}
+		_, aspectJSON := extractProposalWireFormat(t, r.Body)
+		var props editablePropertiesAspect
+		if err := json.Unmarshal([]byte(aspectJSON), &props); err != nil {
+			t.Fatalf("failed to unmarshal inner aspect: %v", err)
+		}
+		if props.Description != "first description" {
+			t.Errorf("expected 'first description', got %q", props.Description)
+		}
+		w.WriteHeader(http.StatusOK)
+	}))
+	defer server.Close()
+
+	c := &Client{
+		endpoint:   server.URL + "/api/graphql",
+		token:      "test-token",
+		httpClient: server.Client(),
+		logger:     NopLogger{},
+	}
+
+	err := c.UpdateDescription(context.Background(),
+		"urn:li:dataset:(urn:li:dataPlatform:hive,testdb.table,PROD)",
+		"first description")
+	if err != nil {
+		t.Fatalf("unexpected error: %v", err)
+	}
+}
+
+func TestUpdateDescription_MarkdownContent(t *testing.T) {
+	mdDesc := "## Overview\n\n**bold** and _italic_\n\n- item 1\n- item 2\n\n`code`"
+
+	server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		if r.Method == http.MethodGet {
+			propsJSON := `{"description":"old",` +
+				`"created":{"actor":"urn:li:corpuser:datahub","time":0},` +
+				`"lastModified":{"actor":"urn:li:corpuser:datahub","time":0}}`
+			resp := aspectResponse{Value: json.RawMessage(propsJSON)}
+			w.Header().Set("Content-Type", "application/json")
+			_ = json.NewEncoder(w).Encode(resp)
+			return
+		}
+		_, aspectJSON := extractProposalWireFormat(t, r.Body)
+		var props editablePropertiesAspect
+		if err := json.Unmarshal([]byte(aspectJSON), &props); err != nil {
+			t.Fatalf("failed to unmarshal inner aspect: %v", err)
+		}
+		if props.Description != mdDesc {
+			t.Errorf("markdown not preserved:\ngot:  %q\nwant: %q",
+				props.Description, mdDesc)
+		}
+		w.WriteHeader(http.StatusOK)
+	}))
+	defer server.Close()
+
+	c := &Client{
+		endpoint:   server.URL + "/api/graphql",
+		token:      "test-token",
+		httpClient: server.Client(),
+		logger:     NopLogger{},
+	}
+
+	err := c.UpdateDescription(context.Background(),
+		"urn:li:dataset:(urn:li:dataPlatform:hive,testdb.table,PROD)",
+		mdDesc)
+	if err != nil {
+		t.Fatalf("unexpected error: %v", err)
+	}
+}
+
+func TestReadEditableProperties_InvalidJSON(t *testing.T) {
+	server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, _ *http.Request) {
+		resp := aspectResponse{Value: json.RawMessage(`not valid json`)}
+		w.Header().Set("Content-Type", "application/json")
+		_ = json.NewEncoder(w).Encode(resp)
+	}))
+	defer server.Close()
+
+	c := &Client{
+		endpoint:   server.URL + "/api/graphql",
+		token:      "test-token",
+		httpClient: server.Client(),
+		logger:     NopLogger{},
+	}
+
+	_, err := c.readEditableProperties(context.Background(),
+		"urn:li:dataset:(urn:li:dataPlatform:hive,testdb.table,PROD)")
+	if err == nil {
+		t.Fatal("expected error for invalid JSON")
+	}
+}
+
 func TestUpdateDescription_InvalidURN(t *testing.T) {
 	c := &Client{logger: NopLogger{}}
 	err := c.UpdateDescription(context.Background(), "not-a-urn", "desc")