fix(grammars): handle empty parameters on object types (#6409)

fix: handle empty parameters on object types

Signed-off-by: Ettore Di Giacinto <mudler@localai.io>

pkg/functions/grammars/json_schema.go

@@ -171,10 +171,14 @@ func (sc *JSONSchemaConverter) visit(schema map[string]interface{}, name string,
 		}
 		rule := fmt.Sprintf(`"[" space (%s ("," space %s)*)? "]" space`, itemRuleName, itemRuleName)
 		return sc.addRule(ruleName, rule), nil
+	} else if properties, _ := schema["properties"].(map[string]interface{}); (schemaType == "object" || schemaType == "") && len(properties) == 0 {
+		// Handle empty object schema (no properties)
+		rule := `"{" space "}" space`
+		return sc.addRule(ruleName, rule), nil
 	} else {
 		primitiveRule, exists := PRIMITIVE_RULES[schemaType]
 		if !exists {
-			return "", fmt.Errorf("unrecognized schema: %v", schema)
+			return "", fmt.Errorf("unrecognized schema: %v (type: %s)", schema, schemaType)
 		}
 		if ruleName == "root" {
 			schemaType = "root"

pkg/functions/grammars/json_schema_test.go

@@ -442,5 +442,39 @@ realvalue
 				}
 			}
 		})
+
+		It("handles empty object schema without properties", func() {
+			// Test case for the bug fix: schema with empty properties map
+			emptyObjectSchema := `{
+				"type": "object",
+				"properties": {}
+			}`
+
+			grammar, err := NewJSONSchemaConverter("").GrammarFromBytes([]byte(emptyObjectSchema))
+			Expect(err).To(BeNil())
+			Expect(grammar).To(ContainSubstring(`root ::= "{" space "}" space`))
+		})
+
+		It("handles object schema without properties field", func() {
+			// Test case for object schema without properties field at all
+			objectWithoutProperties := `{
+				"type": "object"
+			}`
+
+			grammar, err := NewJSONSchemaConverter("").GrammarFromBytes([]byte(objectWithoutProperties))
+			Expect(err).To(BeNil())
+			Expect(grammar).To(ContainSubstring(`root ::= "{" space "}" space`))
+		})
+
+		It("handles schema with properties but no type field", func() {
+			// Test case for the exact scenario causing the panic: schema with properties but no type
+			schemaWithPropertiesNoType := `{
+				"properties": {}
+			}`
+
+			grammar, err := NewJSONSchemaConverter("").GrammarFromBytes([]byte(schemaWithPropertiesNoType))
+			Expect(err).To(BeNil())
+			Expect(grammar).To(ContainSubstring(`root ::= "{" space "}" space`))
+		})
 	})
 })