{"record":{"id":"2aee3f08575e059f","repo":"deepset-ai/haystack","slug":"background-color-must-be-a-string","errorCode":null,"errorMessage":"Background color must be a string.","messagePattern":"Background color must be a string\\.","errorType":"validation","errorClass":"ValueError","httpStatus":null,"severity":"error","filePath":"haystack/core/pipeline/draw.py","lineNumber":158,"sourceCode":"\n    if params[\"format\"] == \"img\" and params[\"type\"] not in valid_img_types:\n        raise ValueError(f\"Invalid image type: {params['type']}. Valid options are: {valid_img_types}.\")\n\n    if params[\"theme\"] not in valid_themes:\n        raise ValueError(f\"Invalid theme: {params['theme']}. Valid options are: {valid_themes}.\")\n\n    if \"width\" in params and not isinstance(params[\"width\"], int):\n        raise ValueError(\"Width must be an integer.\")\n    if \"height\" in params and not isinstance(params[\"height\"], int):\n        raise ValueError(\"Height must be an integer.\")\n\n    if \"scale\" in params and not 1 <= params[\"scale\"] <= 3:\n        raise ValueError(\"Scale must be a number between 1 and 3.\")\n    if \"scale\" in params and not (\"width\" in params or \"height\" in params):\n        raise ValueError(\"Scale is only allowed when width or height is set.\")\n\n    if \"bgColor\" in params and not isinstance(params[\"bgColor\"], str):\n        raise ValueError(\"Background color must be a string.\")\n\n    # PDF specific parameters\n    if params[\"format\"] == \"pdf\":\n        if \"fit\" in params and not isinstance(params[\"fit\"], bool):\n            raise ValueError(\"Fit must be a boolean.\")\n        if \"paper\" in params and not isinstance(params[\"paper\"], str):\n            raise ValueError(\"Paper size must be a string (e.g., 'a4', 'a3').\")\n        if \"landscape\" in params and not isinstance(params[\"landscape\"], bool):\n            raise ValueError(\"Landscape must be a boolean.\")\n        if \"fit\" in params and (\"paper\" in params or \"landscape\" in params):\n            logger.warning(\"`fit` overrides `paper` and `landscape` for PDFs. Ignoring `paper` and `landscape`.\")\n\n\n# Magic-byte signatures used to verify a Mermaid server response matches the requested output format.\n_PNG_SIGNATURE = b\"\\x89PNG\\r\\n\\x1a\\n\"\n_JPEG_SIGNATURE = b\"\\xff\\xd8\\xff\"\n_PDF_SIGNATURE = b\"%PDF-\"\n_RIFF_SIGNATURE = b\"RIFF\"","sourceCodeStart":140,"sourceCodeEnd":176,"githubUrl":"https://github.com/deepset-ai/haystack/blob/e318778c9bf60a1963e3b5f451359655dd696c30/haystack/core/pipeline/draw.py#L140-L176","documentation":"The mermaid background color parameter must be a string (e.g. a hex color or color name). Haystack raises this when params['bgColor'] is any non-string value.","triggerScenarios":"params={'bgColor': 0xFFFFFF} (int), {'bgColor': ['#fff']} (list), or None.","commonSituations":"Passing raw RGB integers or tuples from graphics code instead of a hex string like 'FFFFFF' or '!FFFFFF'.","solutions":["Convert to a hex string: params['bgColor'] = f\"{value:06X}\" if it's an int","Use a named color string like 'white' or hex 'FF0000'","Remove 'bgColor' to use the default background"],"exampleFix":"// before\npipeline.draw(path=\"g.png\", params={\"bgColor\": 0xFF0000})  # ValueError\n// after\npipeline.draw(path=\"g.png\", params={\"bgColor\": \"FF0000\"})","handlingStrategy":"type-guard","validationCode":"if \"bgColor\" in params and not isinstance(params[\"bgColor\"], str):\n    params[\"bgColor\"] = str(params[\"bgColor\"])","typeGuard":"def is_str_bg(params: dict) -> bool:\n    return \"bgColor\" not in params or isinstance(params[\"bgColor\"], str)","tryCatchPattern":"try:\n    pipeline.draw(path, params=params)\nexcept ValueError as e:\n    if \"Background color\" in str(e):\n        params[\"bgColor\"] = str(params[\"bgColor\"])\n        pipeline.draw(path, params=params)","preventionTips":["Always pass hex/named color strings","Never pass raw RGB ints or tuples"],"tags":["mermaid","validation","type-error","params"],"backgroundTag":"invalid-parameter-type","analyzedSha":"e318778c9bf60a1963e3b5f451359655dd696c30","analyzedAt":"2026-08-30T11:45:20.711Z","schemaVersion":2},"datasetVersion":"2026-08-30T13:17:10.514Z"}