“TypeError：列表索引必须是整数，而不是 str”：yaml.load_all？

Question

我要解析具有以下数据结构的 YAML 文件：

    Version: 1
    TxnCode: MPT
    MessageID: "FFH-18544-1388620740-795905"
    Recommendations: 
     - {ReqSegFlightRef: [[1,2]],TotalPriceRef: 1,PriceInfoRef: 1}
     - {ReqSegFlightRef: [[3,4,2]],TotalPriceRef: 2,PriceInfoRef: 2}
     - {ReqSegFlightRef: [[5,4,2]],TotalPriceRef: 3,PriceInfoRef: 3}
    Flights: 
     - {OpCarrier: SN,MktCarrier: SN,FlightNb: 2902,DptDate: "0109",DptTime:     "09:30",ArrTime: "11:05",DptAirport: VIE,ArrAirport: BRU}
     - {OpCarrier: SN,MktCarrier: SN,FlightNb: 243,DptDate: "0109",DptTime: "12:15",ArrTime: "17:00",DptAirport: BRU,ArrAirport: FNA}
     - {OpCarrier: OS,MktCarrier: LH,FlightNb: 6325,DptDate: "0109",DptTime: "06:30",ArrTime: "07:35",DptAirport: VIE,ArrAirport: MUC}
    Prices: 
     - {TotalPrice: 1574.14,BaseAmount: 1368.00,TotalTaxe: 206.14,TotalSurcharge: 0.00,TotalFee: 0.00}
     - {TotalPrice: 1633.57,BaseAmount: 1368.00,TotalTaxe: 265.57,TotalSurcharge: 0.00,TotalFee: 0.00}
     - {TotalPrice: 1636.57,BaseAmount: 1368.00,TotalTaxe: 268.57,TotalSurcharge: 0.00,TotalFee: 0.00}
  LFSDetails: |
    PriceInfos: 
     - {FaresRef: [1,2],Price: {Total: 1574.14},Amount: {Total: 1368.00},Taxes:  {Total: 206.14},Surcharges: {Total: 0.00},Fees: {Total: 0.00}}
     - {FaresRef: [3,4,2],Price: {Total: 1633.57},Amount: {Total: 1368.00},Taxes: {Total: 265.57},Surcharges: {Total: 0.00},Fees: {Total: 0.00}}
     - {FaresRef: [3,4,2],Price: {Total: 1636.57},Amount: {Total: 1368.00},Taxes: {Total: 268.57},Surcharges: {Total: 0.00},Fees: {Total: 0.00}}
    ListCabinRequested: []
    FareInfo: 
     - {RBD: M,FareBasis: BFFOWAT,PTC: ADT,BreakPointId: N,Availability: 9,Cabin: W,FareType: OB}
     - {RBD: B,FareBasis: BFFOWAT,PTC: ADT,BreakPointId: Y,Availability: 9,Cabin: W,FareType: OB}
     - {RBD: B,FareBasis: BFFOWAT,PTC: ADT,BreakPointId: N,Availability: 9,Cabin: M,FareType: OB}
    Currency: EUR

我有以下代码，但在第 20 行出现“TypeError：列表索引必须是整数，而不是 str”：

def yaml_load_all(iStream,iCodeFilter=None):
    for ayamldoc in yaml.load_all(iStream):
        lfsWrapper = LFSWrapper(iCodeFilter)
        lfsDetails = ayamldoc['LFSDetails'] #line 20
        if lfsDetails is not None:
            ayamldoc['LFSDetails'] = yaml.load(lfsDetails)
        lfsWrapper.loadDict(ayamldoc)
        if lfsWrapper.isValid():
            yield lfsWrapper

（我稍后会调用此方法，将 iStream 设置为 sys.stdin 以读取数据文件）。

我认为我在这里缺少一些关于数据结构或 yaml.load_all 工作方式的基本内容。

我错过了什么？

Answer 1

我猜你正在使用 PyYaml。

load_all 用于在单个文件中加载多个 YAML 文档，因此总是返回一个列表。你只有一个文档，它映射到一个 Python 字典，所以你应该只使用 load。

Answer 2

如果不是无效的 YAML 文件，您的示例很奇怪，这使得它有点猜测这里发生了什么。它是一个有问题的 YAML 文件的原因是

LFSDetails: |

与之前和之后的行相比，缩进不同（即缩进）的行。

直到LFSDetails，YAML 文件看起来好像在顶层有一个映射。因此，最初的解决方案可能只是将LFSDetails 推入两个空格以使其与之对齐。这将导致一个空字符串作为其文字块标量（与 | 一起引入，并且您的代码似乎依赖 YAML 作为 YAML 中的文本块。所以看起来LFSDetails 后面的所有行后面的缩进是正确的。

要显示您的错误消息，您的 YAML 文件必须以短划线（序列指示符）开头，缩进 3 个空格：

   -
    Version: 1
  LFSDetails: |
    PriceInfos:
     - {FaresRef: [1,2],Price: {Total: 1574.14},Amount: {Total: 1368.00},Taxes:  {Total: 206.14},Surcharges: {Total: 0.00},Fees: {Total: 0.00}}

给出了这个错误（我去掉了不相关的中间映射条目）。然而，这会解析，但在LFSDetails ¹ 的压痕之后完全丢弃任何东西：

import ruamel.yaml as yaml

yaml_str = """\
   -
    Version: 1
  LFSDetails: |
    PriceInfos:
     - {FaresRef: [1,2],Price: {Total: 1574.14},Amount: {Total: 1368.00},Taxes:  {Total: 206.14},Surcharges: {Total: 0.00},Fees: {Total: 0.00}}
"""

for data in yaml.load_all(yaml_str):
    print(data)
    print data['LFSDetails']

给你：

[{'Version': 1}]
Traceback (most recent call last):
  File "try.py", line 54, in <module>
    print data['LFSDetails']
TypeError: list indices must be integers, not str

由于破折号，以Version: 开头的映射是序列/列表的第一个元素，然后尝试使用字符串 (LFSDetails) 访问列表元素会得到错误。

因此，您应该首先清理您的 YAML 以使其正确。我还建议包含start of document marker (---)，即使您在示例文件中只有一个文档，因为您使用的是load_all()。并摆脱额外的缩进（即从该行的第一列开始）。删除任何虚假序列开始破折号后，得到如下内容：

import ruamel.yaml as yaml

yaml_str = """\
---
Version: 1
TxnCode: MPT
MessageID: "FFH-18544-1388620740-795905"
Recommendations:
 - {ReqSegFlightRef: [[1,2]],TotalPriceRef: 1,PriceInfoRef: 1}
 - {ReqSegFlightRef: [[3,4,2]],TotalPriceRef: 2,PriceInfoRef: 2}
 - {ReqSegFlightRef: [[5,4,2]],TotalPriceRef: 3,PriceInfoRef: 3}
Flights:
 - {OpCarrier: SN,MktCarrier: SN,FlightNb: 2902,DptDate: "0109",DptTime:     "09:30",ArrTime: "11:05",DptAirport: VIE,ArrAirport: BRU}
 - {OpCarrier: SN,MktCarrier: SN,FlightNb: 243,DptDate: "0109",DptTime: "12:15",ArrTime: "17:00",DptAirport: BRU,ArrAirport: FNA}
 - {OpCarrier: OS,MktCarrier: LH,FlightNb: 6325,DptDate: "0109",DptTime: "06:30",ArrTime: "07:35",DptAirport: VIE,ArrAirport: MUC}
Prices:
 - {TotalPrice: 1574.14,BaseAmount: 1368.00,TotalTaxe: 206.14,TotalSurcharge: 0.00,TotalFee: 0.00}
 - {TotalPrice: 1633.57,BaseAmount: 1368.00,TotalTaxe: 265.57,TotalSurcharge: 0.00,TotalFee: 0.00}
 - {TotalPrice: 1636.57,BaseAmount: 1368.00,TotalTaxe: 268.57,TotalSurcharge: 0.00,TotalFee: 0.00}
LFSDetails: |
  PriceInfos:
   - {FaresRef: [1,2],Price: {Total: 1574.14},Amount: {Total: 1368.00},Taxes:  {Total: 206.14},Surcharges: {Total: 0.00},Fees: {Total: 0.00}}
   - {FaresRef: [3,4,2],Price: {Total: 1633.57},Amount: {Total: 1368.00},Taxes: {Total: 265.57},Surcharges: {Total: 0.00},Fees: {Total: 0.00}}
   - {FaresRef: [3,4,2],Price: {Total: 1636.57},Amount: {Total: 1368.00},Taxes: {Total: 268.57},Surcharges: {Total: 0.00},Fees: {Total: 0.00}}
  ListCabinRequested: []
  FareInfo:
   - {RBD: M,FareBasis: BFFOWAT,PTC: ADT,BreakPointId: N,Availability: 9,Cabin: W,FareType: OB}
   - {RBD: B,FareBasis: BFFOWAT,PTC: ADT,BreakPointId: Y,Availability: 9,Cabin: W,FareType: OB}
   - {RBD: B,FareBasis: BFFOWAT,PTC: ADT,BreakPointId: N,Availability: 9,Cabin: M,FareType: OB}
  Currency: EUR
"""

for data in yaml.load_all(yaml_str):
    lfs_data =  data['LFSDetails']
    nested_data = yaml.load(lfs_data)
    print(type(nested_data))
    print(nested_data['FareInfo'][1]['BreakPointId'])

将你作为输出：

<type 'dict'>
Y

---

¹ _{这是使用ruamel.yaml 完成的，我是其中的作者。它是 PyYAML 的增强版本，使用它的结果应该是相似的。}