如果条目已存在，则将项目添加到 dict 中的列表

Question

我收到了许多包含不同产品订单的 CSV 文件。这些 CSV 文件需要“转换”为特定的 JSON 结构。

CSV 文件的每一行代表一个产品的订单。这意味着如果我要订购两种产品，CSV 将包含两行。

CSV 文件的简化版本可能如下所示（请注意第一行和第三行中的orderId“111”）：

orderId,itemNumber,itemName,name,street
111,123,testitem,john doe,samplestreet 1
222,345,anothertestitem,jane doe,samplestreet 1
111,345,anothertestitem,john doe,samplestreet 1

我当前的解决方案有效，但我认为我过于复杂了。

目前，我正在遍历每个 CSV 行并创建 JSON 结构，其中我使用一个辅助函数，该函数将添加订单或附加一个包含有序项目的列表，如下所示：

def add_orderitem(orderitem, order, all_orders):
    """ Adds an ordered product to the order or "create" a new order if it doesn't exist """
    for row in all_orders:
        # Order already exists
        if any(order["orderNumber"] == value for field, value in row.items()):
            print(f"Order '{order['orderNumber']}' already exists, adding product #{orderitem['sku']}")
            row["orderItems"].append(orderitem)
            return all_orders

    # New order
    print(f"New Order found, creating order '{order['orderNumber']}' and adding product #{orderitem['sku']}")
    all_orders.append(order)
    order["orderItems"].append(orderitem)
    return all_orders


def parse_orders():
    """ Converts CSV-orders into JSON """
    results = []
    orders = read_csv("testorder.csv")  # helper-function returns CSV-dictreader (list of dicts)
    for order in orders:
        # Create basic structure
        orderdata = {
            "orderNumber": order["orderId"],
            "address": {
                "name": order["orderId"],
                "street": order["street"]
            },
            "orderItems": []  # <-- this will be filled later
        }

        # Extract product-information that will be inserted in above 'orderItems' list
        product = {
            "sku": order["itemNumber"],
            "name": order["itemName"]
        }

        # Add order to final list or add item if order already exists
        results = add_orderitem(product, orderdata, results)

    return results


def main():
    from pprint import pprint
    parsed_orders = parse_orders()

    pprint(parsed_orders)


if __name__ == "__main__":
    main()

脚本工作正常，下面的输出是我所期待的：

New Order found, creating order '111' and adding product #123
New Order found, creating order '222' and adding product #345
Order '111' already exists, adding product #345
[{'address': {'name': '111', 'street': 'samplestreet 1'},
  'orderItems': [{'name': 'testitem', 'sku': '123'},
                 {'name': 'anothertestitem', 'sku': '345'}],
  'orderNumber': '111'},
 {'address': {'name': '222', 'street': 'samplestreet 1'},
  'orderItems': [{'name': 'anothertestitem', 'sku': '345'}],
  'orderNumber': '222'}]

有没有办法“更聪明”地做到这一点？

Answer 1

Imo namedtuple 和 groupby 会让你的代码更清晰：

from collections import namedtuple
from itertools import groupby

# csv data or file
data = """orderId,itemNumber,itemName,name,street
111,123,testitem,john doe,samplestreet 1
222,345,anothertestitem,jane doe,samplestreet 1
111,345,anothertestitem,john doe,samplestreet 1
"""

# the Order tuple
Order = namedtuple('Order', 'orderId itemNumber itemName name street')

# load the csv into orders
orders = [Order(*values) for line in data.split("\n")[1:] if line for values in [line.split(",")]]

# and group it by orderId
orders = sorted(orders, key = lambda order: order.orderId)

# group it by orderId
output = list()
for key, values in groupby(orders, key=lambda order: order.orderId):
    items = list(values)
    dct = {"address": {"name": items[0].name, "street": items[0].street},
           "orderItems": [{"name": item.itemName, "sku": item.itemNumber} for item in items]}
    output.append(dct)

print(output)

这会产生

[{'address': {'name': 'john doe', 'street': 'samplestreet 1'}, 'orderItems': [{'name': 'testitem', 'sku': '123'}, {'name': 'anothertestitem', 'sku': '345'}]},
 {'address': {'name': 'jane doe', 'street': 'samplestreet 1'}, 'orderItems': [{'name': 'anothertestitem', 'sku': '345'}]}]

你甚至可以把它放在一个很好的理解中，但这不会使它更具可读性。