例如，有一些包含一些產品數據的 JSON：{ "sku": 123, "product": { "name": "Some name", "images": { "normalImage": "http://somelink.com/1.jpg", "bigImage": "http://somelink.com/1b.jpg" } }}我想選擇圖像鏈接，但僅存在于某些產品中，因此有時我需要選擇。bigImagenormalImage顯而易見的解決方案是這樣的：jmespath.search('product.images.bigImage') or jmespath.search('product.images.normalImage')但我覺得可以做得更好。如何使用 JMESPath 語法以最佳方式執行此操作？
2 回答
繁花如伊
TA貢獻2012條經驗 獲得超12個贊
以下僅使用 JMESPath 語法的情況如何？
product.images.[bigImage, normalImage][?@]|[0]
我們的想法是，我們按照偏好順序制作一個要使用的所有圖像的數組，過濾掉丟失的圖像，然后選擇剩余數組中的第一個項目。
警告 - 這不會區分缺失值和（或其他“錯誤”值，例如空字符串），因此，如果這對您的特定情況很重要，則可能需要對其進行一些調整。null
胡說叔叔
TA貢獻1804條經驗 獲得超8個贊
您可以創建一個類來執行此操作，類似于 GitHub 頁面中給出的示例。CustomFunctions
from jmespath import search
from jmespath import functions
from jmespath import Options
from json import loads
class CustomFunctions(functions.Functions):
# Method that selects 'bigImage' key value if it exists
# Otherwise return 'normalImage' value
# dict.get() is perfect for this, since it returns a default value if a key doesn't exist
# Use type 'object' since thats the equivalant type to a Python dictionary in JSON
# Make sure to decorate function signature as well to indicate types
# Make sure to also put _func_ before your function name
@functions.signature({'types': ['object']})
def _func_choose_key(self, d):
return d.get('bigImage', d['normalImage'])
if __name__ == "__main__":
# Get custom function options
options = Options(custom_functions=CustomFunctions())
# Test method which runs JMESPath query with custom function
def test(json):
json_dict = loads(json)
return search('product.images | choose_key(@)', json_dict, options=options)
# TEST 1 - bigImage key exists
json1 = """{
"sku": 123,
"product": {
"name": "Some name",
"images": {
"normalImage": "http://somelink.com/1.jpg",
"bigImage": "http://somelink.com/1b.jpg"
}
}
}"""
print("Test1: %s" % test(json1))
# TEST 2 - bigImage key doesn't exist
json2 = """{
"sku": 123,
"product": {
"name": "Some name",
"images": {
"normalImage": "http://somelink.com/1.jpg"
}
}
}"""
print("Test2: %s" % test(json2))
這將打印出以下結果：
Test1: http://somelink.com/1b.jpg # When bigImage key exists
Test2: http://somelink.com/1.jpg # When bigImage key doesn't exist
如果JMESPath變得太復雜，我們總是可以使用舊的標準字典方法：
def test2(json):
json_dict = loads(json)
images = json_dict["product"]["images"]
return images.get("bigImage", images["normalImage"])
# TEST 1 - bigImage key exists
json1 = """{
"sku": 123,
"product": {
"name": "Some name",
"images": {
"normalImage": "http://somelink.com/1.jpg",
"bigImage": "http://somelink.com/1b.jpg"
}
}
}"""
print("Test1: %s" % test2(json1))
# TEST 2 - bigImage key doesn't exist
json2 = """{
"sku": 123,
"product": {
"name": "Some name",
"images": {
"normalImage": "http://somelink.com/1.jpg"
}
}
}"""
print("Test2: %s" % test2(json2))
這也打印相同的結果：
Test1: http://somelink.com/1b.jpg # When bigImage key exists
Test2: http://somelink.com/1.jpg # When bigImage key doesn't exist
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