2 回答

TA贡献2012条经验 获得超12个赞
以下仅使用 JMESPath 语法的情况如何?
product.images.[bigImage, normalImage][?@]|[0]
我们的想法是,我们按照偏好顺序制作一个要使用的所有图像的数组,过滤掉丢失的图像,然后选择剩余数组中的第一个项目。
警告 - 这不会区分缺失值和(或其他“错误”值,例如空字符串),因此,如果这对您的特定情况很重要,则可能需要对其进行一些调整。null

TA贡献1804条经验 获得超8个赞
您可以创建一个类来执行此操作,类似于 GitHub 页面中给出的示例。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))
这将打印出以下结果:
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变得太复杂,我们总是可以使用旧的标准字典方法:
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))
这也打印相同的结果:
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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