如何检查字典中是否存在值，该值是否在另一个字典的列表中？

Question

I have a dictionary that contains multiple keys and values, one of which contains a list of more dictionaries. I need to be able to find if a given value exists within those dictionaries, but I'm unsure how to check against them when they exist not only within a list, but within an object property.

While a for loop check could accomplish this, the property could end up holding hundreds of values, which would make this approach inefficient.

I've also tried variations of: if <value> in <dict>[<list>][<dict2>]

But, I keep getting TypeErrors that list indices must be an integer or slice (The values are strings).

An example of the code would be:

dictExample = {
"name": "yes",
"age": 25,
"Check_Me": [
    {"type": "code", "value": "001"},
    {"type": "code", "value": "002"},
    {"type": "code", "value": "003"},
    {"type": "code", "value": "004"},
    {"type": "code", "value": "005"}
    ],
}

if "007" not in dictExample["Check_Me"]["value"]:
    print("It works!")
else:
    print("Failure...")

(I cannot upload the actual code, but this is roughly what I am facing.)

Expected output would be that the code runs without errors, and is successfully able to find if the value is in the nested dictionary or not.

Answer 1

One example is to use the inbuilt any function which short circuits when the first match is found. However there are several options

if not any("007" in x["value"] for x in dictExample["Check_Me"]):
    print("It works!")

Answer 2

dictExample = {
"name": "yes",
"age": 25,
"Check_Me": [
    {"type": "code", "value": "001"},
    {"type": "code", "value": "002"},
    {"type": "code", "value": "003"},
    {"type": "code", "value": "004"},
    {"type": "code", "value": "005"}
    ],
}
if "007" not in [d['value'] for d in dictExample['Check_Me']]:
    print("It works!")
else:
    print("Failure...")

• Just iterate over Check_Me and get all the values of key 'value' from dictionary.

Answer 3

You may need recursion:

def val_in_dict(my_val, the_dict):
    for value in the_dict.values():
        if my_val == value:
            return True
        elif isinstance(value, list):
            for element in value:
                if isinstance(element, dict) and val_in_dict(my_val, element):
                    return True
    return False
if val_in_dict("007", d):
    print("It works")

You may also want to change a line up there to isinstance(value, (list, tuple)) or something more complicated. Using recursion allows you to be more flexible on how deep your data hierarchy can go.