Python、Flask - 类型错误：字符串索引索引必须是整数或切片，而不是字符串

Question

Goal: Print out the values of a dictionary via a for loop

Here is a recreated version of the code as reference (not the actual code, works just the same):

import networkx as nx
random_dictionary = {
"name": "DAG",
"children": "None",
"father": "None",
"mother": "None",
"spouse": "None",
}

serializable_format = random_dictionary

for n in serializable_format:
    print("[+] node: " + n + ", edge: " + str(serializable_format[n]['pre_transactions']))
    for x in serializable_format[n]['pre_transactions']:
        ledger.add_edge(n, x)

When I execute it, I am constantly met with the following error...

TypeError: string index indices must be integers or slices, not str

I can not insert an integer in the [n] section, as that would give me the following error

KeyError: (insert any number here)

So how do I go about making a for loop which gets the content from the dictionary without encountering any errors?

Answer 1

The problem is that serializable_format[n] is a string ("DAG", 'None", etc). The expression serializable_format[n]['pre_transactions'] tries to use the string 'pre_transactions' for indexing the first string, raising a TypeError . Re-check your code, because you are mistaken those strings with sone other type (like dicts).