URL查询参数与JSON API技术疑问：参数映射、规则及语法差异

Great questions! Let’s break each one down clearly:

1. How do I return a specific value based on the JSON object’s property? #

Once you’ve fetched and parsed the JSON response from the API (most languages/libraries handle parsing automatically, like response.json() in Python or JSON.parse() in JavaScript), you can access the exact value you need using the property name from the JSON object.

For example, if the API returns:

{"parm1_name": "val1", "user_email": "test@example.com"}

In JavaScript:

const response = await fetch("your-api-url-here");
const data = await response.json();
const myValue = data.parm1_name; // Returns "val1"
const userEmail = data["user_email"]; // Alternative bracket notation, useful for names with spaces/symbols

In Python:

import requests
response = requests.get("your-api-url-here")
data = response.json()
my_value = data["parm1_name"] # Gets "val1"

Just use the exact property name from the JSON output to grab the value you want.

2. Do I have to use the official parameter names provided by the API? #

Yes, 100%—you can’t make up your own parameter names here. APIs are programmed to only recognize the specific query parameters listed in their documentation. If you use a different name (like my_param instead of parm1), the server won’t know what to do with it. It might ignore the invalid parameter and return a default response, or even throw a 400 Bad Request error.

Always follow the API’s guide for parameter names—those are the only ones the backend is set up to process.

3. What’s the difference between ?param1=val and param1=:val? #

These are two different things entirely:

• ?param1=val: This is a standard query parameter in a URL. The ? starts the query string, param1 is the parameter name, and val is the literal value you’re sending to the API. For example, https://api.example.com/products?category=books sends the value "books" for the category parameter.
• param1=:val: The :val part is not a valid value to send directly. This is a placeholder syntax used in:
  • API client tools (Postman, Insomnia) to mark where a dynamic variable should go (you’d replace :val with an actual value like 123 before sending the request).
  • Documentation or code templates to show that a value needs to be substituted. For example, if you see ?user_id=:id, you’d swap :id with a real user ID to get ?user_id=456.

You never send :val in a real request—you always replace it with the actual value you want to pass.

内容的提问来源于stack exchange，提问作者Hana90