Python json.decoder.JSONArray() Function

The Pythonjson.decoder.JSONArray() function is an internal helper function used to parse JSON arrays.

This function is primarily used by the JSON decoder when parsing array structures from a JSON-encoded string.

Syntax

Following is the syntax of the Pythonjson.decoder.JSONArray() function −

json.decoder.JSONArray(s_and_end, scan_once, **kwargs)

Parameters

This function accepts the following parameters −

• s_and_end: A tuple containing the JSON string and the index position to start parsing.
• scan_once: A function used for scanning JSON values.
• **kwargs: Additional keyword arguments.

Return Value

This function returns a tuple containing the parsed list and the index position where parsing stopped.

Example: Basic Usage

In this example, we use thejson.decoder.JSONArray() function to parse a JSON array −

import json.decoder# JSON-encoded arrayjson_string = '[1, 2, 3]'# Define scan_once function properlyscan_once = json.decoder.JSONDecoder().scan_once# Parse JSON array using JSONArray()parsed_array, end_index = json.decoder.JSONArray((json_string, 1), scan_once)print("Parsed Array:", parsed_array)print("End Index:", end_index)

Following is the output of the above code −

Parsed Array: [1, 2, 3]End Index: 9

Example: Parsing Nested JSON Arrays

TheJSONArray() function can also handle nested JSON arrays −

import json.decoder# JSON-encoded nested arrayjson_string = '[[1, 2], [3, 4]]'# Get the scan_once function from JSONDecoderscan_once = json.decoder.JSONDecoder().scan_once# Parse JSON array using JSONArray()parsed_array, end_index = json.decoder.JSONArray((json_string, 1), scan_once)print("Parsed Nested Array:", parsed_array)print("End Index:", end_index)

Following is the output obtained −

Parsed Nested Array: [[1, 2], [3, 4]]End Index: 16

Example: Handling Empty JSON Arrays

The function correctly handles empty JSON arrays −

import json.decoder# JSON-encoded empty arrayjson_string = '[]'# Define scan_once functiondef scan_once(s, idx):   return json.decoder.scanstring(s, idx)# Parse JSON arrayparsed_array, end_index = json.decoder.JSONArray((json_string, 1), scan_once)print("Parsed Empty Array:", parsed_array)print("End Index:", end_index)

We get the output as shown below −

Parsed Empty Array: []End Index: 2

Example: Handling Invalid JSON Arrays

If the input is not a valid JSON array, aValueError is raised −

import json.decoder# Invalid JSON-encoded array (missing closing bracket)json_string = '[1, 2, 3'# Get the scan_once function from JSONDecoderscan_once = json.decoder.JSONDecoder().scan_oncetry:   # Attempt to parse an invalid JSON array   parsed_array, end_index = json.decoder.JSONArray((json_string, 1), scan_once)   print("Parsed Array:", parsed_array)except ValueError as e:   print("Error:", e)

The result produced is as follows −

Error: Expecting ',' delimiter: line 1 column 9 (char 8)