base64_decode_toarray
This page explains how to use the base64_decode_toarray function in APL.
Use the base64_decode_toarray function to decode a Base64-encoded string into an array of bytes. This is especially useful when you need to extract raw binary data from encoded inputs, such as network payloads, authentication tokens, or structured log fields. You can then transform or analyze the resulting byte array using additional APL functions like array_slice, array_length, or array_index.
This function is useful in scenarios where logs or telemetry data include fields that store binary data encoded as Base64, which is common for compact transmission or obfuscation. By decoding these values into byte arrays, you gain visibility into the underlying structure of the data.
Usage
Syntax
base64_decode_toarray(base64_input)Parameters
| Name | Type | Required | Description |
|---|---|---|---|
| base64_input | string | ✓ | A Base64-encoded string. |
Returns
An array of integers representing the decoded byte values. If the input string isn't valid Base64, the function returns an empty array.
Use case examples
You want to decode a Base64-encoded field in logs to inspect raw payloads for debugging or transformation.
Query
['sample-http-logs']
| extend raw = base64_decode_toarray('aGVsbG8gd29ybGQ=')Output
| raw |
|---|
| [104, 101, 108, 108, 111, 32, 119, 111, 114, 108, 100] |
This query decodes the Base64 string 'aGVsbG8gd29ybGQ=', which represents the ASCII string "hello world", into an array of byte values.
You receive Base64-encoded trace IDs from an external system and want to decode them for low-level correlation.
Query
['otel-demo-traces']
| extend trace_bytes = base64_decode_toarray(trace_id)
| project trace_id, trace_bytesOutput
| trace_id | trace_bytes |
|---|---|
| dHJhY2UtaWQtZGVtbw== | [116, 114, 97, 99, 101, 45, 105, 100, 45, 100, 101, 109, 111] |
This query decodes the trace ID from Base64 into its byte-level representation for internal processing or fingerprinting.
List of related functions
- array_length: Returns the number of elements in an array. Use after decoding to validate payload length.
- array_slice: Extracts a subrange from an array. Use to focus on specific byte segments after decoding.
- base64_encode_fromarray: Converts a sequence of bytes into a Base64-encoded string.