developing-datacloud-code-extension

SKILL.md

developing-datacloud-code-extension Skill

Overview

This skill provides a complete workflow for developing, testing, and deploying custom Python code extensions to Salesforce Data Cloud. Code extensions allow you to write Python transformations that read from and write to Data Lake Objects (DLOs) and Data Model Objects (DMOs).

When to Use

User wants to create a new code extension project

User needs to test a code extension locally

User wants to scan code for required permissions

User needs to deploy a code extension to Data Cloud

User is working with Data Cloud transformations

User wants to read/write DLO or DMO data programmatically

Prerequisites Check

Before executing any code extension commands, verify prerequisites:

SF CLI with plugin installed

sf plugins --core | grep data-code-extension

If not installed:

sf plugins install @salesforce/plugin-data-codeextension

Python 3.11

python --version  # Should show 3.11.x

Data Cloud Custom Code SDK

pip list | grep salesforce-data-customcode

If not installed:

pip install salesforce-data-customcode

Docker running (for deploy only)

docker ps

Authenticated org

sf org display --target-org <org_alias> --json

Skill Workflow

Phase 1: Initialize Project

Create a new code extension project with scaffolding.

Commands:

For script-based code extensions (batch transformations):

sf data-code-extension script init --package-dir <directory>

For function-based code extensions (real-time):

sf data-code-extension function init --package-dir <directory>

Required Option:

--package-dir, -p - Directory path where the package will be created

What it creates:

my-transform/              # Project root
├── payload/               # CRITICAL: This is what --package-dir must point to for deploy
│   ├── entrypoint.py      # Main transformation code
│   └── config.json        # Code extension configuration
├── requirements.txt       # Python dependencies
└── README.md

Directory Context During Workflow

IMPORTANT: Understanding the directory structure is critical for successful deployment.

Commands and their directory requirements:

Command
Run From
Path/File Argument

init
Parent directory
<project-name> or .

scan
Project root
./payload/entrypoint.py

run
Project root
./payload/entrypoint.py

deploy
Project root
--package-dir ./payload (REQUIRED)

CRITICAL: The --package-dir argument in deploy command MUST point to the payload directory, not the project root.

Phase 2: Develop Transformation

Edit payload/entrypoint.py with transformation logic.

Script Example (Batch):

from datacustomcode import Client

client = Client()

# Read from DLO
df = client.read_dlo('Employee__dll')

# Transform data (uppercase position field)
df['position_upper'] = df['position'].str.upper()

# Write to output DLO
client.write_to_dlo('Employee_Upper__dll', df, 'overwrite')

Function Example (Real-time):

from datacustomcode import FunctionClient

def transform(event, context):
    client = FunctionClient(context)
    input_data = event['data']
    output = {
        'name': input_data['name'].upper(),
        'status': 'processed'
    }
    return output

Common Operations:

client.read_dlo('DLO_Name__dll') - Read from DLO

client.read_dmo('DMO_Name') - Read from DMO

client.write_to_dlo('DLO_Name__dll', df, 'overwrite') - Write to DLO

client.write_to_dmo('DMO_Name', df, 'upsert') - Write to DMO

Phase 3: Scan for Permissions

Scan the entrypoint file to detect required permissions and generate config.json.

Command:

sf data-code-extension script scan --entrypoint ./payload/entrypoint.py

What it detects:

Read permissions for DLOs/DMOs

Write permissions for DLOs/DMOs

Python package dependencies

Updates config.json and requirements.txt

Phase 4: Validate DLO Schema (Pre-Test Check)

CRITICAL: Before running tests locally, validate that all DLOs used in your code exist and have the expected fields.

Step 4a: Extract DLOs from config.json

After scanning, review the generated config.json to identify all DLOs:

cat payload/config.json

Step 4b: Validate Each DLO Schema

Use the getting-datacloud-schema skill to verify DLOs exist and check field names.

For each DLO referenced in your code:

Verify DLO exists:

python3 scripts/get_dlo_schema.py <org_alias> <dlo_name>

Verify field names match — compare fields used in your entrypoint.py against the DLO schema.

Check all DLOs:

Validate all DLOs in read permissions

Validate all DLOs in write permissions

Check field names match exactly (case-sensitive)

Verify data types are compatible with operations

Step 4c: Validation Checklist

Before proceeding to run, ensure:

 All DLOs in config.json exist in target org

 All field names used in code exist in DLO schemas

 Field data types match your transformation logic

 Primary key fields are correctly identified

 Write target DLOs are created and accessible

Phase 5: Test Locally

After validating DLO schemas, run the code extension locally against your Data Cloud org.

Command:

sf data-code-extension script run --entrypoint <entrypoint_file> --target-org <org_alias> [options]

Options:

--target-org, -o - SF CLI org alias (required)

--config-file, -c - Custom config file path

If you get errors:

Re-validate DLO schemas

Check field names are exact matches

Verify data types are compatible

Review error messages for field/DLO issues

Phase 6: Deploy to Data Cloud

Deploy the code extension to Data Cloud for scheduled or on-demand execution.

CRITICAL: You MUST specify --package-dir ./payload to point to the payload directory created by init.

Command:

sf data-code-extension script deploy --target-org <org_alias> --name <name> --package-dir ./payload --package-version <version> --description <description> [options]

Required Options:

--target-org, -o - SF CLI org alias

--name, -n - Name for code extension deployment

--package-dir - Path to payload directory (REQUIRED - must be ./payload when running from project root)

--package-version - Version string (default: 0.0.1)

--description - Description of code extension

Optional Options:

--cpu-size - CPU size: CPU_L, CPU_XL, CPU_2XL (default), CPU_4XL

--function-invoke-opt - Function invoke options (for function type)

--network - Docker network (default: default)

After deployment:

Navigate to Data Cloud in Salesforce UI

Go to Data Transforms section

Find your deployment by name

Click "Run Now" to execute

Schedule for recurring execution

Error Handling

Common Issues and Solutions

Error
Solution

command data-code-extension not found
sf plugins install @salesforce/plugin-data-codeextension

datacustomcode CLI not found
pip install salesforce-data-customcode

Python version mismatch
Use pyenv: pyenv install 3.11.0 && pyenv local 3.11.0

Cannot connect to Docker daemon
Start Docker Desktop

No org found for alias
sf org login web --alias <org_alias>

config.json not found
sf data-code-extension script scan --entrypoint ./payload/entrypoint.py

DLO not found
Verify DLO exists (use getting-datacloud-schema skill), check spelling and __dll suffix

Permission denied writing
Re-run scan, verify target DLO exists and is writable

Deploy fails - wrong directory
Ensure --package-dir points to payload/ directory, not project root

Best Practices

Development

Always scan before testing — run scan after code changes

Test locally first — use run command before deploying

Use version control — git commit after each successful test

Version your deployments — use semantic versioning (1.0.0, 1.1.0, etc.)

Deploy from project root with --package-dir ./payload

Performance

CPU_L: Small datasets (< 1M records)

CPU_2XL: Medium datasets (1M-10M records)

CPU_4XL: Large datasets (> 10M records)

Security

No hardcoded credentials — use SF CLI authentication only

Validate input data — check for nulls and data types

Limit write permissions — only grant necessary DLO/DMO access

Integration with Other Skills

Use with getting-datacloud-schema skill (CRITICAL for validation):

The getting-datacloud-schema skill is required for validating DLOs before testing code extensions.

Use with Datakit Workflow:

Create DLO via code extension

Map DLO to DMO using datakit workflow

Use DMO in segments and activations

Command Reference

Command
Purpose
Required Args

script init
Create new script project
--package-dir

function init
Create new function project
--package-dir

script scan
Generate config
entrypoint file

script run
Test locally
entrypoint file, --target-org

script deploy
Deploy to Data Cloud
--target-org, --name, --package-dir, --package-version, --description

Resources

SF CLI Plugin: https://github.com/salesforcecli/plugin-data-code-extension

Python SDK: https://github.com/forcedotcom/datacloud-customcode-python-sdk

Data Cloud Docs: https://help.salesforce.com/s/articleView?id=sf.c360_a_intro.htm

Python SDK PyPI: https://pypi.org/project/salesforce-data-customcode/

Notes

Code extensions run in isolated Python 3.11 environment

Docker is required only for deployment, not for local testing

Use SF CLI authentication only (no separate credential files)

Scan command auto-detects permissions from code

Local run uses actual Data Cloud data (not mocked)

Deployments are versioned and can be rolled back in UI