IBMi Field length Change Impact Analysis

A VS Code extension that analyzes the impact of changing a field length in an IBM i physical file. It instantly shows every dependent object — logical files, indexes, triggers, SQL routines, and programs — that will need attention before and after an ALTER TABLE or file change.

Features

• Right-click integration — invoke directly from the IBM i Object Browser on any *FILE object
• Command Palette support — run from anywhere with Ctrl+Shift+P
• Field picker — select from a list of all columns in the file, showing current type and length
• Quick Scan — SQL-based, returns in seconds: logical files, indexes, triggers, SQL procedures/functions
• Deep Scan — additionally runs DSPPGMREF on the library to find every *PGM and *SRVPGM that compiles against the file
• Visual report — styled webview panel with impact grouped by object type, certainty badges, and a full column structure table
• Copy to clipboard — export the file structure table with one click

Prerequisites

The extension uses the active IBM i connection managed by Code for IBM i. No separate connection setup is required.

Installation

From VSIX file

1. Open VS Code
2. Go to Extensions (Ctrl+Shift+X)
3. Click the ··· menu (top-right of the Extensions panel) → Install from VSIX…
4. Select ibmi-field-impact-analysis-1.0.0.vsix

Or via the terminal:

code --install-extension ibmi-field-impact-analysis-1.0.0.vsix

Usage

From the IBM i Object Browser (right-click)

1. Expand your library in the Object Browser panel (provided by Code for IBM i)
2. Right-click any *FILE object
3. Select Analyze Field Length Change Impact

The extension reads the library and file name from the selected item automatically.

From the Command Palette

1. Press Ctrl+Shift+P
2. Type IBMi Field Impact or Analyze Field Length
3. Select IBMi Field Impact: Analyze Field Length Change Impact
4. Enter the library name when prompted (e.g. MYLIB)
5. Enter the physical file name when prompted (e.g. CUSTMAST)

Step-by-step Walkthrough

Once a file is identified (either from the Object Browser or entered manually), the extension guides you through four quick steps:

Step 1 ── Pick the field being changed
          Shows all columns with current type and length

Step 2 ── Enter the new length
          Validates it is a positive integer different from the current length

Step 3 ── Choose scan depth
          Quick Scan  ─ SQL catalog only (seconds)
          Deep Scan   ─ SQL + DSPPGMREF cross-reference (slower, more complete)

Step 4 ── View the impact report
          Opens in a new editor tab

Understanding the Report

The report groups dependent objects into sections:

Definitive means the dependency is confirmed by system catalog data.
Potential means the object is in the same library and may reference the file — manual verification is recommended.

Summary Cards

The top of the report shows:

• Total Dependents — all objects found
• Definitive — confirmed dependencies (green)
• Potential — objects to verify (amber)
• Object Types — number of distinct categories affected

Quick Scan vs Deep Scan

The Deep Scan writes a temporary outfile to QTEMP during the run and deletes it when done.

Building from Source

Requirements

• Node.js 18 or later
• npm

Setup

git clone <repo-url>
cd ibmi-field-impact-analysis
npm install

Commands

Project Structure

src/
├── extension.ts              # Extension entry point — registers commands
├── commands/
│   └── analyzeImpact.ts      # Command handler — user input flow
├── services/
│   └── ibmiService.ts        # IBM i connection wrapper + SQL/CL queries
├── panels/
│   └── impactPanel.ts        # Webview panel — HTML report generation
└── models/
    └── types.ts              # Shared TypeScript interfaces

Troubleshooting

"Code for IBM i (Code4i) extension is not installed"

Install the halcyontechltd.code-for-ibmi extension from the VS Code Marketplace and connect to an IBM i system.

"Not connected to IBM i"

Open the Code for IBM i panel and establish a connection before running the analysis.

"No columns found for LIB/FILE"

• Confirm the file exists in the specified library
• Confirm it is a physical file (*FILE with attribute PF)
• Confirm your IBM i user has *USE authority to QSYS2.SYSCOLUMNS

Deep Scan fails or returns no programs

• Your IBM i user needs authority to run DSPPGMREF and to create objects in QTEMP
• Large libraries (thousands of programs) may take several minutes
• If DSPPGMREF is not available on your IBM i release, use Quick Scan and review programs manually

Limitations

• Only analyzes physical files (*FILE PF). Logical files and SQL views are shown as dependents, not as input sources.
• SQL routine dependencies are listed as potential because QSYS2.SYSROUTINES does not expose the routine body for cross-referencing. Review them manually.
• Programs compiled against a logical file (rather than directly against the physical) are only found if the logical file itself appears in the Deep Scan results.
• Deep Scan scans the entire specified library. Cross-library program references are not covered.

License

MIT — see LICENSE