Fix Missing ns()

Check for Missing `ns()` in Modules

Validate that all module input/output IDs are properly namespaced.

Why Namespacing Matters

In Shiny modules, all input and output IDs must be namespaced using the ns() function. This prevents ID conflicts when the same module is used multiple times in an app.

Correct vs Incorrect

✅ Correct

mod_analytics_ui <- function(id) {
  ns <- NS(id)
  tagList(
    selectInput(
      ns("type_filter"),
      label = NULL,
      choices = c("All", "None")
    )
  )
}

❌ Incorrect

mod_analytics_ui <- function(id) {
  ns <- NS(id)
  tagList(
    selectInput(
      "type_filter",  # Missing ns()!
      label = NULL,
      choices = c("All", "None")
    )
  )
}

What to Check

In Module UI Functions

All input IDs: textInput(), selectInput(), actionButton(), etc.
All output IDs: plotOutput(), tableOutput(), uiOutput(), etc.
All input control IDs used in ns() calls

In Module Server Functions

JavaScript handler IDs that reference the module namespace
observeEvent(input$...) references
output$... definitions
renderUI() generated element IDs

Places to Look

Any file starting with mod_ in the R/ directory
Both UI and server functions within modules

How Claude Checks

Locate all IDs in module files (files starting with mod_)
- Search for common patterns: Input(), Output(), input/output IDs
Verify namespacing by checking each ID is wrapped in ns()
- Exception: Only the first NS(id) definition doesn’t need wrapping
Report findings
- If all IDs are properly namespaced: ✅ All good
- If missing IDs found: ❌ List them and ask for permission to fix
Fix if approved
- Wrap missing IDs in ns()
- Preserve code structure and formatting

Common Mistakes

Mistake	Fix
`selectInput("myid", ...)`	`selectInput(ns("myid"), ...)`
`plotOutput("plot")`	`plotOutput(ns("plot"))`
`observeEvent(input$button)`	`observeEvent(input$submit, ...)` with ID properly namespaced
`uiOutput("dynamic")`	`uiOutput(ns("dynamic"))`

When to Run

After creating or modifying module UI functions
Before running devtools::check()
When adding new inputs/outputs to modules
Before deploying to production

Example Workflow

User: Check my modules for missing ns()

Claude:
1. Scans all mod_*.R files
2. Identifies 3 missing ns() wrappings
3. Shows the issues with line numbers
4. Asks: "Should I fix these?"

User: Yes, fix them

Claude:
- Updates the files
- Runs the check again to verify
- Confirms: "All fixed! ✅"

Notes

This check is for UI and reactive server code, not data processing functions
Only module files (mod_*.R) need this check
Regular functions (fct_*.R, utils_*.R) don’t need namespace wrapping
Module server functions are called with the module ID, which handles the namespacing

Check for Missing ns() in Modules