CSV fill defaults

csv-fill-defaults · version 1.0.0 · CSV & tables · free, no key needed

Replace empty cells in named CSV columns with exact default strings.

Use when you need to: csv fill defaults · fill empty csv cells with defaults · replace empty csv cells.

Supported

• csv fill defaults
• fill empty csv cells with defaults
• replace empty csv cells
• csv fill empty columns

Not supported

• trim cells before filling
• fill whitespace-only cells
• infer defaults
• fuzzy column matching
• type coercion
• read files
• fetch urls

Behavior

• The first CSV record is the header row.
• defaults own keys must name existing headers exactly; unknown columns are rejected.
• Only cells whose string length is 0 are replaced; whitespace-only cells are left unchanged.
• An empty default string is a no-op and does not increment cells_filled.
• Other columns and non-empty cells are preserved without trimming or type coercion.
• An empty document without a header is rejected when defaults is non-empty; a header-only document yields header-only output.
• The first output header name may not begin with U+FEFF because it is ambiguous with a CSV byte-order mark.

Input

• csv (string, required): max length 256000
• defaults (object, required)

Output

• csv (string, required)
• cells_filled (integer, required): min 0

Limits

• max input bytes: 256000
• max data rows: 5000
• max columns: 256
• max header name bytes: 256
• max default columns: 256
• max output bytes: 256000

Example

Request input:

{
  "csv": "name,city,status\nAda,,\n,London,ok\n",
  "defaults": {
    "name": "Anonymous",
    "city": "Unknown",
    "status": "pending"
  }
}

Response:

{
  "result": {
    "csv": "name,city,status\nAda,Unknown,pending\nAnonymous,London,ok\n",
    "cells_filled": 3
  }
}

How to call it

MCP

Connect https://computefirst.net/mcp (setup), then call execute with:

{
  "id": "csv-fill-defaults",
  "version": "1.0.0",
  "input": {
    "csv": "name,city,status\nAda,,\n,London,ok\n",
    "defaults": {
      "name": "Anonymous",
      "city": "Unknown",
      "status": "pending"
    }
  }
}

HTTP (no key)

curl -X POST https://computefirst.net/v1/tools/csv-fill-defaults/versions/1.0.0/execute \
  -H "Content-Type: application/json" \
  -d '{"csv":"name,city,status\nAda,,\n,London,ok\n","defaults":{"name":"Anonymous","city":"Unknown","status":"pending"}}'

The machine-readable contract is at /v1/tools/csv-fill-defaults/versions/1.0.0.

CLI

node cli.mjs run csv-fill-defaults 1.0.0 --input input.json --base-url https://computefirst.net

Get the client at /clients/cli/.

Related tools

• CSV filter empty: Keep or drop CSV rows whose named column is the empty string.
• CSV merge columns: Join named CSV columns with an exact separator into one column.
• CSV replace exact: Replace CSV data cells whose entire value equals an exact find string.
• CSV concat: Concatenate CSV documents that share identical headers, preserving document and row order.
• CSV dedupe: Remove duplicate CSV data rows while preserving the first occurrence.
• CSV drop columns: Drop named CSV columns and keep the remaining columns in original header order.