# Querying JSON

> Extracts specific fields from JSON files efficiently using jq instead of reading entire files, saving 80-95% context. Use this skill when querying JSON files, filtering/transforming data, or getting specific field(s) from large JSON files

- Skill: `tomevault-io/querying-json` (Agent Skill, multi-file: 2 files)
- Install (CLI): `npx skillmds@latest add tomevault-io/querying-json`
- Raw SKILL.md: https://api.skillmd.com/api/skills/tomevault-io/querying-json/raw
- Safety review: pending (external: skill-scanner PASS, skillspector PASS)
- Works with: Claude Code, Claude.ai, OpenAI Codex
- Category: Coding & Dev Tools
- Author: tomevault-io (https://skillmd.com/u/tomevault-io)
- Updated: 2026-09-17
- Page: https://skillmd.com/skills/tomevault-io/querying-json

---


# jq: JSON Data Extraction Tool

**Always invoke jq skill to extract JSON fields - do not execute bash commands directly.**

Use jq to extract specific fields from JSON files without loading entire file contents into context.

## When to Use jq vs Read

**Use jq when:**
- Need specific field(s) from structured data file
- File is large (>50 lines) and only need subset
- Querying nested structures
- Filtering/transforming data
- **Saves 80-95% context** vs reading entire file

**Just use Read when:**
- File is small (<50 lines)
- Need to understand overall structure
- Making edits (need full context anyway)

## Common File Types

JSON files where jq excels:
- package.json, tsconfig.json
- Lock files (package-lock.json, yarn.lock in JSON format)
- API responses
- Configuration files

## Default Strategy

**Invoke jq skill** for extracting specific fields from JSON files efficiently. Use instead of reading entire files to save 80-95% context.

Common workflow: fd skill → jq skill → other skills (fzf, sd, bat) for extraction and transformation.

## Quick Examples

```bash
# Get version from package.json
jq -r .version package.json

# Get nested dependency version
jq -r '.dependencies.react' package.json

# List all dependencies
jq -r '.dependencies | keys[]' package.json
```

## Pipeline Combinations
- **jq | fzf**: Interactive selection from JSON data
- **jq | sd**: Transform JSON to other formats
- **jq | bat**: View extracted JSON with syntax highlighting

## Skill Combinations

### For Discovery Phase
- **fd → jq**: Find JSON config files and extract specific fields
- **ripgrep → jq**: Find JSON usage patterns and extract values
- **extracting-code-structure → jq**: Understand API structures before extraction

### For Analysis Phase
- **jq → fzf**: Interactive selection from structured data
- **jq → bat**: View extracted data with syntax highlighting
- **jq → tokei**: Extract statistics from JSON output

### For Refactoring Phase
- **jq → sd**: Transform JSON data to other formats
- **jq → yq**: Convert JSON to YAML for different tools
- **jq → xargs**: Use extracted values as command arguments

### Multi-Skill Workflows
- **jq → yq → sd → bat**: JSON to YAML transformation with preview
- **jq → fzf → xargs**: Interactive selection and execution based on JSON data
- **fd → jq → ripgrep**: Find config files, extract values, search usage

### Common Integration Examples
```bash
# Extract and select dependencies
jq -r '.dependencies | keys[]' package.json | fzf --multi | xargs npm info

# Get and filter package versions
jq -r '.devDependencies | to_entries[] | "\(.key)@\(.value)"' package.json | fzf
```

### Note: Choosing Between jq and yq
- **JSON files** (package.json, tsconfig.json): Use `jq`
- **YAML files** (docker-compose.yml, GitHub Actions): Use `yq`

## Detailed Reference

For comprehensive jq patterns, syntax, and examples, load [jq guide](./reference/jq-guide.md) when needing:
- Array manipulation and filtering
- Complex nested data extraction
- Data transformation patterns
- Real-world workflow examples
- Error handling and edge cases
- Core patterns (80% of use cases)
- Real-world workflows
- Advanced patterns
- Pipe composition
- Error handling
- Integration with other tools

---
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<!-- tomevault:4.0:skill_md:2026-04-12 -->