jq-json-processing

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• LICENSE
• SKILL.md

SKILL.md (first lines)

# jq JSON Processing

Expert knowledge for processing, querying, and transforming JSON data using jq, the lightweight and flexible command-line JSON processor.

## When to Use This Skill

| Use this skill when... | Use yq-yaml-processing instead when... |
|---|---|
| Extracting or filtering fields in JSON input | Working with YAML files (Kubernetes, GH Actions, Helm) |
| Parsing `gh`, `curl`, or `kubectl -o json` responses | Editing YAML in place while preserving comments |
| CI pipelines on minimal images (jq is universally installed) | Converting YAML → JSON before processing |

| Use this skill when... | Use nushell-data-processing instead when... |
|---|---|
| One-off pipeline transforms that fit in a single expression | Multi-step transforms that span JSON, YAML, CSV, and TOML |
| Stdin-piped JSON from another command | Aggregations, group-by, or visual table exploration |

## Core Expertise

**JSON Operations**
- Query and filter JSON with path expressions
- Transform JSON structure and shape
- Combine, merge, and split JSON data
- Validate JSON syntax and structure

**Data Extraction**
- Extract specific fields from JSON objects
- Filter arrays based on conditions
- Navigate nested JSON structures
- Handle null values and missing keys

## Essential Commands

### Basic Querying

```bash
# Pretty-print JSON
jq '.' file.json

# Extract specific field
jq '.fieldName' file.json

# Extract nested field
jq '.user.email' file.json

# Extract array element
jq '.[0]' file.json
jq '.items[2]' file.json
```

### Array Operations

```bash
# Get array length
jq '.items | length' file.json

# Map over array
jq '.items | map(.name)' file.json

# Filter array
jq '.items[] | select(.active == true)' file.json
jq '.users[] | select(.age > 18)' file.json

# Sort array
jq '.items | sort_by(.name)' file.json
jq '.items | sort_by(.date) | reverse' file.json

# Get first/last elements
jq '.items | first' file.json
jq '.items | last' file.json

# Unique values
jq '.tags | unique' file.json
```

### Object Operations

```bash
# Get all keys
jq 'keys' file.json
jq '.config | keys' file.json

# Get all values
jq '.[] | values' file.json

# Select specific fields
jq '{name, email}' file.json
jq '{name: .fullName, id: .userId}' file.json

# Add field
jq '. + {newField: "value"}' file.json

# Delete field
jq 'del(.password)' file.json

# Merge objects
jq '. * {updated: true}' file.json
```

### Filtering and Conditions

```bash
# Select with conditions
jq 'select(.status == "active")' file.json
jq '.[] | select(.price < 100)' file.json

# Multiple conditions (AND)
jq '.[] | select(.active and .verified)' file.json
jq '.[] | select(.age > 18 and .country == "US")' file.json

# Multiple conditions (OR)
jq '.[] | select(.type == "admin" or .type == "moderator")' file.json

# Exists / has field
jq '.[] | select(has("email"))' file.json
jq 'select(.optional != null)' file.json

# Not condition
jq '.[] | select(.status != "deleted")' file.json

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