# log

Outputs a message to the Logs section of the Developer Console. Useful for debugging, tracking script execution, and monitoring variable values.

```liquid
{% log "Hello world!" %}
{% log order.name %}
{% log "Order total: " | append: order.total_price %}
```

#### Syntax

```liquid
{% log value %}
{% log value | filter %}
{% log "string" | append: variable %}
```

#### Parameters

| Parameter | Required | Description                                                   |
| --------- | -------- | ------------------------------------------------------------- |
| `value`   | Yes      | Any value to log - string, number, object, array, or variable |

#### Output Formatting

The log tag automatically formats output based on the value type:

| Value Type  | Output                          |
| ----------- | ------------------------------- |
| String      | Displayed as-is                 |
| Number      | Displayed as-is                 |
| Object      | JSON-formatted with indentation |
| Array       | JSON-formatted with indentation |
| `null`      | Displayed as "null"             |
| `undefined` | Displayed as "undefined"        |

#### Examples

**Log a simple message:**

```liquid
{% log "Script started" %}
```

**Log a variable:**

```liquid
{% log order %}
{% log customer.email %}
{% log line_items %}
```

**Log with appended values:**

```liquid
{% log "Processing order: " | append: order.name %}
{% log "Customer email: " | append: customer.email %}
{% log "Total items: " | append: order.line_items.size %}
```

**Log calculation results:**

```liquid
{% assign discount = order.total_price | times: 0.1 %}
{% log "Discount amount: " | append: discount %}
```

**Debug conditional logic:**

```liquid
{% if customer.orders_count > 10 %}
  {% log "VIP customer detected" %}
  {% assign is_vip = true %}
{% else %}
  {% log "Regular customer" %}
  {% assign is_vip = false %}
{% endif %}
```

**Log loop progress:**

```liquid
{% for item in order.line_items %}
  {% log "Processing item: " | append: item.title %}

  {% comment %} Process item... {% endcomment %}

  {% log "Item " | append: forloop.index | append: " of " | append: forloop.length | append: " complete" %}
{% endfor %}
```

**Log object properties:**

```liquid
{% log "Order ID: " | append: order.id %}
{% log "Order name: " | append: order.name %}
{% log "Created at: " | append: order.created_at %}
{% log "Financial status: " | append: order.financial_status %}
```

**Log entire objects for debugging:**

```liquid
{% comment %} Log full order object {% endcomment %}
{% log order %}

{% comment %} Log API response {% endcomment %}
{% http url: api_endpoint, method: "GET" as response %}
{% log response %}

{% comment %} Log GraphQL result {% endcomment %}
{% graphql query: my_query, variables: vars as result %}
{% log result %}
```

**Log array contents:**

```liquid
{% assign tags = product.tags | split: ", " %}
{% log "Product tags:" %}
{% log tags %}
```

**Track script execution flow:**

```liquid
{% log "=== Starting inventory sync ===" %}

{% log "Step 1: Fetching products..." %}
{% comment %} ... fetch logic ... {% endcomment %}

{% log "Step 2: Processing updates..." %}
{% comment %} ... update logic ... {% endcomment %}

{% log "Step 3: Sending notifications..." %}
{% comment %} ... notification logic ... {% endcomment %}

{% log "=== Inventory sync complete ===" %}
```

**Log with JSON filter for complex objects:**

```liquid
{% json payload %}
  {
    "order_id": {{ order.id }},
    "items": {{ order.line_items | map: "sku" | json }}
  }
{% endjson %}

{% log "Payload created:" %}
{% log payload %}
```

**Conditional logging:**

```liquid
{% if response.status != 200 %}
  {% log "API Error - Status: " | append: response.status %}
  {% log "Error body:" %}
  {% log response.body %}
{% endif %}
```

#### Notes

* Logs appear in the Logs section of the Developer Console
* Objects and arrays are automatically JSON-formatted with 2-space indentation
* Maximum log length is 20,000 characters - longer logs are truncated
* Supports Liquid filters for formatting (e.g., `| append:`, `| upcase`, `| date:`)
* No credit cost for logging
* Use logs liberally during development, consider reducing in production for cleaner output