Params - Liquid Tag Reference

The params simple tag reads URL query string or form post parameters from the current request. Use it to access user-submitted values and drive dynamic template behavior.

:::note This tag works only inside a Liquid controller template (at controllers/<controller>/<action>.liquid), typically in the before block. It is a silent no-op outside a controller. :::

When params runs

Use params in the before block to set values for the rest of the request:

```liquid

{% before %} {% params product_id: current_request.params.product_id %} {% params quantity: current_request.params.qty | default: 1 %} {% endbefore %} ```

The tag merges what you pass into the request’s own parameters, so the values are read back as current_request.params.product_id and current_request.params.quantity. There is no bare params object: to bind a name you can use directly in the template, use {% variables %} or {% assign %}.

Syntax

```liquid

{% params variable_name: source_value %} ```

Property	Value
Tag Name	params
Type	Simple tag
Source	StoreConnect
Use in phase	before (primarily)

Parameters

Parameter	Description
variable_name	The key to set on the request parameters. Read back as current_request.params.variable_name
source_value	The value to set, usually derived from current_request.params.<key>
Filters optional	Use Liquid filters like default, plus: 0, and strip to transform the value

What’s available in params

• current_request.params — all query string and form POST parameters as a Map
• Liquid filters — default, plus: 0 (numeric coercion), strip, downcase
• Assignment context — values can be simple scalars or filtered/transformed values

A key that was never sent reads as blank rather than raising, so you can test for it directly.

Common tasks with params

1. Extract and provide a default value

```liquid

{% before %} {% assign product_id = current_request.params.id %} {% assign quantity = current_request.params.qty | default: 1 %}

{% if product_id == blank %} {% respond body: ‘{“error”: “product_id required”}’, status: 400, layout: false %} {% endif %}

{% params product_id: product_id, quantity: quantity %} {% endbefore %} ```

2. Extract and transform parameters

```liquid

{% before %} {% assign email = current_request.params.email | strip | downcase %} {% assign discount_code = current_request.params.code | upcase %}

{% action “promotion.apply”, code: discount_code %}

{% params email: email, discount_code: discount_code %} {% endbefore %} ```

3. Extract multiple parameters for cart operations

```liquid

{% before %} {% assign product_id = current_request.params.product_id %} {% assign quantity = current_request.params.qty | default: 1 | plus: 0 %} {% assign price_override = current_request.params.override_price %}

{% action “cart.add”, product_identifier: product_id, quantity: quantity, price: price_override %}

{% params product_id: product_id, quantity: quantity, price_override: price_override %} {% endbefore %} ```

Key behaviors

• Merged into the request — the value is read back as current_request.params.variable_name, from the end of this phase onward
• Filters apply during extraction — default: 1 provides a fallback if the parameter is missing
• Validation recommended — always check if required parameters are blank before using them
• Multiple param tags allowed — extract as many parameters as needed in sequence
• No automatic type coercion — a parameter arrives as a string; coerce it to a number with plus: 0

Best practices

Always validate required parameters

```liquid

{% before %} {% assign order_id = current_request.params.id %}

{% if order_id == blank %} {% redirect to: current_store.orders_path, alert: “Order ID is required” %} {% endif %}

{% params order_id: order_id %} {% endbefore %} ```

Provide sensible defaults

```liquid

{% before %} {% assign page = current_request.params.page | default: 1 | plus: 0 %} {% assign limit = current_request.params.limit | default: 20 | plus: 0 %}

{% if limit > 100 %} {% assign limit = 100 %} {% endif %}

{% params page: page, limit: limit %} {% endbefore %} ```

Use params with actions

```liquid

{% before %} {% assign cart_id = current_request.params.cart %}

{% if cart_id != blank %} {% action “cart.select”, cart_identifier: cart_id %} {% endif %}

{% params cart_id: cart_id %} {% endbefore %} ```

Relationship to variables

• {% params %} — merges values into the request parameters, read back as current_request.params.<name>
• {% variables %} — binds a name directly in the page template, used as <name>
• {% assign %} — an ordinary Liquid local, and the only one of the three available inside the block that sets it
• Difference — params are request input carried forward; variables are rendering data

Related tags

• {% variables %} — declare rendering variables after params are validated
• {% action %} — execute cart/commerce operations using param values
• {% before %} — the phase where params extraction typically happens