---
title: Filter
description: Filter represents a CEL-based expression applied to query or stream results.
source_url:
  html: https://thru.org/docs/api-ref/grpc/messages/thru/common/v1/filter/
  md: https://thru.org/docs/api-ref/grpc/messages/thru/common/v1/filter.md
---

# Filter

Filter represents a CEL-based expression applied to query or stream results.

**Package:** `thru.common.v1`

## Fields

| Field | Type | # | Description |
| - | - | - | - |
| `expression` | `string` | 1 · optional | CEL expression applied server-side. Empty expressions are treated as no-op. |
| `params` | map\<string, [`FilterParamValue`](https://thru.org/docs/api-ref/grpc/messages/thru/common/v1/filter-param-value.md)> | 2 · optional | Named parameter bindings for expression parameterization. |