> ## Documentation Index
> Fetch the complete documentation index at: https://docs.appsignal.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Add Function Parameters

export const Compatibility = ({versions = [], label = "Available in"}) => {
  if (!Array.isArray(versions) || versions.length === 0) {
    return null;
  }
  const defaultPillStyle = {
    borderColor: "#d4d4d8",
    background: "#f4f4f5",
    color: "#3f3f46"
  };
  const pillStyles = {
    "AppSignal for Elixir": {
      background: "#f3e8ff",
      borderColor: "#d8b4fe",
      color: "#6b21a8"
    },
    "AppSignal for Front-end": {
      background: "#fef9c3",
      borderColor: "#fde047",
      color: "#854d0e"
    },
    "AppSignal for Go": {
      background: "#ccfbf1",
      borderColor: "#5eead4",
      color: "#115e59"
    },
    "AppSignal for JavaScript": {
      background: "#fef9c3",
      borderColor: "#fde047",
      color: "#854d0e"
    },
    "AppSignal for Node.js": {
      background: "#dcfce7",
      borderColor: "#86efac",
      color: "#166534"
    },
    "AppSignal for Python": {
      background: "#dbeafe",
      borderColor: "#93c5fd",
      color: "#1e40af"
    },
    "AppSignal for Ruby": {
      background: "#fee2e2",
      borderColor: "#fca5a5",
      color: "#991b1b"
    },
    "AppSignal for Rust": {
      background: "#ffedd5",
      borderColor: "#fdba74",
      color: "#9a3412"
    }
  };
  const getPillStyle = name => ({
    ...defaultPillStyle,
    ...pillStyles[name] || ({})
  });
  return <div className="not-prose my-4 rounded-lg border border-zinc-200 bg-zinc-50 px-4 py-3 text-sm dark:border-white/10 dark:bg-white/5">
      <div className="flex flex-wrap items-center gap-x-2 gap-y-1">
        <span className="font-semibold text-zinc-700 dark:text-zinc-200">
          {label}:
        </span>
        {versions.map((v, i) => <span key={`${v.name}-${v.version}-${i}`} className="inline-flex items-center gap-1 rounded-full border px-2 py-0.5 text-xs font-medium" style={getPillStyle(v.name)}>
            <span>{v.name}</span>
            <span className="opacity-70">
              {v.version}
              {v.exact ? "" : "+"}
            </span>
          </span>)}
      </div>
    </div>;
};

<Compatibility versions={[{ name: "AppSignal for PHP", version: "0.5.0" }]} />

<Compatibility versions={[{ name: "AppSignal Collector", version: "0.6.0" }]} />

PHP and the languages supported through our OpenTelemetry beta can set function parameters.
Function parameters are designated for background jobs and scripts, not for storing parameters for each function call in a trace.

<Warning>
  🔐 Do not send <strong>Personal Identifiable Information (PII)</strong> to AppSignal. Filter PII (e.g., names, emails) and use an ID, hash, or pseudonymized identifier instead. <br /> <br /> Use [Link Templates](https://docs.appsignal.com/application/link-templates) to link them back in your app.
</Warning>

For security and privacy we recommend [filtering function parameters](/guides/filter-data/filter-function-parameters) before sending them to our servers.

See the table below for a list of accepted root values per language. Each nested object can contain values that result in valid JSON (strings, integers, floats, booleans, nulls, etc.).

| Language | Accepted root values   |
| -------- | ---------------------- |
| Go       | JSON serialized string |
| Java     | JSON serialized string |
| PHP      | Arrays, Objects        |

The below code sample shows how to set custom request parameters:

<CodeGroup>
  ```go Go theme={null}
  // Additional setup is required to first fetch or create a new span
  import (
  	"encoding/json"

  	"go.opentelemetry.io/otel/attribute"
  	"go.opentelemetry.io/otel/trace"
  )

  params := map[string]interface{}{
  	"param1": "value1",
  	"param2": "value2",
  	"nested": map[string]interface{}{
  		"param3": "value3",
  		"param4": "value4",
  	},
  }
  json, _ := json.Marshal(params)
  span.SetAttributes(attribute.String("appsignal.function.parameters", string(json)))
  ```

  ```java Java theme={null}
  // Additional setup is required to first fetch or create a new span
  import io.opentelemetry.api.trace.Span;
  // We're using the Jackson JSON library
  // You may need to add it to your project as a dependency
  import com.fasterxml.jackson.databind.ObjectMapper;
  import java.util.HashMap;
  import java.util.Map;

  Map<String, Object> params = new HashMap<>();
  params.put("param1", "value1");
  params.put("param2", "value2");

  Map<String, String> nested = new HashMap<>();
  nested.put("param3", "value3");
  nested.put("param4", "value4");
  params.put("nested", nested);

  try {
      ObjectMapper mapper = new ObjectMapper();
      String jsonString = mapper.writeValueAsString(params);

      Span span = Span.current();
      span.setAttribute("appsignal.function.parameters", jsonString);
  } catch (Exception e) {
      // Add error handling here
  }
  ```

  ```php PHP theme={null}
  <?php
  use Appsignal\Appsignal;

  $params = [
      'param1' => 'value1',
      'param2' => 'value2',
      'nested' => [
          'param3' => 'value3',
          'param4' => 'value4',
      ],
  ];

  Appsignal::setFunctionParams($params);
  ```
</CodeGroup>

For certain languages, additional setup is required.
Please follow the instructions for these languages:

* [Go](/go/custom-instrumentation)
* [Java](/java/custom-instrumentation)

## Limitations

If the application sets function parameters multiple times, the latest set value is leading.