The `neural_query_enricher` search request processor is designed to set a default machine learning (ML) model ID at the index or field level for [neural search]({{site.url}}{{site.baseurl}}/search-plugins/neural-search/) queries. To learn more about ML models, see [Using custom models within OpenSearch]({{site.url}}{{site.baseurl}}/ml-commons-plugin/ml-framework/).
The following table lists all available request fields.
Field | Data type | Description
:--- | :--- | :---
`default_model_id` | String | The model ID of the default model for an index. Optional. You must specify at least one `default_model_id` or `neural_field_default_id`. If both are provided, `neural_field_default_id` takes precedence.
`neural_field_default_id` | Object | A map of key-value pairs representing document field names and their associated default model IDs. Optional. You must specify at least one `default_model_id` or `neural_field_default_id`. If both are provided, `neural_field_default_id` takes precedence.
`tag` | String | The processor's identifier. Optional.
`description` | String | A description of the processor. Optional.
## Example
The following example request creates a search pipeline with a `neural_query_enricher` search request processor. The processor sets a default model ID at the index level and provides different default model IDs for two specific fields in the index:
```json
PUT /_search/pipeline/default_model_pipeline
{
"request_processors": [
{
"neural_query_enricher" : {
"tag": "tag1",
"description": "Sets the default model ID at index and field levels",