Field Capabilities API

A FieldCapabilitiesRequest contains a list of fields to get capabilities for, plus an optional list of target indices. If no indices are provided, the request runs on all indices.

Note that fields parameter supports wildcard notation. For example, providing text_* will cause all fields that match the expression to be returned.

FieldCapabilitiesRequest request = new FieldCapabilitiesRequest()
    .fields("user")
    .indices("posts", "authors", "contributors");

request.indicesOptions(IndicesOptions.lenientExpandOpen()); 

The fieldCaps method executes the request synchronously:

FieldCapabilitiesResponse response = client.fieldCaps(request, requestOptions);

The fieldCapsAsync method executes the request asynchronously, calling the provided ActionListener when the response is ready:

client.fieldCapsAsync(request, RequestOptions.DEFAULT, listener); 

The asynchronous method does not block and returns immediately. Once the request completes, the ActionListener is called back using the onResponse method if the execution successfully completed or using the onFailure method if it failed.

A typical listener for FieldCapabilitiesResponse is constructed as follows:

ActionListener<FieldCapabilitiesResponse> listener = new ActionListener<FieldCapabilitiesResponse>() {
    @Override
    public void onResponse(FieldCapabilitiesResponse response) {
        
    }

    @Override
    public void onFailure(Exception e) {
        
    }
};

For each requested field, the returned FieldCapabilitiesResponse contains its type and whether or not it can be searched or aggregated on. The response also gives information about how each index contributes to the field’s capabilities.

Map<String, FieldCapabilities> userResponse = response.getField("user");  
FieldCapabilities textCapabilities = userResponse.get("keyword");

boolean isSearchable = textCapabilities.isSearchable();
boolean isAggregatable = textCapabilities.isAggregatable();

String[] indices = textCapabilities.indices(); 
String[] nonSearchableIndices = textCapabilities.nonSearchableIndices(); 
String[] nonAggregatableIndices = textCapabilities.nonAggregatableIndices();