Issue #20: add _field_caps support

Author: idrissneumann

pkg/quickwit/quickwit.go

@@ -143,7 +143,9 @@ func (ds *QuickwitDatasource) CallResource(ctx context.Context, req *backend.Cal
 	// - empty string for fetching db version
 	// - ?/_mapping for fetching index mapping
 	// - _msearch for executing getTerms queries
-	if req.Path != "" && !strings.Contains(req.Path, "indexes/") && req.Path != "_elastic/_msearch" {
+	// - _field_caps for getting all the aggregeables fields
+	var isFieldCaps = req.Path != "" && strings.Contains(req.Path, "_elastic") && strings.Contains(req.Path, "/_field_caps")
+	if req.Path != "" && !strings.Contains(req.Path, "indexes/") && req.Path != "_elastic/_msearch" && !isFieldCaps {
 		return fmt.Errorf("invalid resource URL: %s", req.Path)
 	}
 

src/datasource.ts

@@ -348,7 +348,7 @@ export class QuickwitDataSource
       datetime: 'date',
       text: 'string',
     };
-    return from(this.getResource('indexes/' + this.index)).pipe(
+    return from(this.getResource('_elastic/' + this.index + '/_field_caps')).pipe(
       map((index_metadata) => {
         const shouldAddField = (field: QuickwitField) => {
           const translated_type = typeMap[field.field_mapping.type];