added method to list fields in the index

also added a corresponding http handler

http/fields.go

@@ -0,0 +1,55 @@
+//  Copyright (c) 2014 Couchbase, Inc.
+//  Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file
+//  except in compliance with the License. You may obtain a copy of the License at
+//    http://www.apache.org/licenses/LICENSE-2.0
+//  Unless required by applicable law or agreed to in writing, software distributed under the
+//  License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND,
+//  either express or implied. See the License for the specific language governing permissions
+//  and limitations under the License.
+package http
+
+import (
+	"fmt"
+	"net/http"
+
+	"github.com/gorilla/mux"
+)
+
+type ListFieldsHandler struct {
+	defaultIndexName string
+}
+
+func NewListFieldsHandler(defaultIndexName string) *ListFieldsHandler {
+	return &ListFieldsHandler{
+		defaultIndexName: defaultIndexName,
+	}
+}
+
+func (h *ListFieldsHandler) ServeHTTP(w http.ResponseWriter, req *http.Request) {
+
+	// find the index to operate on
+	indexName := mux.Vars(req)["indexName"]
+	if indexName == "" {
+		indexName = h.defaultIndexName
+	}
+	index := IndexByName(indexName)
+	if index == nil {
+		showError(w, req, fmt.Sprintf("no such index '%s'", indexName), 404)
+		return
+	}
+
+	fields, err := index.Fields()
+	if err != nil {
+		showError(w, req, fmt.Sprintf("error: %v", err), 500)
+		return
+	}
+
+	fieldsResponse := struct {
+		Fields []string `json:"fields"`
+	}{
+		Fields: fields,
+	}
+
+	// encode the response
+	mustEncode(w, fieldsResponse)
+}

index.go

@@ -35,6 +35,8 @@ type Index interface {
 
 	Search(req *SearchRequest) (*SearchResult, error)
 
+	Fields() ([]string, error)
+
 	Dump()
 	DumpDoc(id string) ([]interface{}, error)
 	DumpFields()

index/index.go

@@ -26,6 +26,8 @@ type Index interface {
 
 	Document(id string) (*document.Document, error)
 
+	Fields() ([]string, error)
+
 	Dump()
 	DumpDoc(id string) ([]interface{}, error)
 	DumpFields()

index/upside_down/upside_down.go

@@ -486,6 +486,32 @@ func (udc *UpsideDownCouch) Dump() {
 	}
 }
 
+func (udc *UpsideDownCouch) Fields() ([]string, error) {
+	rv := make([]string, 0)
+	it := udc.store.Iterator([]byte{'f'})
+	defer it.Close()
+	key, val, valid := it.Current()
+	for valid {
+		if !bytes.HasPrefix(key, []byte{'f'}) {
+			break
+		}
+		row, err := ParseFromKeyValue(key, val)
+		if err != nil {
+			return nil, err
+		}
+		if row != nil {
+			fieldRow, ok := row.(*FieldRow)
+			if ok {
+				rv = append(rv, fieldRow.name)
+			}
+		}
+
+		it.Next()
+		key, val, valid = it.Current()
+	}
+	return rv, nil
+}
+
 func (udc *UpsideDownCouch) DumpFields() {
 	it := udc.store.Iterator([]byte{'f'})
 	defer it.Close()

index_impl.go

@@ -164,6 +164,10 @@ func (i *indexImpl) Dump() {
 	i.i.Dump()
 }
 
+func (i *indexImpl) Fields() ([]string, error) {
+	return i.i.Fields()
+}
+
 func (i *indexImpl) DumpFields() {
 	i.i.DumpFields()
 }