Add shared_docs param (#4548)

A `shared_docs` param is added to the GET `/sharings/doctype` route, in
order for the client to tell whether or not the `shared_docs`
relationships is required in the response, as this can be costful in
case of sharings with a lot of documents.

Author: paultranvan

docs/sharing.md

@@ -433,11 +433,15 @@ Content-Type: application/vnd.api+json
 Get information about all the sharings that have a rule for the given doctype.
 This includes the content of the rules, the members, as well as the already
 shared documents for this sharing.
+A `shared_docs` query parameter is supported to control whether or not the
+shared docs should be included in the response. Default is true.
+This can be costful in case of large sharings, so it can be a good idea to set
+it to false for performances. 
 
 #### Request
 
 ```http
-GET /sharings/doctype/io.cozy.files HTTP/1.1
+GET /sharings/doctype/io.cozy.files?shared_docs=true HTTP/1.1
 Host: alice.example.net
 Accept: application/vnd.api+json
 ```

web/sharings/sharings.go

@@ -198,7 +198,10 @@ func CountNewShortcuts(c echo.Context) error {
 func GetSharingsInfoByDocType(c echo.Context) error {
 	inst := middlewares.GetInstance(c)
 	docType := c.Param("doctype")
-
+	withSharedDocs, err := strconv.ParseBool(c.QueryParam("shared_docs"))
+	if err != nil {
+		withSharedDocs = true
+	}
 	sharings, err := sharing.GetSharingsByDocType(inst, docType)
 	if err != nil {
 		inst.Logger().WithNamespace("sharing").Errorf("GetSharingsByDocType error: %s", err)
@@ -214,10 +217,14 @@ func GetSharingsInfoByDocType(c echo.Context) error {
 	for sID := range sharings {
 		sharingIDs = append(sharingIDs, sID)
 	}
-	sDocs, err := sharing.GetSharedDocsBySharingIDs(inst, sharingIDs)
-	if err != nil {
-		inst.Logger().WithNamespace("sharing").Errorf("GetSharedDocsBySharingIDs error: %s", err)
-		return wrapErrors(err)
+
+	var sDocs map[string][]couchdb.DocReference
+	if withSharedDocs {
+		sDocs, err = sharing.GetSharedDocsBySharingIDs(inst, sharingIDs)
+		if err != nil {
+			inst.Logger().WithNamespace("sharing").Errorf("GetSharedDocsBySharingIDs error: %s", err)
+			return wrapErrors(err)
+		}
 	}
 
 	res := make([]*sharing.APISharing, 0, len(sharings))