added ?fields query parameter support to limit the returned api fields

apis/base.go

@@ -14,6 +14,7 @@ import (
 	"github.com/labstack/echo/v5"
 	"github.com/labstack/echo/v5/middleware"
 	"github.com/pocketbase/pocketbase/core"
+	"github.com/pocketbase/pocketbase/tools/rest"
 	"github.com/pocketbase/pocketbase/ui"
 	"github.com/spf13/cast"
 )
@@ -25,6 +26,9 @@ const trailedAdminPath = "/_/"
 func InitApi(app core.App) (*echo.Echo, error) {
 	e := echo.New()
 	e.Debug = app.IsDebug()
+	e.JSONSerializer = &rest.Serializer{
+		FieldsParam: "fields",
+	}
 
 	// configure a custom router
 	e.ResetRouterCreator(func(ec *echo.Echo) echo.Router {

apis/record_helpers.go

@@ -121,7 +121,9 @@ func EnrichRecords(c echo.Context, dao *daos.Dao, records []*models.Record, defa
 	}
 
 	expands := defaultExpands
-	expands = append(expands, strings.Split(c.QueryParam(expandQueryParam), ",")...)
+	if param := c.QueryParam(expandQueryParam); param != "" {
+		expands = append(expands, strings.Split(param, ",")...)
+	}
 	if len(expands) == 0 {
 		return nil // nothing to expand
 	}