[{"_id":"6360468045689c3d0c70e53c","name":"Folder1","path":"files/Folder1","parentFolder":"6360468045689c3d0c70e53c"},{"_id":"6360468045689c3d0c70e53f","name":"xxx","path":"files/xxx"},{"_id":"6360468d45689c3d0c70e558","name":"Folder2","path":"files/Folder2","parentFolder":"6360468045689c3d0c70e53c"},{"_id":"6360469445689c3d0c70e55c","name":"Folder3","path":"files/Folder3","parentFolder":"6360468d45689c3d0c70e558"},{"_id":"636a732946b670e689afd454","name":"images","path":"files/images","parentFolder":"6360468045689c3d0c70e53c"},{"_id":"636a735f46b670e689afd46d","name":"images","path":"files/images","parentFolder":"6360468d45689c3d0c70e558"}]

db.collection.aggregate([{$match:{parentFolder:{$exists:true}}},{$graphLookup:{from:"collection",startWith:"$_id",connectFromField:"parentFolder",connectToField:"parentFolder",maxDepth:1,depthField:"depth",as:"TreeResult"}}])