MapDataSource

layer id of the specific layer, the specific layer may be a layer or a sublayer

if the specific layer is sublayer, should passed in id of the sublayer's layer.

For example, we have a map which has a map service layer A and we want to get the data source with feature layer B (B is a sublayer of the map service layer), we should call mapDataSource.getDataSourceByLayer(idOfLayerB, idOfLayerA).

The reason why need to pass in layerOfSubLayerId is that: Id of JSAPI layer is unique in its map and id of JSAPI sublayer is unique in its layer. However, id of sublayer is not unique in map. In the case that want to use the method to get layer data source matching a JSAPI sublayer, need to check sublayer id and its layer id to determine a specific node in the data source tree.

For example, we have a JSAPI map with the following structure:

• map
• 1 group layer (id is l1)
  • 1.1 map service layer (id is l2)
    • 1.1.1 sub layer (id is 0)
    • 1.1.2 sub layer (id is 1)
  • 1.2 map service layer (id is l3)
    • 1.2.1 sub layer (id is 0)

1. Assume we want to find sublayer 1.2.1, if only pass in the sublayer id (0), will find two layer 1.1.1 and 1.2.1. To determine unique sublayer 1.2.1, need to pass in the sublayer id (0) and its layer id (l3).
2. Assume we want to find layer 1.2, only need to pass in the layer id (l3).