expand QTree method

expandTree.vue

    expandTree: function (absolutePath) {
      // get parts for the path
      let parts = absolutePath.split(path.sep)
      let path2 = ''
      let lastNodeKey

      // iterate through the path parts.
      // This code will get the node. If the node is not found,
      // it forces lazy-load by programmatically expanding
      // the parent node.
      for (let index = 0; index < parts.length; ++index) {
        if (parts[index].length === 0) {
          continue
        }
        if (index === 0) {
          path2 += parts[index] + path.sep
        }
        else {
          if (path2[path2.length - 1] !== path.sep) {
            path2 += path.sep
          }
          path2 += parts[index]
        }
        if (index > -1) {
          if ('folders' in this.$refs) {
            const key = this.$refs.folders.getNodeByKey(path2)
            // if we get key, then this folder has already been loaded
            if (key) {
              lastNodeKey = key
            }
            // handle folder not expanded
            if (!this.$refs.folders.isExpanded(lastNodeKey.nodeKey)) {
              this.$refs.folders.setExpanded(lastNodeKey.nodeKey, true)
              if (path2 === absolutePath) {
                this.selected = absolutePath
              }
              else {
                this.$nextTick(() => {
                  this.$root.$emit('expand-tree', absolutePath)
                })
              }
            }
          }
        }
      }
    }