Angular.JS利用ng-disabled属性和ng-model实现禁用button效果

<div> 
 <div> 
  <textarea name="" id="" rows="3" class="form-control" ng-model="shyj" placeholder="在此输入审批意见"></textarea> 
 </div> 
 <div> 
  <div> 
   <button class="btn btn-sm btn-block btn-primary" ng-disabled="!shyj" 
    ng-click="agreeClick(SM.YGBH,SM.RQ,shyj);" ng-tap="$navigate.go('/home')"> 
   提交 
   </button> 
  </div> 
 </div> 
</div> 

$scope.agreeClick=function(v_shyg,v_rq,shyj){//审核通过 
 $scope.v_shzt=0; 
 $scope.v_shyg=v_shyg; 
 $scope.v_rq=v_rq; 
 $scope.shyj=shyj; 
 $scope.v_lsh=0; 
 /*if(!$scope.shyj||$scope.shyj==''){ 
  myTip("审核意见不能为空"); 
  return false; 
 }*/ 
 HomeService.agreeClick({YGBH:$scope.YGBH,v_rq:$scope.v_rq,v_shzt:$scope.v_shzt,v_shyg:$scope.v_shyg,v_shyj:$scope.shyj,v_lsh:$scope.v_lsh}).then(function(data){ 
  var info=data.msg; 
  if (info[0].code === "0") {//查询到结果 
  myTip("审核成功"); 
   $navigate.go("/LogList"); 
  }else{ 
   myTip("审核失败:"+info[0].msg); 
  } 
//  console.log("desk: %o", data); 
//  $scope.LogList=data.answers[0]; 
//  $scope.abc=data.answers[0][0].YGBH; 
//  console.log("bb: %o",$scope.abc); 
   }); 
}