如何在View中获取ViewBag内存储的Dictionary数据

我无法弄清如何从存储了Dictionary的ViewBag中获取数据，以下是后台相关代码：

if (dataSet.Tables[2].Rows.Count > 1) {
    evalMitModel = new EvaluationMitigationApproverModel();
    evalMitModel.MitigationType = new List<string>();
    evalMitModel.MitigationDescription = new List<string>();
    evalMitModel.PersonResponsible = new List<string>();
    evalMitModel.TargetDate = new List<string>();
    string temp = dataSet.Tables[2].Rows[0]["id_hazard_trans"].ToString();
    int counter = 1;
    for (int index = 0; index < dataSet.Tables[2].Rows.Count; index++) {
        if (temp == dataSet.Tables[2].Rows[index]["id_hazard_trans"].ToString()) {
            if (evalMitModel.HazardTransactionId == null) {
                evalMitModel.HazardTransactionId = dataSet.Tables[2].Rows[index]["id_hazard_trans"].ToString();
                evalMitModel.HazardId = dataSet.Tables[2].Rows[index]["id_hazard"].ToString();
                evalMitModel.ImpactId = dataSet.Tables[2].Rows[index]["impact_id"].ToString();
                evalMitModel.LikeId = dataSet.Tables[2].Rows[index]["like_id"].ToString();
                evalMitModel.Scale = dataSet.Tables[2].Rows[index]["Scale"].ToString();
                evalMitModel.ApproverStatus = dataSet.Tables[2].Rows[index]["apprv_status"].ToString();
                evalMitModel.ApproverComment = dataSet.Tables[2].Rows[index]["apprv_comment"].ToString();
            }
            evalMitModel.MitigationType.Add(dataSet.Tables[2].Rows[index]["cnt_type"].ToString());
            evalMitModel.MitigationDescription.Add(dataSet.Tables[2].Rows[index]["cnt_desc"].ToString());
            evalMitModel.PersonResponsible.Add(dataSet.Tables[2].Rows[index]["pers_resp"].ToString());
        }
        else {
            evalMitHashMap.Add(counter++, evalMitModel);
            evalMitModel = new EvaluationMitigationApproverModel();
            evalMitModel.MitigationType = new List<string>();
            evalMitModel.MitigationDescription = new List<string>();
            evalMitModel.PersonResponsible = new List<string>();
            temp = dataSet.Tables[2].Rows[index]["id_hazard_trans"].ToString();
            index--;
            //evalMitModel.HazardTransactionId = null;
        }
    }
    evalMitHashMap.Add(counter, evalMitModel);
    ViewBag.EvaluationMitigationHashMap = evalMitHashMap;
}

我尝试在视图中用Razor语法获取数据，但无法正确遍历：

@if (ViewBag.EvaluationMitigationHashMap != null) { foreach (var data in ViewBag.EvaluationMitigationHashMap) {

解决方法 #

ViewBag是动态类型，直接遍历会因类型不确定出现问题，需先强转为对应的Dictionary类型，再遍历键值对：

1. 强转匹配类型：后台的evalMitHashMap是Dictionary<int, EvaluationMitigationApproverModel>类型（键为int类型的counter，值为自定义模型），视图中先将ViewBag内容强转为此类型。
2. 遍历键值对：每个遍历项是KeyValuePair<int, EvaluationMitigationApproverModel>，通过Key获取序号，通过Value访问模型的所有属性，List类型属性需嵌套遍历。

修正后的视图代码示例：

@if (ViewBag.EvaluationMitigationHashMap != null)
{
    // 强转为对应的Dictionary类型
    var mitigationDataMap = ViewBag.EvaluationMitigationHashMap as Dictionary<int, EvaluationMitigationApproverModel>;
    if (mitigationDataMap != null)
    {
        foreach (var kvp in mitigationDataMap)
        {
            // 访问后台的counter序号
            <div>序号: @kvp.Key</div>
            
            // 访问模型基础属性
            <div>危险事务ID: @kvp.Value.HazardTransactionId</div>
            <div>审批状态: @kvp.Value.ApproverStatus</div>
            <div>审批意见: @kvp.Value.ApproverComment</div>
            
            // 遍历List类型的缓解措施类型
            <div>
                <h5>缓解措施类型:</h5>
                @foreach (var type in kvp.Value.MitigationType)
                {
                    <span>@type </span>
                }
            </div>
            
            // 遍历List类型的缓解措施描述
            <div>
                <h5>缓解措施描述:</h5>
                @foreach (var desc in kvp.Value.MitigationDescription)
                {
                    <p>@desc</p>
                }
            </div>
        }
    }
}

额外提示 #

• 建议在后台显式声明evalMitHashMap的类型，避免隐式类型带来的不确定性：

  var evalMitHashMap = new Dictionary<int, EvaluationMitigationApproverModel>();
  

• 强转时必须保证类型完全匹配，否则会返回null，因此要添加null判断。

内容的提问来源于stack exchange，提问作者Musaib Bilal