Validator.RenderControl返回空字符串

Question

我已经面对了下面的问题，并与之斗争了近两天。我有以下代码。

        protected override void Render(HtmlTextWriter writer)
    {
        string controlOutput;
        string validatorOutput;
        string allOutput;
        StringWriter controlStringWriter = new StringWriter();
        HtmlTextWriter controlHtmlWriter = new HtmlTextWriter(controlStringWriter);

        StringWriter validatorsStringWriter = new StringWriter();
        HtmlTextWriter validatorsHtmlWriter = new HtmlTextWriter(validatorsStringWriter);

        base.Render(controlHtmlWriter);
        controlOutput = controlStringWriter.ToString();

        this.renderValidators(validatorsHtmlWriter);
        validatorOutput = validatorsStringWriter.ToString();

        allOutput = String.Format("{0} {1}", controlOutput, validatorOutput);
        writer.Write(allOutput);
    }

renderValidators函数为：

  private void renderValidators(HtmlTextWriter writer)
        {
            foreach (BaseValidator validator in this.ValidatorsCollection)
            {
                validator.RenderControl(writer);
            }
        }

Render函数返回空字符串。集合中的Validator的Visible属性设置为true。

我在OnInit函数中添加了验证器。在第一次渲染validator.RenderControl(编写器)时，返回一个空字符串，回发之后，它开始返回html输入...

也许有人遇到过这样的问题？

Answer 1

据我所知，在呈现验证器之前，您需要检查控件是否已添加到页面中。

        Page page = Page;
        if (page == null || page.Request == null) {
            return false;
        }

在MSDN中可以找到一个非常有用的示例