Aurelia .withMessage验证css

Question

我有以下代码：

JS

                    .if(() => { return this.HasProvidedEitherSku1OrSku2 === false })
                        .isNotEmpty().withMessage(‘at least one sku is required')
                        .hasLengthBetween(0, 50)
                    .endIf()                    
                    .ensure('Sku2', (config) => {config.computedFrom(['Sku1'])})
                    .if(() => { return this.HasProvidedEitherSku1OrSku2 === false })
                        .isNotEmpty().withMessage(‘at least one sku is required’)
                        .hasLengthBetween(0, 50)
                    .endIf();

HTML

        <div class="col-sm-6">
            <div class="form-group">
                <label class="control-label">SKU</label>
                <input disabled.bind="readonly" type="text" class="form-control" value.bind="Sku1">
            </div>
        </div>
        <div class="col-sm-6">
            <div class="form-group">
                <label class="control-label"> SKU</label>
                <input disabled.bind="readonly" type="text" class="form-control" value.bind="Sku2">
            </div>
        </div>

withMessage seens在if语句中包含时会有不同的反应。而不是向has-warning添加“form-group”。它只是补充说：

<p class="help-block **aurelia-validation-message**">at least one sku is required</p>

如何强制执行'has-warning'？或者接近if语句。如果p class =“”则抓住上面的标签并在下面输入。