added placeholder attribute to input tag helper

framework/src/Volo.Abp.AspNetCore.Mvc.UI.Bootstrap/TagHelpers/Form/AbpInputTagHelperService.cs

@@ -125,6 +125,7 @@ namespace Volo.Abp.AspNetCore.Mvc.UI.Bootstrap.TagHelpers.Form
             isCheckbox = IsInputCheckbox(context, output, inputTagHelperOutput.Attributes);
             AddFormControlClass(context, output, isCheckbox, inputTagHelperOutput);
             AddReadOnlyAttribute(inputTagHelperOutput);
+            AddPlaceholderAttribute(inputTagHelperOutput);
 
             return inputTagHelperOutput;
         }
@@ -172,6 +173,21 @@ namespace Volo.Abp.AspNetCore.Mvc.UI.Bootstrap.TagHelpers.Form
             }
         }
 
+        protected virtual void AddPlaceholderAttribute(TagHelperOutput inputTagHelperOutput)
+        {
+            if (inputTagHelperOutput.Attributes.ContainsName("placeholder"))
+            {
+                return;
+            }
+
+            var attribute = GetAttribute<Placeholder>(TagHelper.AspFor.ModelExplorer);
+
+            if (attribute != null)
+            {
+                inputTagHelperOutput.Attributes.Add("placeholder", attribute.Value);
+            }
+        }
+
         protected virtual bool IsInputCheckbox(TagHelperContext context, TagHelperOutput output, TagHelperAttributeList attributes)
         {
             return attributes.Any(a => a.Value != null && a.Name == "type" && a.Value.ToString() == "checkbox");

framework/src/Volo.Abp.AspNetCore.Mvc.UI.Bootstrap/TagHelpers/Form/Placeholder.cs

@@ -0,0 +1,18 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Threading.Tasks;
+
+namespace Volo.Abp.AspNetCore.Mvc.UI.Bootstrap.TagHelpers.Form
+{
+    [AttributeUsage(AttributeTargets.Property)]
+    public class Placeholder : Attribute
+    {
+        public string Value { get; set; }
+
+        public Placeholder(string value)
+        {
+            Value = value;
+        }
+    }
+}