Feature/NRediSearch-TAGS (#749)

* Tag feature added

NRediSearch/Client.cs

@@ -138,6 +138,31 @@ public async Task<SearchResult> SearchAsync(Query q)
             return new SearchResult(resp, !q.NoContent, q.WithScores, q.WithPayloads);
         }
 
+        /// <summary>
+        /// Return Distinct Values in a TAG field
+        /// </summary>
+        /// <param name="fieldName">TAG field name</param>
+        /// <returns>List of TAG field values</returns>
+        public RedisValue[] TagVals(string fieldName)
+        {
+            var resp = (RedisValue[])DbSync.Execute("FT.TAGVALS", _boxedIndexName, fieldName);
+            
+            return resp;
+        }
+
+        /// <summary>
+        /// Return Distinct Values in a TAG field
+        /// </summary>
+        /// <param name="fieldName">TAG field name</param>
+        /// <returns>List of TAG field values</returns>
+        public async Task<RedisValue[]> TagValsAsync(string fieldName)
+        {
+            var resp = (RedisValue[])await _db.ExecuteAsync("FT.TAGVALS", _boxedIndexName, fieldName).ConfigureAwait(false);
+            
+            return resp;
+        }
+
+
         /// <summary>
         /// Add a single document to the query
         /// </summary>

NRediSearch/Schema.cs

@@ -15,7 +15,8 @@ public enum FieldType
         {
             FullText,
             Geo,
-            Numeric
+            Numeric,
+            Tag
         }
 
         public class Field
@@ -40,6 +41,7 @@ object GetForRedis(FieldType type)
                         case FieldType.FullText: return "TEXT".Literal();
                         case FieldType.Geo: return "GEO".Literal();
                         case FieldType.Numeric: return "NUMERIC".Literal();
+                        case FieldType.Tag: return "TAG".Literal();
                         default: throw new ArgumentOutOfRangeException(nameof(type));
                     }
                 }
@@ -129,5 +131,36 @@ public Schema AddSortableNumericField(string name)
             return this;
         }
 
+        public class TagField : Field
+        {
+            public string Separator { get; }
+            internal TagField(string name, string separator = ",") : base(name, FieldType.Tag, false)
+            {
+                Separator = separator;
+            }
+            internal override void SerializeRedisArgs(List<object> args)
+            {
+                base.SerializeRedisArgs(args);
+                if (Separator != ",")
+                {
+                    args.Add("SEPARATOR".Literal());
+                    args.Add(Separator);
+                }
+            }
+        }
+
+        /// <summary>
+        /// Add a TAG field
+        /// </summary>
+        /// <param name="name">the field's name</param>
+        /// <param name="separator">tag separator</param>
+        /// <returns>the schema object</returns>
+        public Schema AddTagField(string name, string separator = ",")
+        {
+            Fields.Add(new TagField(name, separator));
+            return this;
+        }
+
+
     }
 }