1 files changed, 81 insertions, 0 deletions
diff --git a/FireBase/Query/FilterQuery.cs b/FireBase/Query/FilterQuery.cs
new file mode 100644
index 0000000..f9f6271
--- /dev/null
+++ b/FireBase/Query/FilterQuery.cs
@@ -0,0 +1,81 @@
+namespace Firebase.Database.Query 
+{
+    using System;
+    using System.Globalization;
+
+    /// <summary>
+    /// Represents a firebase filtering query, e.g. "?LimitToLast=10".
+    /// </summary>
+    public class FilterQuery : ParameterQuery 
+    {
+        private readonly Func<string> valueFactory;
+        private readonly Func<double> doubleValueFactory;
+        private readonly Func<bool> boolValueFactory;
+
+        /// <summary>
+        /// Initializes a new instance of the <see cref="FilterQuery"/> class.
+        /// </summary>
+        /// <param name="parent"> The parent. </param>
+        /// <param name="filterFactory"> The filter. </param>
+        /// <param name="valueFactory"> The value for filter. </param>
+        /// <param name="client"> The owning client. </param>  
+        public FilterQuery(FirebaseQuery parent, Func<string> filterFactory, Func<string> valueFactory, FirebaseClient client)
+            : base(parent, filterFactory, client)
+        {
+            this.valueFactory = valueFactory;
+        }
+
+        /// <summary>
+        /// Initializes a new instance of the <see cref="FilterQuery"/> class.
+        /// </summary>
+        /// <param name="parent"> The parent. </param>
+        /// <param name="filterFactory"> The filter. </param>
+        /// <param name="valueFactory"> The value for filter. </param>
+        /// <param name="client"> The owning client. </param>
+        public FilterQuery(FirebaseQuery parent, Func<string> filterFactory, Func<double> valueFactory, FirebaseClient client)
+            : base(parent, filterFactory, client)
+        {
+            this.doubleValueFactory = valueFactory;
+        }
+
+        /// <summary>
+        /// Initializes a new instance of the <see cref="FilterQuery"/> class.
+        /// </summary>
+        /// <param name="parent"> The parent. </param>
+        /// <param name="filterFactory"> The filter. </param>
+        /// <param name="valueFactory"> The value for filter. </param>
+        /// <param name="client"> The owning client. </param>
+        public FilterQuery(FirebaseQuery parent, Func<string> filterFactory, Func<bool> valueFactory, FirebaseClient client)
+            : base(parent, filterFactory, client)
+        {
+            this.boolValueFactory = valueFactory;
+        }
+
+        /// <summary>
+        /// The build url parameter.
+        /// </summary>
+        /// <param name="child"> The child. </param> 
+        /// <returns> Url parameter part of the resulting path. </returns> 
+        protected override string BuildUrlParameter(FirebaseQuery child)
+        {
+            if (this.valueFactory != null)
+            {
+                if(this.valueFactory() == null)
+                {
+                    return $"null";
+                }
+                return $"\"{this.valueFactory()}\"";
+            }
+            else if (this.doubleValueFactory != null)
+            {
+                return this.doubleValueFactory().ToString(CultureInfo.InvariantCulture);
+            }
+            else if (this.boolValueFactory != null)
+            {
+                return $"{this.boolValueFactory().ToString().ToLower()}";
+            }
+
+            return string.Empty;
+        }
+    }
+}