1 files changed, 77 insertions, 0 deletions
diff --git a/dsa/FireBase/Query/FilterQuery.cs b/dsa/FireBase/Query/FilterQuery.cs
new file mode 100644
index 0000000..3434d1d
--- /dev/null
+++ b/dsa/FireBase/Query/FilterQuery.cs
@@ -0,0 +1,77 @@
+using System;
+using System.Globalization;
+
+namespace Firebase.Database.Query
+{
+    /// <summary>
+    ///     Represents a firebase filtering query, e.g. "?LimitToLast=10".
+    /// </summary>
+    public class FilterQuery : ParameterQuery
+    {
+        private readonly Func<bool> boolValueFactory;
+        private readonly Func<double> doubleValueFactory;
+        private readonly Func<string> 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<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)
+        {
+            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)
+        {
+            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 (valueFactory != null)
+            {
+                if (valueFactory() == null) return "null";
+                return $"\"{valueFactory()}\"";
+            }
+
+            if (doubleValueFactory != null)
+                return doubleValueFactory().ToString(CultureInfo.InvariantCulture);
+            if (boolValueFactory != null) return $"{boolValueFactory().ToString().ToLower()}";
+
+            return string.Empty;
+        }
+    }
+}
+\ No newline at end of file