Merge pull request #278 from TransactionProcessing/task/#268_add_querystring_builder

Add QueryStringBuilder and tests

Author: StuartFerguson

Shared.Tests/QueryStringBuilderTests.cs

@@ -0,0 +1,101 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+using Microsoft.VisualStudio.TestPlatform.TestHost;
+using Shared.Web;
+using Shouldly;
+using Xunit;
+
+namespace Shared.Tests
+{
+    public class QueryStringBuilderTests
+    {
+        [Fact]
+        public void QueryStringBuilder_NoParameters_EmptyQueryStringReturned()
+        {
+            QueryStringBuilder builder = new QueryStringBuilder();
+
+            var queryString = builder.BuildQueryString();
+
+            queryString.ShouldBe(String.Empty);
+        }
+
+        [Fact]
+        public void QueryStringBuilder_SingleParameters_CorrectQueryStringReturned()
+        {
+            QueryStringBuilder builder = new QueryStringBuilder();
+
+            builder.AddParameter("param1", "testparam1");
+
+            var queryString = builder.BuildQueryString();
+
+            queryString.ShouldBe("param1=testparam1");
+        }
+
+        [Fact]
+        public void QueryStringBuilder_MultipleParameters_CorrectQueryStringReturned()
+        {
+            QueryStringBuilder builder = new QueryStringBuilder();
+
+            builder.AddParameter("param1", "testparam1");
+            builder.AddParameter("param2", "testparam2");
+
+            var queryString = builder.BuildQueryString();
+
+            queryString.ShouldBe("param1=testparam1&param2=testparam2");
+        }
+
+        static T GetDefaultGeneric<T>()
+        {
+            return default(T);
+        }
+
+        static object GetDefault(Type type)
+        {
+            // Create a generic method with reflection to get the default value
+            var method = typeof(QueryStringBuilderTests).GetMethod(nameof(GetDefaultGeneric), System.Reflection.BindingFlags.Static | System.Reflection.BindingFlags.NonPublic);
+            var genericMethod = method.MakeGenericMethod(type);
+            return genericMethod.Invoke(null, null);
+        }
+
+        [Theory]
+        [InlineData(typeof(Decimal))]
+        [InlineData(typeof(DateTime))]
+        [InlineData(typeof(Int32))]
+        [InlineData(typeof(Int16))]
+        public void QueryStringBuilder_AddParametersWithDefaultValue_NotIncludedInQueryStringReturned(Type t)
+        {
+            QueryStringBuilder builder = new QueryStringBuilder();
+
+            object defaultValue = GetDefault(t);
+
+            builder.AddParameter("param1", "testparam1");
+            builder.AddParameter("param2", defaultValue);
+
+            var queryString = builder.BuildQueryString();
+
+            queryString.Contains("param2").ShouldBeFalse();
+        }
+
+        [Theory]
+        [InlineData(typeof(Decimal))]
+        [InlineData(typeof(DateTime))]
+        [InlineData(typeof(Int32))]
+        [InlineData(typeof(Int16))]
+        public void QueryStringBuilder_AddParametersWithDefaultValue_AlwaysInclude_ParameterIncludedInQueryStringReturned(Type t)
+        {
+            QueryStringBuilder builder = new QueryStringBuilder();
+
+            object defaultValue = GetDefault(t);
+
+            builder.AddParameter("param1", "testparam1");
+            builder.AddParameter("param2", defaultValue, true);
+
+            var queryString = builder.BuildQueryString();
+
+            queryString.Contains("param2").ShouldBeTrue();
+        }
+    }
+}

Shared/Web/QueryStringBuilder.cs

@@ -0,0 +1,83 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+
+namespace Shared.Web
+{
+    public class QueryStringBuilder
+    {
+        private Dictionary<string, (object value, Boolean alwaysInclude)> parameters = new Dictionary<String, (Object value, Boolean alwaysInclude)>();
+
+        public QueryStringBuilder AddParameter(string key, object value, Boolean alwaysInclude = false)
+        {
+            this.parameters.Add(key, (value, alwaysInclude));
+            return this;
+        }
+
+        static Dictionary<string, object> FilterDictionary(Dictionary<string, (object value, Boolean alwaysInclude)> inputDictionary)
+        {
+            Dictionary<string, object> result = new Dictionary<string, object>();
+
+            foreach (KeyValuePair<String, (object value, Boolean alwaysInclude)> entry in inputDictionary)
+            {
+                if (entry.Value.value != null && !IsDefaultValue(entry.Value.value, entry.Value.alwaysInclude))
+                {
+                    result.Add(entry.Key, entry.Value.value);
+                }
+            }
+
+            return result;
+        }
+
+        static bool IsDefaultValue<T>(T value, Boolean alwaysInclude)
+        {
+            if (alwaysInclude)
+                return false;
+
+            Object? defaultValue = GetDefault(value.GetType());
+
+            if (defaultValue == null && value.GetType() == typeof(String))
+            {
+                defaultValue = String.Empty;
+            }
+            return defaultValue.Equals(value);
+        }
+
+        public static object GetDefault(Type t)
+        {
+            Func<object> f = GetDefault<object>;
+            return f.Method.GetGenericMethodDefinition().MakeGenericMethod(t).Invoke(null, null);
+        }
+
+        private static T GetDefault<T>()
+        {
+            return default(T);
+        }
+
+        public string BuildQueryString()
+        {
+            Dictionary<String, Object> filtered = FilterDictionary(this.parameters);
+
+            if (filtered.Count == 0)
+            {
+                return string.Empty;
+            }
+
+            StringBuilder queryString = new StringBuilder();
+
+            foreach (KeyValuePair<String, Object> kvp in filtered)
+            {
+                if (queryString.Length > 0)
+                {
+                    queryString.Append("&");
+                }
+
+                queryString.Append($"{Uri.EscapeDataString(kvp.Key)}={Uri.EscapeDataString(kvp.Value.ToString())}");
+            }
+
+            return queryString.ToString();
+        }
+    }
+}