[FIX] nullable conversions (#3316)

* Fix nullable conversions

* Fix when passing null, instead of string.Empty

* Fix compiler error

Co-authored-by: Tomáš Filip <[email protected]>

Author: tomasfil

src/ReactiveUI/Bindings/Converter/NullableByteToStringTypeConverter.cs

@@ -44,8 +44,20 @@ public bool TryConvert(object? from, Type toType, object? conversionHint, out ob
             return true;
         }
 
+        if (from is null)
+        {
+            result = null!;
+            return true;
+        }
+
         if (from is string fromString)
         {
+            if (string.IsNullOrEmpty(fromString))
+            {
+                result = null!;
+                return true;
+            }
+
             var success = byte.TryParse(fromString, out var outByte);
             if (success)
             {

src/ReactiveUI/Bindings/Converter/NullableDecimalToStringTypeConverter.cs

@@ -44,8 +44,20 @@ public bool TryConvert(object? from, Type toType, object? conversionHint, out ob
             return true;
         }
 
+        if (from is null)
+        {
+            result = null!;
+            return true;
+        }
+
         if (from is string fromString)
         {
+            if (string.IsNullOrEmpty(fromString))
+            {
+                result = null!;
+                return true;
+            }
+
             var success = decimal.TryParse(fromString, out var outDecimal);
             if (success)
             {

src/ReactiveUI/Bindings/Converter/NullableDoubleToStringTypeConverter.cs

@@ -44,8 +44,20 @@ public bool TryConvert(object? from, Type toType, object? conversionHint, out ob
             return true;
         }
 
+        if (from is null)
+        {
+            result = null!;
+            return true;
+        }
+
         if (from is string fromString)
         {
+            if (string.IsNullOrEmpty(fromString))
+            {
+                result = null!;
+                return true;
+            }
+
             var success = double.TryParse(fromString, out var outDouble);
             if (success)
             {

src/ReactiveUI/Bindings/Converter/NullableIntegerToStringTypeConverter.cs

@@ -44,8 +44,20 @@ public bool TryConvert(object? from, Type toType, object? conversionHint, out ob
             return true;
         }
 
+        if (from is null)
+        {
+            result = null!;
+            return true;
+        }
+
         if (from is string fromString)
         {
+            if (string.IsNullOrEmpty(fromString))
+            {
+                result = null!;
+                return true;
+            }
+
             var success = int.TryParse(fromString, out var outInt);
             if (success)
             {

src/ReactiveUI/Bindings/Converter/NullableLongToStringTypeConverter.cs

@@ -44,8 +44,20 @@ public bool TryConvert(object? from, Type toType, object? conversionHint, out ob
             return true;
         }
 
+        if (from is null)
+        {
+            result = null!;
+            return true;
+        }
+
         if (from is string fromString)
         {
+            if (string.IsNullOrEmpty(fromString))
+            {
+                result = null!;
+                return true;
+            }
+
             var success = long.TryParse(fromString, out var outLong);
             if (success)
             {

src/ReactiveUI/Bindings/Converter/NullableShortToStringTypeConverter.cs

@@ -44,8 +44,20 @@ public bool TryConvert(object? from, Type toType, object? conversionHint, out ob
             return true;
         }
 
+        if (from is null)
+        {
+            result = null!;
+            return true;
+        }
+
         if (from is string fromString)
         {
+            if (string.IsNullOrEmpty(fromString))
+            {
+                result = null!;
+                return true;
+            }
+
             var success = short.TryParse(fromString, out var outShort);
             if (success)
             {

src/ReactiveUI/Bindings/Converter/NullableSingleToStringTypeConverter.cs

@@ -44,8 +44,20 @@ public bool TryConvert(object? from, Type toType, object? conversionHint, out ob
             return true;
         }
 
+        if (from is null)
+        {
+            result = null!;
+            return true;
+        }
+
         if (from is string fromString)
         {
+            if (string.IsNullOrEmpty(fromString))
+            {
+                result = null!;
+                return true;
+            }
+
             var success = float.TryParse(fromString, out var outSingle);
             if (success)
             {