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Merged
merged 5 commits into from
Feb 28, 2019
Merged

Remove reflection #618

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tmilnthorp Feb 27, 2019
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tmilnthorp Feb 27, 2019
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148 changes: 7 additions & 141 deletions UnitsNet.Serialization.JsonNet/UnitsNetJsonConverter.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -2,13 +2,9 @@
// Copyright 2013 Andreas Gullberg Larsen (andreas.larsen84@gmail.com). Maintained at https://github.com/angularsen/UnitsNet.

using System;
using System.Linq;
using System.Reflection;
using JetBrains.Annotations;
using Newtonsoft.Json;
using Newtonsoft.Json.Linq;
using UnitsNet.Serialization.JsonNet.Internal;
using UnitsNet.Units;

namespace UnitsNet.Serialization.JsonNet
{
Expand All @@ -26,11 +22,6 @@ namespace UnitsNet.Serialization.JsonNet
/// </remarks>
public class UnitsNetJsonConverter : JsonConverter
{
/// <summary>
/// Numeric value field of a quantity, typically of type double or decimal.
/// </summary>
private const string ValueFieldName = "_value";

/// <summary>
/// Reads the JSON representation of the object.
/// </summary>
Expand All @@ -46,29 +37,20 @@ public override object ReadJson(JsonReader reader, Type objectType, object exist
JsonSerializer serializer)
{
if (reader.ValueType != null)
{
return reader.Value;
}

object obj = TryDeserializeIComparable(reader, serializer);
// A null System.Nullable value or a comparable type was deserialized so return this
if (!(obj is ValueUnit vu))
{
return obj;
}

// "MassUnit.Kilogram" => "MassUnit" and "Kilogram"
string unitEnumTypeName = vu.Unit.Split('.')[0];
string unitEnumValue = vu.Unit.Split('.')[1];

// "MassUnit" => "Mass"
string quantityTypeName = unitEnumTypeName.Substring(0, unitEnumTypeName.Length - "Unit".Length);

// "UnitsNet.Units.MassUnit,UnitsNet"
string unitEnumTypeAssemblyQualifiedName = "UnitsNet.Units." + unitEnumTypeName + ",UnitsNet";

// "UnitsNet.Mass,UnitsNet"
string quantityTypeAssemblyQualifiedName = "UnitsNet." + quantityTypeName + ",UnitsNet";

// -- see http://stackoverflow.com/a/6465096/1256096 for details
Type unitEnumType = Type.GetType(unitEnumTypeAssemblyQualifiedName);
if (unitEnumType == null)
Expand All @@ -78,63 +60,10 @@ public override object ReadJson(JsonReader reader, Type objectType, object exist
throw ex;
}

Type quantityType = Type.GetType(quantityTypeAssemblyQualifiedName);
if (quantityType == null)
{
var ex = new UnitsNetException("Unable to find unit type.");
ex.Data["type"] = quantityTypeAssemblyQualifiedName;
throw ex;
}

double value = vu.Value;
object unitValue = Enum.Parse(unitEnumType, unitEnumValue); // Ex: MassUnit.Kilogram

return CreateQuantity(quantityType, value, unitValue);
}

/// <summary>
/// Creates a quantity (ex: Mass) based on the reflected quantity type, a numeric value and a unit value (ex: MassUnit.Kilogram).
/// </summary>
/// <param name="quantityType">Type of quantity, such as <see cref="Mass"/>.</param>
/// <param name="value">Numeric value.</param>
/// <param name="unitValue">The unit, such as <see cref="MassUnit.Kilogram"/>.</param>
/// <returns>The constructed quantity, such as <see cref="Mass"/>.</returns>
private static object CreateQuantity(Type quantityType, double value, object unitValue)
{
// We want the non-nullable return type, example candidates if quantity type is Mass:
// double Mass.From(double, MassUnit)
// double? Mass.From(double?, MassUnit)
MethodInfo notNullableFromMethod = quantityType
.GetDeclaredMethods()
.Single(m => m.Name == "From" && Nullable.GetUnderlyingType(m.ReturnType) == null);

// Of type QuantityValue
object quantityValue = GetFromMethodValueArgument(notNullableFromMethod, value);

// Ex: Mass.From(55, MassUnit.Gram)
// See ValueUnit about precision loss for quantities using decimal type.
return notNullableFromMethod.Invoke(null, new[] {quantityValue, unitValue});
}

/// <summary>
/// Returns numeric value wrapped as <see cref="QuantityValue"/>, based on the type of argument
/// of <paramref name="fromMethod"/>. Today this is always <see cref="QuantityValue"/>, but
/// we may extend to other types later such as QuantityValueDecimal.
/// </summary>
/// <param name="fromMethod">The reflected From(value, unit) method.</param>
/// <param name="value">The value to convert to the correct wrapper type.</param>
/// <returns></returns>
private static object GetFromMethodValueArgument(MethodInfo fromMethod, double value)
{
Type valueParameterType = fromMethod.GetParameters()[0].ParameterType;
if (valueParameterType == typeof(QuantityValue))
{
// We use this type that takes implicit cast from all number types to avoid explosion of method overloads that take a numeric value.
return (QuantityValue) value;
}
Enum unitValue = (Enum)Enum.Parse(unitEnumType, unitEnumValue); // Ex: MassUnit.Kilogram

throw new Exception(
$"The first parameter of the reflected quantity From() method was expected to be either UnitsNet.QuantityValue, but was instead {valueParameterType}.");
return Quantity.From(value, unitValue);
}

private static object TryDeserializeIComparable(JsonReader reader, JsonSerializer serializer)
Expand Down Expand Up @@ -182,74 +111,14 @@ public override void WriteJson(JsonWriter writer, object obj, JsonSerializer ser
return;
}

object quantityValue = GetValueOfQuantity(obj, quantityType); // double or decimal value
string quantityUnitName = GetUnitFullNameOfQuantity(obj, quantityType); // Example: "MassUnit.Kilogram"
IQuantity quantity = obj as IQuantity;

serializer.Serialize(writer, new ValueUnit
{
// See ValueUnit about precision loss for quantities using decimal type.
Value = Convert.ToDouble(quantityValue),
Unit = quantityUnitName
});
}

/// <summary>
/// Given quantity (ex: <see cref="Mass"/>), returns the full name (ex: "MassUnit.Kilogram") of the constructed unit given by the <see cref="Mass.Unit"/> property.
/// </summary>
/// <param name="obj">Quantity, such as <see cref="Mass"/>.</param>
/// <param name="quantityType">The type of <paramref name="obj"/>, passed in here to reuse a previous lookup.</param>
/// <returns>"MassUnit.Kilogram" for a mass quantity whose Unit property is MassUnit.Kilogram.</returns>
private static string GetUnitFullNameOfQuantity(object obj, Type quantityType)
{
// Get value of Unit property
PropertyInfo unitProperty = quantityType.GetProperty("Unit");
Enum quantityUnit = (Enum) unitProperty.GetValue(obj, null); // MassUnit.Kilogram

Type unitType = quantityUnit.GetType(); // MassUnit
return $"{unitType.Name}.{quantityUnit}"; // "MassUnit.Kilogram"
}

private static object GetValueOfQuantity(object value, Type quantityType)
{
FieldInfo valueField = GetPrivateInstanceField(quantityType, ValueFieldName);

// See ValueUnit about precision loss for quantities using decimal type.
object quantityValue = valueField.GetValue(value);
return quantityValue;
}

private static FieldInfo GetPrivateInstanceField(Type quantityType, string fieldName)
{
FieldInfo baseValueField;
try
{
baseValueField = quantityType
#if (NETSTANDARD1_0)
.GetTypeInfo()
.DeclaredFields
.Where(f => !f.IsPublic && !f.IsStatic)
#else
.GetFields(BindingFlags.NonPublic | BindingFlags.Instance | BindingFlags.DeclaredOnly)
#endif
.SingleOrDefault(f => f.Name == fieldName);
}
catch (InvalidOperationException)
{
var ex = new UnitsNetException($"Expected exactly one private field named [{fieldName}], but found multiple.");
ex.Data["type"] = quantityType;
ex.Data["fieldName"] = fieldName;
throw ex;
}

if (baseValueField == null)
{
var ex = new UnitsNetException("No private fields found in type.");
ex.Data["type"] = quantityType;
ex.Data["fieldName"] = fieldName;
throw ex;
}

return baseValueField;
Value = quantity.Value,
Unit = $"{quantity.QuantityInfo.UnitType.Name}.{quantity.Unit}" // Example: "MassUnit.Kilogram"
} );
}

/// <summary>
Expand Down Expand Up @@ -280,9 +149,7 @@ private class ValueUnit
public override bool CanConvert(Type objectType)
{
if (IsNullable(objectType))
{
return CanConvertNullable(objectType);
}

return objectType.Namespace != null &&
(objectType.Namespace.Equals(nameof(UnitsNet)) ||
Expand Down Expand Up @@ -314,6 +181,5 @@ protected virtual bool CanConvertNullable(Type objectType)
}

#endregion

}
}
4 changes: 2 additions & 2 deletions UnitsNet.Tests/UnitConverterTest.cs
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Expand Up @@ -79,9 +79,9 @@ public void ConvertByAbbreviation_ConvertsTheValueToGivenUnit(double expectedVal

[Theory]
[InlineData(1, "UnknownQuantity", "m", "cm")]
public void ConvertByAbbreviation_ThrowsQuantityNotFoundExceptionOnUnknownQuantity(double inputValue, string quantityTypeName, string fromUnit, string toUnit)
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Hm, why was this test case removed? Is it no longer relevant/valid?

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I see further down why, but I think we can keep the test case and test for UnitNotFoundException instead?

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It fails because it doesn't throw it any more 😃 Code is unnecessary.

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But.. I honestly don't know what result to expect when calling this method with these arguments? What results are we getting if not exception?

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It will also give UnitNotFoundException. I'll add it back and catch that.

public void ConvertByAbbreviation_ThrowsUnitNotFoundExceptionOnUnknownQuantity( double inputValue, string quantityTypeName, string fromUnit, string toUnit)
{
Assert.Throws<QuantityNotFoundException>(() => UnitConverter.ConvertByAbbreviation(inputValue, quantityTypeName, fromUnit, toUnit));
Assert.Throws<UnitNotFoundException>(() => UnitConverter.ConvertByAbbreviation(inputValue, quantityTypeName, fromUnit, toUnit));
}

[Theory]
Expand Down
3 changes: 2 additions & 1 deletion UnitsNet/QuantityNotFoundException.cs
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Original file line number Diff line number Diff line change
@@ -1,4 +1,4 @@
// Licensed under MIT No Attribution, see LICENSE file at the root.
// Licensed under MIT No Attribution, see LICENSE file at the root.
// Copyright 2013 Andreas Gullberg Larsen (andreas.larsen84@gmail.com). Maintained at https://github.com/angularsen/UnitsNet.

using System;
Expand All @@ -9,6 +9,7 @@ namespace UnitsNet
/// Quantity type was not found. This is typically thrown for dynamic conversions,
/// such as <see cref="UnitConverter.ConvertByName" />.
/// </summary>
[Obsolete("")]
public class QuantityNotFoundException : UnitsNetException
{
/// <inheritdoc />
Expand Down
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