using System;
using System.Collections;
using System.Collections.Generic;
using System.Diagnostics.CodeAnalysis;
using System.Globalization;
using System.Linq;
using System.Reflection;
namespace AspWithAzureExtensions.Areas.HelpPage.SampleGeneration
{
/// <summary>
/// This class will create an object of a given type and populate it with sample data.
/// </summary>
public class ObjectGenerator
{
private const int DefaultCollectionSize = 3;
private readonly SimpleTypeObjectGenerator SimpleObjectGenerator = new SimpleTypeObjectGenerator();
/// <summary>
/// Generates an object for a given type. The type needs to be public, have a public default constructor and settable public properties/fields. Currently it supports the following types:
/// Simple types: <see cref="int"/>, <see cref="string"/>, <see cref="Enum"/>, <see cref="DateTime"/>, <see cref="Uri"/>, etc.
/// Complex types: POCO types.
/// Nullables: <see cref="Nullable{T}"/>.
/// Arrays: arrays of simple types or complex types.
/// Key value pairs: <see cref="KeyValuePair{TKey,TValue}"/>
/// Tuples: <see cref="Tuple{T1}"/>, <see cref="Tuple{T1,T2}"/>, etc
/// Dictionaries: <see cref="IDictionary{TKey,TValue}"/> or anything deriving from <see cref="IDictionary{TKey,TValue}"/>.
/// Collections: <see cref="IList{T}"/>, <see cref="IEnumerable{T}"/>, <see cref="ICollection{T}"/>, <see cref="IList"/>, <see cref="IEnumerable"/>, <see cref="ICollection"/> or anything deriving from <see cref="ICollection{T}"/> or <see cref="IList"/>.
/// Queryables: <see cref="IQueryable"/>, <see cref="IQueryable{T}"/>.
/// </summary>
/// <param name="type">The type.</param>
/// <returns>An object of the given type.</returns>
public object GenerateObject(Type type)
{
return GenerateObject(type, new Dictionary<Type, object>());
}
[SuppressMessage("Microsoft.Design", "CA1031:DoNotCatchGeneralExceptionTypes", Justification = "Here we just want to return null if anything goes wrong.")]
private object GenerateObject(Type type, Dictionary<Type, object> createdObjectReferences)
{
try
{
if (SimpleTypeObjectGenerator.CanGenerateObject(type))
{
return SimpleObjectGenerator.GenerateObject(type);
}
if (type.IsArray)
{
return GenerateArray(type, DefaultCollectionSize, createdObjectReferences);
}
if (type.IsGenericType)
{
return GenerateGenericType(type, DefaultCollectionSize, createdObjectReferences);
}
if (type == typeof(IDictionary))
{
return GenerateDictionary(typeof(Hashtable), DefaultCollectionSize, createdObjectReferences);
}
if (typeof(IDictionary).IsAssignableFrom(type))
{
return GenerateDictionary(type, DefaultCollectionSize, createdObjectReferences);
}
if (type == typeof(IList) ||
type == typeof(IEnumerable) ||
type == typeof(ICollection))
{
return GenerateCollection(typeof(ArrayList), DefaultCollectionSize, createdObjectReferences);
}
if (typeof(IList).IsAssignableFrom(type))
{
return GenerateCollection(type, DefaultCollectionSize, createdObjectReferences);
}
if (type == typeof(IQueryable))
{
return GenerateQueryable(type, DefaultCollectionSize, createdObjectReferences);
}
if (type.IsEnum)
{
return GenerateEnum(type);
}
if (type.IsPublic || type.IsNestedPublic)
{
return GenerateComplexObject(type, createdObjectReferences);
}
}
catch
{
// Returns null if anything fails
return null;
}
return null;
}
private static object GenerateGenericType(Type type, int collectionSize, Dictionary<Type, object> createdObjectReferences)
{
Type genericTypeDefinition = type.GetGenericTypeDefinition();
if (genericTypeDefinition == typeof(Nullable<>))
{
return GenerateNullable(type, createdObjectReferences);
}
if (genericTypeDefinition == typeof(KeyValuePair<,>))
{
return GenerateKeyValuePair(type, createdObjectReferences);
}
if (IsTuple(genericTypeDefinition))
{
return GenerateTuple(type, createdObjectReferences);
}
Type[] genericArguments = type.GetGenericArguments();
if (genericArguments.Length == 1)
{
if (genericTypeDefinition == typeof(IList<>) ||
genericTypeDefinition == typeof(IEnumerable<>) ||
genericTypeDefinition == typeof(ICollection<>))
{
Type collectionType = typeof(List<>).MakeGenericType(genericArguments);
return GenerateCollection(collectionType, collectionSize, createdObjectReferences);
}
if (genericTypeDefinition == typeof(IQueryable<>))
{
return GenerateQueryable(type, collectionSize, createdObjectReferences);
}
Type closedCollectionType = typeof(ICollection<>).MakeGenericType(genericArguments[0]);
if (closedCollectionType.IsAssignableFrom(type))
{
return GenerateCollection(type, collectionSize, createdObjectReferences);
}
}
if (genericArguments.Length == 2)
{
if (genericTypeDefinition == typeof(IDictionary<,>))
{
Type dictionaryType = typeof(Dictionary<,>).MakeGenericType(genericArguments);
return GenerateDictionary(dictionaryType, collectionSize, createdObjectReferences);
}
Type closedDictionaryType = typeof(IDictionary<,>).MakeGenericType(genericArguments[0], genericArguments[1]);
if (closedDictionaryType.IsAssignableFrom(type))
{
return GenerateDictionary(type, collectionSize, createdObjectReferences);
}
}
if (type.IsPublic || type.IsNestedPublic)
{
return GenerateComplexObject(type, createdObjectReferences);
}
return null;
}
private static object GenerateTuple(Type type, Dictionary<Type, object> createdObjectReferences)
{
Type[] genericArgs = type.GetGenericArguments();
object[] parameterValues = new object[genericArgs.Length];
bool failedToCreateTuple = true;
ObjectGenerator objectGenerator = new ObjectGenerator();
for (int i = 0; i < genericArgs.Length; i++)
{
parameterValues[i] = objectGenerator.GenerateObject(genericArgs[i], createdObjectReferences);
failedToCreateTuple &= parameterValues[i] == null;
}
if (failedToCreateTuple)
{
return null;
}
object result = Activator.CreateInstance(type, parameterValues);
return result;
}
private static bool IsTuple(Type genericTypeDefinition)
{
return genericTypeDefinition == typeof(Tuple<>) ||
genericTypeDefinition == typeof(Tuple<,>) ||
genericTypeDefinition == typeof(Tuple<,,>) ||
genericTypeDefinition == typeof(Tuple<,,,>) ||
genericTypeDefinition == typeof(Tuple<,,,,>) ||
genericTypeDefinition == typeof(Tuple<,,,,,>) ||
genericTypeDefinition == typeof(Tuple<,,,,,,>) ||
genericTypeDefinition == typeof(Tuple<,,,,,,,>);
}
private static object GenerateKeyValuePair(Type keyValuePairType, Dictionary<Type, object> createdObjectReferences)
{
Type[] genericArgs = keyValuePairType.GetGenericArguments();
Type typeK = genericArgs[0];
Type typeV = genericArgs[1];
ObjectGenerator objectGenerator = new ObjectGenerator();
object keyObject = objectGenerator.GenerateObject(typeK, createdObjectReferences);
object valueObject = objectGenerator.GenerateObject(typeV, createdObjectReferences);
if (keyObject == null && valueObject == null)
{
// Failed to create key and values
return null;
}
object result = Activator.CreateInstance(keyValuePairType, keyObject, valueObject);
return result;
}
private static object GenerateArray(Type arrayType, int size, Dictionary<Type, object> createdObjectReferences)
{
Type type = arrayType.GetElementType();
Array result = Array.CreateInstance(type, size);
bool areAllElementsNull = true;
ObjectGenerator objectGenerator = new ObjectGenerator();
for (int i = 0; i < size; i++)
{
object element = objectGenerator.GenerateObject(type, createdObjectReferences);
result.SetValue(element, i);
areAllElementsNull &= element == null;
}
if (areAllElementsNull)
{
return null;
}
return result;
}
private static object GenerateDictionary(Type dictionaryType, int size, Dictionary<Type, object> createdObjectReferences)
{
Type typeK = typeof(object);
Type typeV = typeof(object);
if (dictionaryType.IsGenericType)
{
Type[] genericArgs = dictionaryType.GetGenericArguments();
typeK = genericArgs[0];
typeV = genericArgs[1];
}
object result = Activator.CreateInstance(dictionaryType);
MethodInfo addMethod = dictionaryType.GetMethod("Add") ?? dictionaryType.GetMethod("TryAdd");
MethodInfo containsMethod = dictionaryType.GetMethod("Contains") ?? dictionaryType.GetMethod("ContainsKey");
ObjectGenerator objectGenerator = new ObjectGenerator();
for (int i = 0; i < size; i++)
{
object newKey = objectGenerator.GenerateObject(typeK, createdObjectReferences);
if (newKey == null)
{
// Cannot generate a valid key
return null;
}
bool containsKey = (bool)containsMethod.Invoke(result, new object[] { newKey });
if (!containsKey)
{
object newValue = objectGenerator.GenerateObject(typeV, createdObjectReferences);
addMethod.Invoke(result, new object[] { newKey, newValue });
}
}
return result;
}
private static object GenerateEnum(Type enumType)
{
Array possibleValues = Enum.GetValues(enumType);
if (possibleValues.Length > 0)
{
return possibleValues.GetValue(0);
}
return null;
}
private static object GenerateQueryable(Type queryableType, int size, Dictionary<Type, object> createdObjectReferences)
{
bool isGeneric = queryableType.IsGenericType;
object list;
if (isGeneric)
{
Type listType = typeof(List<>).MakeGenericType(queryableType.GetGenericArguments());
list = GenerateCollection(listType, size, createdObjectReferences);
}
else
{
list = GenerateArray(typeof(object[]), size, createdObjectReferences);
}
if (list == null)
{
return null;
}
if (isGeneric)
{
Type argumentType = typeof(IEnumerable<>).MakeGenericType(queryableType.GetGenericArguments());
MethodInfo asQueryableMethod = typeof(Queryable).GetMethod("AsQueryable", new[] { argumentType });
return asQueryableMethod.Invoke(null, new[] { list });
}
return Queryable.AsQueryable((IEnumerable)list);
}
private static object GenerateCollection(Type collectionType, int size, Dictionary<Type, object> createdObjectReferences)
{
Type type = collectionType.IsGenericType ?
collectionType.GetGenericArguments()[0] :
typeof(object);
object result = Activator.CreateInstance(collectionType);
MethodInfo addMethod = collectionType.GetMethod("Add");
bool areAllElementsNull = true;
ObjectGenerator objectGenerator = new ObjectGenerator();
for (int i = 0; i < size; i++)
{
object element = objectGenerator.GenerateObject(type, createdObjectReferences);
addMethod.Invoke(result, new object[] { element });
areAllElementsNull &= element == null;
}
if (areAllElementsNull)
{
return null;
}
return result;
}
private static object GenerateNullable(Type nullableType, Dictionary<Type, object> createdObjectReferences)
{
Type type = nullableType.GetGenericArguments()[0];
ObjectGenerator objectGenerator = new ObjectGenerator();
return objectGenerator.GenerateObject(type, createdObjectReferences);
}
private static object GenerateComplexObject(Type type, Dictionary<Type, object> createdObjectReferences)
{
object result = null;
if (createdObjectReferences.TryGetValue(type, out result))
{
// The object has been created already, just return it. This will handle the circular reference case.
return result;
}
if (type.IsValueType)
{
result = Activator.CreateInstance(type);
}
else
{
ConstructorInfo defaultCtor = type.GetConstructor(Type.EmptyTypes);
if (defaultCtor == null)
{
// Cannot instantiate the type because it doesn't have a default constructor
return null;
}
result = defaultCtor.Invoke(new object[0]);
}
createdObjectReferences.Add(type, result);
SetPublicProperties(type, result, createdObjectReferences);
SetPublicFields(type, result, createdObjectReferences);
return result;
}
private static void SetPublicProperties(Type type, object obj, Dictionary<Type, object> createdObjectReferences)
{
PropertyInfo[] properties = type.GetProperties(BindingFlags.Public | BindingFlags.Instance);
ObjectGenerator objectGenerator = new ObjectGenerator();
foreach (PropertyInfo property in properties)
{
if (property.CanWrite)
{
object propertyValue = objectGenerator.GenerateObject(property.PropertyType, createdObjectReferences);
property.SetValue(obj, propertyValue, null);
}
}
}
private static void SetPublicFields(Type type, object obj, Dictionary<Type, object> createdObjectReferences)
{
FieldInfo[] fields = type.GetFields(BindingFlags.Public | BindingFlags.Instance);
ObjectGenerator objectGenerator = new ObjectGenerator();
foreach (FieldInfo field in fields)
{
object fieldValue = objectGenerator.GenerateObject(field.FieldType, createdObjectReferences);
field.SetValue(obj, fieldValue);
}
}
private class SimpleTypeObjectGenerator
{
private long _index = 0;
private static readonly Dictionary<Type, Func<long, object>> DefaultGenerators = InitializeGenerators();
[SuppressMessage("Microsoft.Maintainability", "CA1502:AvoidExcessiveComplexity", Justification = "These are simple type factories and cannot be split up.")]
private static Dictionary<Type, Func<long, object>> InitializeGenerators()
{
return new Dictionary<Type, Func<long, object>>
{
{ typeof(Boolean), index => true },
{ typeof(Byte), index => (Byte)64 },
{ typeof(Char), index => (Char)65 },
{ typeof(DateTime), index => DateTime.Now },
{ typeof(DateTimeOffset), index => new DateTimeOffset(DateTime.Now) },
{ typeof(DBNull), index => DBNull.Value },
{ typeof(Decimal), index => (Decimal)index },
{ typeof(Double), index => (Double)(index + 0.1) },
{ typeof(Guid), index => Guid.NewGuid() },
{ typeof(Int16), index => (Int16)(index % Int16.MaxValue) },
{ typeof(Int32), index => (Int32)(index % Int32.MaxValue) },
{ typeof(Int64), index => (Int64)index },
{ typeof(Object), index => new object() },
{ typeof(SByte), index => (SByte)64 },
{ typeof(Single), index => (Single)(index + 0.1) },
{
typeof(String), index =>
{
return String.Format(CultureInfo.CurrentCulture, "sample string {0}", index);
}
},
{
typeof(TimeSpan), index =>
{
return TimeSpan.FromTicks(1234567);
}
},
{ typeof(UInt16), index => (UInt16)(index % UInt16.MaxValue) },
{ typeof(UInt32), index => (UInt32)(index % UInt32.MaxValue) },
{ typeof(UInt64), index => (UInt64)index },
{
typeof(Uri), index =>
{
return new Uri(String.Format(CultureInfo.CurrentCulture, "http://webapihelppage{0}.com", index));
}
},
};
}
public static bool CanGenerateObject(Type type)
{
return DefaultGenerators.ContainsKey(type);
}
public object GenerateObject(Type type)
{
return DefaultGenerators[type](++_index);
}
}
}
}
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