I have a routine (written with the generous help of others here) that allows me to take a List objects, and using any number of properties in any order it dynamically builds a TreeView structure with a Count at each node. This dynamic ability is a firm user requirement.
So a source List of:
{Prop1 = "A", Prop2 = "I", Prop3 = "X"},
{Prop1 = "A", Prop2 = "J", Prop3 = "X"},
{Prop1 = "B", Prop2 = "I", Prop3 = "X"},
{Prop1 = "B", Prop2 = "I", Prop3 = "Y"},
{Prop1 = "C", Prop2 = "K", Prop3 = "Z"}
Gives the following when the Selection is by Prop1 by Prop3:
Total (5)
- A(2)
- - X(2)
- B(2)
- - X(1)
- - Y(1)
- C(1)
- - Z(1)
Functionally this works fine. However, the performance leaves a lot to be desired when the number of distinct values increases. For example - one particular run in a dataset with 5K objects and 1K distinct values in Prop1 will take several seconds.
Here is the routine:
public static class TreeBuilder
{
public static Dictionary<string, TreeItem> BuildTree<TSource>(List<TSource> source, List<string> columns)
{
return new Dictionary<string, TreeItem>()
{
{ "Total",
new TreeItem()
{
Key = "Total",
RawKey = "Total",
Count = source.Count,
Items = GroupBySelector<TSource>(source, columns, 0, "Total")
}
}
};
}
public static MethodInfo GetGenericMethod(this Type type, string name, Type[] genericTypeArgs, Type[] paramTypes)
{
foreach (MethodInfo method in type.GetMethods())
if (method.Name == name)
{
var pa = method.GetParameters();
if (pa.Length == paramTypes.Length)
{
var genericMethod = method.MakeGenericMethod(genericTypeArgs);
if (genericMethod.GetParameters().Select(p => p.ParameterType).SequenceEqual(paramTypes))
return genericMethod;
}
}
return null;
}
private static MethodInfo GetGroupByMethodStatically<TElement, TKey>()
=> typeof(Enumerable).GetGenericMethod("GroupBy", new[] { typeof(TElement), typeof(TKey) }, new[] { typeof(IEnumerable<TElement>), typeof(Func<TElement, TKey>) });
private static MethodInfo GetEnumerableMethod(string methodName, Type tElement, Type tTKey)
{
var tIElement = typeof(IEnumerable<>).MakeGenericType(tElement);
var tFunction = typeof(Func<,>).MakeGenericType(tElement, tTKey);
return typeof(Enumerable).GetGenericMethod(methodName, new[] { tElement, tTKey }, new[] { tIElement, tFunction });
}
private static MethodInfo GetEnumerableMethod(string methodName, Type tElement)
{
var tIELEMENT = typeof(IEnumerable<>).MakeGenericType(tElement);
return typeof(Enumerable).GetGenericMethod(methodName, new[] { tElement }, new[] { tIELEMENT });
}
public static Dictionary<string, TreeItem> GroupBySelector<TElement>(IEnumerable<TElement> source, IList<string> columnNames, int entry = 0, string key = "")
{
if (source == null) throw new ArgumentNullException(nameof(source));
List<string> columnParameters = columnNames[entry].Split('|').ToList();
string columnName = columnParameters[0];
if (columnName == null) throw new ArgumentNullException(nameof(columnName));
if (columnName.Length == 0) throw new ArgumentException(nameof(columnName));
int nextEntry = entry + 1;
var tElement = typeof(TElement);
var tIElement = typeof(IEnumerable<TElement>);
var keyParm = Expression.Parameter(tElement);
var prop = Expression.Property(keyParm, columnName);
var param = Expression.Parameter(tIElement, "p");
var groupByMethod = GetEnumerableMethod("GroupBy", tElement, prop.Type);
var groupByExpr = Expression.Lambda(prop, keyParm);
var bodyExprCall = Expression.Call(groupByMethod, param, groupByExpr);
var tSelectInput = typeof(IGrouping<,>).MakeGenericType(prop.Type, tElement);
var selectParam = Expression.Parameter(tSelectInput, "p");
var tKey = typeof(TreeItem).GetMember("Key").Single();
var tRawKey = typeof(TreeItem).GetMember("RawKey").Single();
var tCount = typeof(TreeItem).GetMember("Count").Single();
var tParentKey = typeof(TreeItem).GetMember("ParentKey").Single();
var tItems = typeof(TreeItem).GetMember("Items").Single();
Expression selectParamKey = Expression.Property(selectParam, "Key");
Expression selectParamRawKey = selectParamKey;
if (selectParamKey.Type != typeof(string))
{
var toStringMethod = selectParamKey.Type.GetMethod("ToString", Type.EmptyTypes);
selectParamKey = Expression.Call(selectParamKey, toStringMethod);
}
if (selectParamRawKey.Type != typeof(string))
{
var toStringMethod = selectParamRawKey.Type.GetMethod("ToString", Type.EmptyTypes);
selectParamRawKey = Expression.Call(selectParamRawKey, toStringMethod);
}
var countMethod = GetEnumerableMethod("Count", tElement);
var countMethodExpr = Expression.Call(countMethod, selectParam);
var concatFullKeyExpr = Expression.Call(typeof(string).GetMethod("Concat", new[] { typeof(string), typeof(string), typeof(string) }),
Expression.Constant(key),
Expression.Constant("|"),
selectParamRawKey);
var groupBySelectorMethod = GetGenericMethod(MethodBase.GetCurrentMethod().DeclaringType, "GroupBySelector", new[] { tElement }, new[] { tIElement, typeof(IList<string>), typeof(int), typeof(string) });
var groupBySelectorMethodExpr = Expression.Call(groupBySelectorMethod, selectParam, Expression.Constant(columnNames), Expression.Constant(nextEntry), concatFullKeyExpr);
var newMenuItemExpr = Expression.New(typeof(TreeItem));
var selectBodyExpr = Expression.MemberInit(newMenuItemExpr, new[] {
Expression.Bind(tKey, selectParamKey),
Expression.Bind(tRawKey, selectParamRawKey),
Expression.Bind(tParentKey, Expression.Constant(key) ),
Expression.Bind(tCount, countMethodExpr),
Expression.Bind(tItems, groupBySelectorMethodExpr)
});
var selectBodyExprLamba = Expression.Lambda(selectBodyExpr, selectParam);
var selectBodyLastExpr = Expression.MemberInit(newMenuItemExpr, new[] {
Expression.Bind(tKey, selectParamKey),
Expression.Bind(tRawKey, selectParamRawKey),
Expression.Bind(tParentKey, Expression.Constant(key) ),
Expression.Bind(tCount, countMethodExpr)
});
var selectBodyLastExprLambda = Expression.Lambda(selectBodyLastExpr, selectParam);
var selectMethod = GetEnumerableMethod("Select", tSelectInput, typeof(TreeItem));
bodyExprCall = Expression.Call(selectMethod, bodyExprCall, (nextEntry < columnNames.Count) ? selectBodyExprLamba : selectBodyLastExprLambda);
var selectParamout = Expression.Parameter(typeof(TreeItem), "o");
Expression selectParamKeyout = Expression.Property(selectParamout, "FullKey");
var selectParamKeyLambda = Expression.Lambda(selectParamKeyout, selectParamout);
var lmi = GetEnumerableMethod("ToDictionary", typeof(TreeItem), typeof(string));
bodyExprCall = Expression.Call(lmi, bodyExprCall, selectParamKeyLambda);
var returnFunc = Expression.Lambda<Func<IEnumerable<TElement>, Dictionary<string, TreeItem>>>(bodyExprCall, param).Compile();
return returnFunc(source);
}
}
The routine is used to take data from a DB table and convert it into a hierarchical structure for use in a WPF TreeView.
Dictionary<string, TreeItem> treeItems = new Dictionary<string, TreeItem>();
treeItems = TreeBuilder.BuildTree<IDBRecord>(DBService.GetDBRecordList(), PropertySortList);
Can anyone offer any advice on how to improve the performance of this routine? Or suggest any alternative way of achieving the same result in a more performant way?
Thanks
A couple of optimizations are possible. A lot of time is spent in the call to Compile and you are calling Compile for each key at each level in the tree, which is adding up to a lot of overhead, about 7 seconds on my tests of 5k items. I first changed the code to pull out all static Reflection that had fixed types, so it is only done once per program run. That only made a small difference, since building the Expression tree is not the main issue.
I then changed the method to separate building the Expression from compiling the Expression and calling the resultant lambda. This allowed me to modify the recursive call to the Expression builder to instead be an inline Invoke of a new lambda for the new level. Then I called compile once on the resulting Expression and executed it. The new version no longer takes the entry parameter, but it could be put back in.
This reduced the overall time from about 7.6 seconds to 0.14 seconds for around a 50x speedup. A test with all three properties resulted in a 280x speedup.
If it is still possible for repeated calls to the method, adding a cache would be of even more benefit, though a quick test only shows about 14% time savings, and in the hundredths of a second of real time.
static MemberInfo tKey = typeof(TreeItem).GetMember("Key").Single();
static MemberInfo tRawKey = typeof(TreeItem).GetMember("RawKey").Single();
static MemberInfo tCount = typeof(TreeItem).GetMember("Count").Single();
static MemberInfo tParentKey = typeof(TreeItem).GetMember("ParentKey").Single();
static MemberInfo tItems = typeof(TreeItem).GetMember("Items").Single();
// Concat(string, string, string)
static MethodInfo Concat3MI = ((Func<string, string, string, string>)String.Concat).Method;
// new TreeItem() { ... }
static NewExpression newMenuItemExpr = Expression.New(typeof(TreeItem));
// Enumerable.ToDictionary<TreeItem>(IEnumerable<TreeItem>, Func<TreeItem,string>)
static MethodInfo ToDictionaryMI = GetEnumerableMethod("ToDictionary", typeof(TreeItem), typeof(string));
static Expression<Func<IEnumerable<TElement>, Dictionary<string, TreeItem>>> BuildGroupBySelector<TElement>(IList<string> columnNames, int entry, Expression key) {
List<string> columnParameters = columnNames[entry].Split('|').ToList();
string columnName = columnParameters[0];
if (columnName == null) throw new ArgumentNullException(nameof(columnName));
if (columnName.Length == 0) throw new ArgumentException(nameof(columnName));
int nextEntry = entry + 1;
var tElement = typeof(TElement);
var tIElement = typeof(IEnumerable<TElement>);
// (TElement kp)
var keyParm = Expression.Parameter(tElement, "kp");
// kp.columnName
var prop = Expression.Property(keyParm, columnName);
// (IEnumerable<TElement> p)
var IEParam = Expression.Parameter(tIElement, "p");
// GroupBy<TElement>(IEnumerable<TElement>, Func<TElement, typeof(kp.columnName)>)
var groupByMethod = GetEnumerableMethod("GroupBy", tElement, prop.Type);
// kp => kp.columnName
var groupByExpr = Expression.Lambda(prop, keyParm);
// GroupBy(p, kp => kp.columnName)
var bodyExprCall = Expression.Call(groupByMethod, IEParam, groupByExpr);
// typeof(IGrouping<typeof(kp.columnName), TElement>)
var tSelectInput = typeof(IGrouping<,>).MakeGenericType(prop.Type, tElement);
// (IGrouping<typeof(kp.columnName), TElement> sp)
var selectParam = Expression.Parameter(tSelectInput, "sp");
// sp.Key
Expression selectParamKey = Expression.Property(selectParam, "Key");
Expression selectParamRawKey = selectParamKey;
if (selectParamKey.Type != typeof(string)) {
var toStringMethod = selectParamKey.Type.GetMethod("ToString", Type.EmptyTypes);
// sp.Key.ToString()
selectParamKey = Expression.Call(selectParamKey, toStringMethod);
selectParamRawKey = selectParamKey;
}
// Count<TElement>()
var countMethod = GetEnumerableMethod("Count", tElement);
// sp.Count()
var countMethodExpr = Expression.Call(countMethod, selectParam);
LambdaExpression selectBodyExprLamba;
if (nextEntry < columnNames.Count) {
// Concat(key, "|", sp.Key.ToString())
var concatFullKeyExpr = Expression.Call(Concat3MI, key, Expression.Constant("|"), selectParamRawKey);
// p# => p#.GroupBy().Select().ToDictionary()
var groupBySelectorLambdaExpr = BuildGroupBySelector<TElement>(columnNames, nextEntry, (Expression)concatFullKeyExpr);
// Invoke(p# => p#..., sp#)
var groupBySelectorInvokeExpr = Expression.Invoke(groupBySelectorLambdaExpr, selectParam);
var selectBodyExpr = Expression.MemberInit(newMenuItemExpr, new[] {
Expression.Bind(tKey, selectParamKey),
Expression.Bind(tRawKey, selectParamRawKey),
Expression.Bind(tParentKey, key ),
Expression.Bind(tCount, countMethodExpr),
Expression.Bind(tItems, groupBySelectorInvokeExpr)
});
// sp => new TreeItem { Key = sp.Key.ToString(), RawKey = sp.Key.ToString(), ParentKey = key, Count = sp.Count(), Items = Invoke(p# => p#..., sp)) }
selectBodyExprLamba = Expression.Lambda(selectBodyExpr, selectParam);
}
else { // Last Level
var selectBodyExpr = Expression.MemberInit(newMenuItemExpr, new[] {
Expression.Bind(tKey, selectParamKey),
Expression.Bind(tRawKey, selectParamRawKey),
Expression.Bind(tParentKey, key ),
Expression.Bind(tCount, countMethodExpr)
});
// sp => new TreeItem { Key = sp.Key.ToString(), RawKey = sp.Key.ToString(), ParentKey = key, Count = sp.Count() }
selectBodyExprLamba = Expression.Lambda(selectBodyExpr, selectParam);
}
// Enumerable.Select<IGrouping<typeof<kp.columnName>, TElement>>(IEnumerable<IGrouping<>>, Func<IGrouping<>, TreeItem>)
var selectMethod = GetEnumerableMethod("Select", tSelectInput, typeof(TreeItem));
// p.GroupBy(kp => kp => kp.columnName).Select(sp => ...)
bodyExprCall = Expression.Call(selectMethod, bodyExprCall, selectBodyExprLamba);
// (TreeItem o)
var selectParamout = Expression.Parameter(typeof(TreeItem), "o");
// o.FullKey
Expression selectParamKeyout = Expression.Property(selectParamout, "FullKey");
// o => o.FullKey
var selectParamKeyLambda = Expression.Lambda(selectParamKeyout, selectParamout);
// p.GroupBy(...).Select(...).ToDictionary(o => o.FullKey)
bodyExprCall = Expression.Call(ToDictionaryMI, bodyExprCall, selectParamKeyLambda);
// p => p.GroupBy(kp => kp => kp.columnName).Select(sp => ...).ToDictionary(o => o.FullKey)
return Expression.Lambda<Func<IEnumerable<TElement>, Dictionary<string, TreeItem>>>(bodyExprCall, IEParam);
}
public static Dictionary<string, TreeItem> GroupBySelector<TElement>(IEnumerable<TElement> source, IList<string> columnNames, string key = "") {
if (source == null) throw new ArgumentNullException(nameof(source));
// p => p.GroupBy(kp => kp => kp.columnName).Select(sp => ...).ToDictionary(o => o.FullKey)
var returnFunc = BuildGroupBySelector<TElement>(columnNames, 0, Expression.Constant(key)).Compile();
return returnFunc(source);
}
I'm trying to dynamically create an predicate to pass into a linq where clause. This is for a generic method that takes two list of the same Type and and list of property names to compare.
void SomeMethod<T>(List<T> oldRecords, List<T> newRecords, List<string> propertiesOfT)
{
// dynamically build predicate for this
var notMatch = oldRecords.Where(o => !newRecords.Any(n => n.Prop1 == o.Prop1 && n.Prop2 == o.Prop2)).ToList();
// do somethind with notMatch
}
I would like to convert this:
var notMatch = oldRecords.Where(o => !newRecords.Any(n => n.Prop1 == o.Prop1 && n.Prop2 == o.Prop2)).ToList();
To achieve this:
var predicate = "n => n.Prop1 == o.Prop1 && n.Prop2 == o.Prop2"; // sudo code
var notMatch = oldRecords.Where(o => !newRecords.Any(predicate));
or this
var predicate = "o => !newRecords.Any(n => n.Prop1 == o.Prop1 && n.Prop2 == o.Prop2)" // sudo code
var notMatch = oldRecords.Where(predicate);
How do I populate newRecords when dynamically creating the Expression?
And how would I reference parameter o and parameter n in the Expresssion.
I've gotten this far:
//construct the two parameters
var o = Expression.Parameter(typeof(T), "o");
var n = Expression.Parameter(typeof(T), "n");
// How to I go about populating o with values and n with values
// from oldRecords and newRecords? or is that no neccessary
var property = Expression.Property(o, typeof(T).GetProperty("Id").Name);
var value = Expression.Constant(Convert.ChangeType("12345", typeof(T).GetProperty("Id").PropertyType), typeof(T).GetProperty("Id").PropertyType);
BinaryExpression binaryExpression = Expression.MakeBinary(ExpressionType.Equal, property, value);
Any sudo code or clue where to look to achieve this?
With reflection it's quite easy. You just to have to think about it. Here's the working version.
void SomeMethod<T>(List<T> oldRecords, List<T> newRecords, List<string> propertiesOfT)
{
// get the list of property to match
var properties = propertiesOfT.Select(prop => typeof(T).GetProperty(prop)).ToList();
// Get all old record where we don't find any matching new record where all the property equal that old record
var notMatch = oldRecords.Where(o => !newRecords.Any(n => properties.All(prop => prop.GetValue(o).Equals(prop.GetValue(n))))).ToList();
}
And here's a sample set i tried and it works
public class test
{
public int id { get; set; } = 0;
public string desc { get; set; } = "";
public test(string s, int i)
{
desc = s;id = i;
}
}
private void Main()
{
var oldRecords = new List<test>()
{
new test("test",1),
new test("test",2)
};
var newRecords = new List<test>()
{
new test("test1",1),
new test("test",2)
};
SomeMethod(oldRecords, newRecords, new List<string>() { "id", "desc" });
}
I want to convert flowing expression
person.Name = "John";
Expression<Func<Person, bool>> exp = x => x.Name == person.Name && x.Age > 20;
to string like this:
(x.Name == "John") AndAlso (x.Age > 20)
I use exp.ToString(); method but the result is:
(x.Name == value(MyNamespace.MyClass+<>c__DisplayClass0).person.Name) AndAlso (x.Age > 20)
How can i convert expression correctly?
The problem is that your expression references a variable from scope in a closure, and what you need is a constant expression.
You can rewrite the expression tree with an ExpressionVisitor so it eliminates memeber accesses leading to a constant:
namespace FixVisitor
{
class Program
{
static void Main(string[] args)
{
var person = new Person();
person.Name = "John";
Expression<Func<Person, bool>> exp = x => x.Name == person.Name && x.Age > 20;
var modified = new FixVisitor().Visit(exp);
Console.WriteLine(modified);
}
}
class FixVisitor : ExpressionVisitor
{
bool IsMemeberAccessOfAConstant(Expression exp)
{
if (exp.NodeType == ExpressionType.MemberAccess)
{
var memberAccess = (MemberExpression) exp;
if (memberAccess.Expression.NodeType == ExpressionType.Constant)
return true;
return IsMemeberAccessOfAConstant(memberAccess.Expression);
}
return false;
}
protected override Expression VisitMember(MemberExpression node)
{
if (IsMemeberAccessOfAConstant(node) && node.Type == typeof(string))
{
var item = Expression.Lambda<Func<string>>(node);
var value = item.Compile()();
return Expression.Constant(value, typeof(string));
}
return base.VisitMember(node);
}
}
class Person
{
public string Name { get; set; }
public int Age { get; set; }
}
}
To do what you want, you have to treat person.Name as constant, so I think that you have to build the Expression at runtime:
var pers = Expression.Parameter(typeof(Person), "x"); //The parameter to the expression(its type and its name)
var propName = Expression.Property(pers, "Name"); // The property "Name" of the parameter(x.Name)
var nameAsConstant = Expression.Constant(person.Name); // The value I will compare to x.Name
var equal = Expression.Equal(propName, nameAsConstant); // The comparison(x.Name == "John")
var propAge = Expression.Property(pers, "Age"); // The property "Age" of the parameter(x.Age)
var ageConstant = Expression.Constant(20); // The value I will compare to x.Age
var greater = Expression.GreaterThan(propAge, ageConstant); // The comparison(x.Age > 20)
var conditions = Expression.AndAlso(equal, greater); // Merging the expression with && [(x.Name == "John") AndAlso (x.Age > 20)]
var lambda = Expression.Lambda<Func<Person, bool>>(conditions, pers); // Build the expression
var lambdaStr = lambda.ToString(); //x => ((x.Name == "John") AndAlso (x.Age > 20))
If you need only ((x.Name == "John") AndAlso (x.Age > 20)) just do conditions.ToString();
i wrote function
private Func<CategorizedPosts, bool> CompileExpression(IEnumerable<Category> categories)
{
Expression predicateBody;
ParameterExpression pe = Expression.Parameter(typeof(CategorizedPosts), "post");
Expression left = Expression.Property(pe, typeof(CategorizedPosts).GetProperty("CATEGORY_ID"));
Expression right = Expression.Constant(categories.ElementAt(0).ID);
Expression equal = Expression.Equal(left, right);
predicateBody = equal;
for (int i = 1, j = categories.Count() - 1; i < categories.Count(); ++i )
{
var category = categories.ElementAt(i);
//y => y.CATEGORY_ID == 1 || y.CATEGORY_ID == 2)
left = Expression.Property(pe, typeof(CategorizedPosts).GetProperty("CATEGORY_ID"));
right = Expression.Constant(category.ID);
equal = Expression.Equal(left, right);
predicateBody = Expression.OrElse(predicateBody, equal);
}
var lll = Expression.Lambda<Func<CategorizedPosts, bool>>(predicateBody, pe);
var compiled = lll.Compile();
return compiled;
}
it compiles OK, but when I try to run this query
var ctx = db.Posts.Where(x => true);
if(predicate != null)
{
ctx = ctx.Where(x => x.CategorizedPosts.Where(**predicate**).Count() > 0);
}
IList<Post> posts = ctx.OrderByDescending(x => x.CREATION_DATE).Skip((page - 1) * perPage).Take(perPage).Select(x => new Post
{
POST_ID = x.ID,
TYPE = new Type { ID = x.TYPE_ID, NAME = x.Types.NAME },
AUTHOR = new Author()
{
ID = x.AUTHOR_ID,
NAME = x.Authors.NAME,
},
CATEGORIES = x.CategorizedPosts.Select(y => new Category() { ID = y.CATEGORY_ID, NAME = y.Categories.NAME }),
CREATION_DATE = x.CREATION_DATE,
}).ToList();
EF throws exception about internal error 1025 for Entity Data Provider. How can I perform this query with dynamic where?
You could use the Contains of a collection of Ids (int) and apply it on a where, for sample:
int[] categorieIds = categories.Select(x => x.Id).ToArray();
ctx = ctx.Where(x => x.CategorizedPosts.Any(c => categorieIds .Contains(c.Id));
Some Tips
Remember the Entity Framework works with Expression<Func<T, bool>> in the Where method, not only Func<T, bool>.
You also could try to apply PredicateBuilder class which provides some extensions methods like Or, And, Not, so, you could try this:
var predicate = PredicateBuilder.False<Product>();
foreach (string keyword in keywords)
{
string temp = keyword;
predicate = predicate.Or (p => p.Description.Contains (temp));
}
return dataContext.Products.Where(predicate).ToList();
How to build dynamic lambda function like below?
item => item.AnalyzeData.Any(subitem =>
subitem.DepartmentIDs.Any(subitem2 => subitem2 == "abc"))
AnalyzeData is custom class array type, DepartmentIDs is string array type
The class of AnalyzeData has DepartmentIDs Property
So how to dynamic generator the above lambda expression via expression tree.
After some research, the problem has been resolved. now share the solution code to others who has the some issue.
[TestMethod]
[Description("Dynamic generate lambda expression")]
public void DynamicGenerateMethod1()
{
Item item1 = new Item()
{
ItemID = "test1",
AnalyzeData = new ItemAnalyzeData[]
{
new ItemAnalyzeData()
{
DepartmentIDs = new []{"Department1","Department2"}
},
}
};
Item item2 = new Item()
{
ItemID = "test2",
AnalyzeData = new ItemAnalyzeData[]
{
new ItemAnalyzeData()
{
DepartmentIDs = new []{"Department3","Department4"}
},
}
};
Expression<Func<Item, bool>> expectedExpression =
item => item.AnalyzeData.Any(subitem => subitem.DepartmentIDs.Any(subitem2 => subitem2 == "Department3"));
//Get Enumerable.Any generic method
var anyPredicate =
typeof(Enumerable).GetMethods().First(m => m.Name == "Any" && m.GetParameters().Length == 2);
#region Build inner most lambda expression : subitem2 => subitem2 == "Department3"
var subitem2Para = Expression.Parameter(typeof(string), "subitem2");
var subitem2CompareValue = Expression.Equal(subitem2Para, Expression.Constant("Department3", typeof(string)));
var subitem2CompareFun = Expression.Lambda<Func<string, bool>>(subitem2CompareValue, subitem2Para);
#endregion
#region Build center lambda expression : subitem => subitem.DepartmentIDs.Any( ... )
var subitemPara = Expression.Parameter(typeof(ItemAnalyzeData), "subitem");
var departmentIDsAnyMethodCall = anyPredicate.MakeGenericMethod(typeof(string));
var subItemDepartmentIDsCall = Expression.Call(departmentIDsAnyMethodCall, Expression.Property(subitemPara, "DepartmentIDs"), subitem2CompareFun);
var subitemCompareFun = Expression.Lambda<Func<ItemAnalyzeData, bool>>(subItemDepartmentIDsCall, subitemPara);
#endregion
#region Build outer most lambda expression : item => item.AnalyzeData.Any( ... )
var itemExpr = Expression.Parameter(typeof(Item), "item");
var analyzeAnyMethodCall = anyPredicate.MakeGenericMethod(typeof(ItemAnalyzeData));
var itemAnalyzeDataCall = Expression.Call(analyzeAnyMethodCall, Expression.Property(itemExpr, "AnalyzeData"), subitemCompareFun);
var itemCompareFun = Expression.Lambda<Func<Item, bool>>(itemAnalyzeDataCall, itemExpr);
#endregion
var method = itemCompareFun.Compile();
var actualLambdaCode = itemCompareFun.ToString();
var expectLambdaCode = expectedExpression.ToString();
Assert.AreEqual(expectLambdaCode, actualLambdaCode);
Assert.IsFalse(method.Invoke(item1));
Assert.IsTrue(method.Invoke(item2));
}