Develop Reference

Project on update/create (set values from another object en masse) in LINQ2DB?

When using LINQ2DB for my application I tried to use entity-DTO mapping using Expression<Func<Entity, DTO>> and vice versa like described here: https://github.com/linq2db/linq2db/issues/1283#issuecomment-413509043
This works great for projecting using a select, but what do I do when I need to update/insert a new record? I've skimmed over Update and Set extension methods but couldn't find anything.
What I am trying to achieve is basically expression-based two-way mapping between an entity class and a DTO, kinda like AutoMapper's projection for EF but manually written per-DTO, in the form of two expressions for two-way conversion.
Sadly I am not an expert in expression trees and LINQ to SQL translation, so would appreciate if anyone suggests something that works like this:
Expression<Func<SomeDTO, SomeEntityTable>> projectExpr =
x => new SomeEntity
{
ID = x.ID,
Name = x.Name,
// ...
}; // this is just so that I can write two mapping expressions per DTO and don't ever repeat them, for stuff like CRUD
// ...
using var db = ConnectionFactory.Instance.GetMainDB();
await db.SomeEntityTable
.Where(e => e.ID == dto.ID)
.Set(dto, projectExpr) // dto is of SomeDTO type here; this will set ONLY the values that are written in the expression
.Set(e => e.LastEditedAt, DateTime.Now()) // able to append some more stuff after
.UpdateAsync();
// similar for insert operation, using the same expression

These extension methods should provide needed mapping:
using var db = ConnectionFactory.Instance.GetMainDB();
await db.SomeEntityTable
.Where(e => e.ID == dto.ID)
.AsUpdatable()
.Set(dto, projectExpr) // new extension method
.Set(e => e.LastEditedAt, DateTime.Now())
.UpdateAsync();
await db.SomeEntityTable
.AsValueInsertable()
.Values(dto, projectExpr) // new extension method
.Value(e => e.LastEditedAt, DateTime.Now())
.InsertAsync();
And implementation:
public static class InsertUpdateExtensions
{
private static MethodInfo _withIUpdatable = Methods.LinqToDB.Update.SetUpdatableExpression;
private static MethodInfo _withIValueInsertable = Methods.LinqToDB.Insert.VI.ValueExpression;
public static IUpdatable<TEntity> Set<TEntity, TDto>(
this IUpdatable<TEntity> updatable,
TDto obj,
Expression<Func<TDto, TEntity>> projection)
{
var body = projection.GetBody(Expression.Constant(obj));
var entityParam = Expression.Parameter(typeof(TEntity), "e");
var pairs = EnumeratePairs(body, entityParam);
foreach (var pair in pairs)
{
updatable = (IUpdatable<TEntity>)_withIUpdatable.MakeGenericMethod(typeof(TEntity), pair.Item1.Type)
.Invoke(null,
new object?[]
{
updatable,
Expression.Lambda(pair.Item1, entityParam),
Expression.Lambda(pair.Item2)
})!;
}
return updatable;
}
public static IValueInsertable<TEntity> Values<TEntity, TDto>(
this IValueInsertable<TEntity> insertable,
TDto obj,
Expression<Func<TDto, TEntity>> projection)
{
var body = projection.GetBody(Expression.Constant(obj));
var entityParam = Expression.Parameter(typeof(TEntity), "e");
var pairs = EnumeratePairs(body, entityParam);
foreach (var pair in pairs)
{
insertable = (IValueInsertable<TEntity>)_withIValueInsertable.MakeGenericMethod(typeof(TEntity), pair.Item1.Type)
.Invoke(null,
new object?[]
{
insertable,
Expression.Lambda(pair.Item1, entityParam),
Expression.Lambda(pair.Item2)
})!;
}
return insertable;
}
private static IEnumerable<Tuple<Expression, Expression>> EnumeratePairs(Expression projection, Expression entityPath)
{
switch (projection.NodeType)
{
case ExpressionType.MemberInit:
{
var mi = (MemberInitExpression)projection;
foreach (var b in mi.Bindings)
{
if (b.BindingType == MemberBindingType.Assignment)
{
var assignment = (MemberAssignment)b;
foreach (var p in EnumeratePairs(Expression.MakeMemberAccess(entityPath, assignment.Member),
assignment.Expression))
{
yield return p;
}
}
}
break;
}
case ExpressionType.New:
{
var ne = (NewExpression)projection;
if (ne.Members != null)
{
for (var index = 0; index < ne.Arguments.Count; index++)
{
var expr = ne.Arguments[index];
var member = ne.Members[index];
foreach (var p in EnumeratePairs(Expression.MakeMemberAccess(entityPath, member), expr))
{
yield return p;
}
}
}
break;
}
case ExpressionType.MemberAccess:
{
yield return Tuple.Create(projection, entityPath);
break;
}
default:
throw new NotImplementedException();
}
}
}

How do I convert a BigQuery row to JSON using the C# API?

I am pulling some data from a BigQuery table using the code below in C#
BigQueryClient client = BigQueryClient.Create("<Project Name>");
BigQueryTable table = client.GetTable("<Database>", "Students");
string sql = $"select * FROM {table} where Marks='50'";
BigQueryResults results = client.ExecuteQuery(sql);
foreach (BigQueryRow row in results.GetRows())
{
}
I want to be able to either read the entire results variable into JSON or be able to get the JSON out of each row.
Of course, I could create a class that models the table. And inside the foreach loop, I could just read each row into the class object. The class object I can try to serialize into JSON using a third party like "newton soft".
Something like :
class Student{
int id; // assume these are columns in the db
string name;
}
My foreach would now look like:
foreach (BigQueryRow row in results.GetRows())
{
Student s=new Student();
s.id = Convert.ToString(row["id"]);
s.name= Convert.ToString(row["name"]);
// something like string x=x+ s.toJSON(); //using newton soft
}
This way string x will have the JSON generated and appended for each row.
Or is there a way I can just add each student to a collection or List and then get the JSON from the whole list?
This whole reading row by row and field by field seems tedious to me and there must be a simpler way I feel. Did not see any support from Google BigQuery for C# to directly convert to JSON. They did have something in Python.
If not then the list to JSON would be better but I am not sure if it supported.
Update :
https://github.com/GoogleCloudPlatform/google-cloud-dotnet/blob/master/apis/Google.Cloud.BigQuery.V2/Google.Cloud.BigQuery.V2/BigQueryRow.cs
Looks like the Big Query Row class has a RawRow field which is of Type TableRow. And the class uses JSON references so , I am sure they have the data of the row in JSON format . How can I expose it to me ?

This might be a little late but you can use:
var latestResult = _bigQueryClient.ExecuteQuery($"SELECT TO_JSON_STRING(t) FROM `{ProjectId}.{DatasetId}.{TableName}` as t", null
All columns will be serialized as json and placed in the first column on each row. You can then use something like Newtonsoft to parse each row easily.

I ran into the same issue.
I am posting this solution which is not optimized for performance but very simple for multiple data types.
This allows you to deserialize anything (almost)
public class BQ
{
private string projectId = "YOUR_PROJECT_ID";
public BQ()
{
}
public List<T> Execute<T>(string sql)
{
var client = BigQueryClient.Create(projectId);
List<T> result = new List<T>();
try
{
string query = sql;
BigQueryResults results = client.ExecuteQuery(query, parameters: null);
List<string> fields = new List<string>();
foreach (var col in results.Schema.Fields)
{
fields.Add(col.Name);
}
Dictionary<string, object> rowoDict;
foreach (var row in results)
{
rowoDict = new Dictionary<string, object>();
foreach (var col in fields)
{
rowoDict.Add(col, row[col]);
}
string json = Newtonsoft.Json.JsonConvert.SerializeObject(rowoDict);
T o = Newtonsoft.Json.JsonConvert.DeserializeObject<T>(json);
result.Add(o);
}
}
catch (Exception ex)
{
Console.WriteLine(ex.ToString());
}
finally
{
client.Dispose();
Console.WriteLine("Done.");
}
return result;
}
}

You can use Newtonsoft.Json. First download by PackageManager Console the Nuget Package, here you can get the command to do that.
After download you can use it as the following code:
List<Student> list = new List<Student>();
foreach (BigQueryRow row in results.GetRows())
{
Student s=new Student();
s.id = Convert.ToString(row["id"]);
s.name= Convert.ToString(row["name"]);
list.Add(s);
}
var jsonResult = Newtonsoft.Json.JsonConvert.SerializeObject(list);
I hope this can help you.

Here is the complete solution for casting BigQueryResults or GetQueryResultsResponse or QueryResponse data to Model/JSON format using C# reflection:
public List<T> GetBQAsModel<T>(string query) where T : class, new()
{
var bqClient = GetBigqueryClient();
var res = bqClient.ExecuteQuery(query, parameters: null);
return GetModels<T>(res);
}
private List<T> GetModels<T>(BigQueryResults tableRows) where T : class, new()
{
var lst = new List<T>();
foreach (var item in tableRows)
{
var lstColumns = new T().GetType().GetProperties(BindingFlags.DeclaredOnly | BindingFlags.Instance | BindingFlags.Public | BindingFlags.NonPublic).ToList();
var newObject = new T();
for (var i = 0; i < item.RawRow.F.Count; i++)
{
var name = item.Schema.Fields[i].Name;
PropertyInfo prop = lstColumns.FirstOrDefault(a => a.Name.ToLower().Equals(name.ToLower()));
if (prop == null)
{
continue;
}
var val = item.RawRow.F[i].V;
prop.SetValue(newObject, Convert.ChangeType(val, prop.PropertyType), null);
}
lst.Add(newObject);
}
return lst;
}
private List<T> GetModels<T>(GetQueryResultsResponse getQueryResultsResponse) where T : class, new()
{
var lst = new List<T>();
foreach (var item in getQueryResultsResponse.Rows)
{
var lstColumns = new T().GetType().GetProperties(BindingFlags.DeclaredOnly | BindingFlags.Instance | BindingFlags.Public | BindingFlags.NonPublic).ToList();
var newObject = new T();
for (var i = 0; i < item.F.Count; i++)
{
var name = getQueryResultsResponse.Schema.Fields[i].Name;
PropertyInfo prop = lstColumns.FirstOrDefault(a => a.Name.ToLower().Equals(name.ToLower()));
if (prop == null)
{
continue;
}
var val = item.F[i].V;
prop.SetValue(newObject, Convert.ChangeType(val, prop.PropertyType), null);
}
lst.Add(newObject);
}
return lst;
}
private List<T> GetModels<T>(QueryResponse queryResponse) where T : class, new()
{
var lst = new List<T>();
foreach (var item in queryResponse.Rows)
{
var lstColumns = new T().GetType().GetProperties(BindingFlags.DeclaredOnly | BindingFlags.Instance | BindingFlags.Public | BindingFlags.NonPublic).ToList();
var newObject = new T();
for (var i = 0; i < item.F.Count; i++)
{
var name = queryResponse.Schema.Fields[i].Name;
PropertyInfo prop = lstColumns.FirstOrDefault(a => a.Name.ToLower().Equals(name.ToLower()));
if (prop == null)
{
continue;
}
var val = item.F[i].V;
prop.SetValue(newObject, Convert.ChangeType(val, prop.PropertyType), null);
}
lst.Add(newObject);
}
return lst;
}

I would do something like this:
var res = Result. Getrows. Select(x=> new student(){id=x[`ID']}).
And then:
var js = json. Conver(res);
This way is much faster and clearer.

C# using ExpressionTree to map DataTable to List<T>

I have written a ToList(); extension Method to convert a DataTable to List. This just works under some circumstances but we have much old code which uses DataTables and sometimes it's needed. My Problem is that this method works with reflection what is ok but not that performant. I need about 1,2sek for 100.000 DataRows.
So i decided to build this with Expression Trees. At first i want to replace the Setter Call of Properties. Up to this time i could easily get the value:
var exactType = Nullable.GetUnderlyingType(propType) ?? propType;
var wert = Convert.ChangeType(zeile[spaltenname], exactType);
and set it:
propertyInfo.SetValue(tempObjekt, wert, null);
Now i searched StackOverflow and found this:
var zielExp = Expression.Parameter(typeof(T));
var wertExp = Expression.Parameter(propType);
var propertyExp = Expression.Property(zielExp, matchProp);
var zuweisungExp = Expression.Assign(propertyExp, wertExp);
var setter = Expression.Lambda<Action<T, int>>(zuweisungExp, zielExp, wertExp).Compile();
setter(tempObjekt, wert);
My big Problem is that the Lambda Action expects an integer. But i need this expecting the type of my Property. I have the Type of my Property via PropertyInfo. But can't get this to work. Thought i can easily make:
Action<T, object>
but this results in following excepion:
ArgumentException The ParameterExpression from Type "System.Int32"
cannot be used as Delegateparameter from Type "System.Object".
Someone out there knows a possible solution?

Instead of the generic Expression.Lambda method you can use this overload which takes a type:
public static LambdaExpression Lambda(
Type delegateType,
Expression body,
params ParameterExpression[] parameters
)
Then you can use the Type.MakeGenericType method to create the type for your action:
var actionType = typeof(Action<,>).MakeGenericType(typeof(T), proptype);
var setter = Expression.Lambda(actionType, zuweisungExp, zielExp, wertExp).Compile();
Edit following the comments regarding performance:
You can also just build the expression runtime to map the DataTable to your class of type T with a select, so there's only need to use reflection once, which should greatly improve performance. I wrote the following extension method to convert a DataTable to List<T> (note that this method will throw a runtime exception if you don't plan to map all datacolumns to a property in the class, so be sure to take care of that if that might happen):
public static class LocalExtensions
{
public static List<T> DataTableToList<T>(this DataTable table) where T : class
{
//Map the properties in a dictionary by name for easy access
var propertiesByName = typeof(T)
.GetProperties(BindingFlags.Public | BindingFlags.Instance)
.ToDictionary(p => p.Name);
var columnNames = table.Columns.Cast<DataColumn>().Select(dc => dc.ColumnName);
//The indexer property to access DataRow["columnName"] is called "Item"
var property = typeof(DataRow).GetProperties().First(p => p.Name == "Item"
&& p.GetIndexParameters().Length == 1
&& p.GetIndexParameters()[0].ParameterType == typeof(string));
var paramExpr = Expression.Parameter(typeof(DataRow), "r");
var newExpr = Expression.New(typeof(T));
//Create the expressions to map properties from your class to the corresponding
//value in the datarow. This will throw a runtime exception if your class
//doesn't contain properties for all columnnames!
var memberBindings = columnNames.Select(columnName =>
{
var pi = propertiesByName[columnName];
var indexExpr = Expression.MakeIndex(paramExpr, property,
new[] { Expression.Constant(columnName) });
//Datarow["columnName"] is of type object, cast to the right type
var convert = Expression.Convert(indexExpr, pi.PropertyType);
return Expression.Bind(pi, convert);
});
var initExpr = Expression.MemberInit(newExpr, memberBindings);
var func = Expression.Lambda<Func<DataRow, T>>(initExpr,paramExpr).Compile();
return table.Rows.Cast<DataRow>().Select(func).ToList();
}
}
Then I wrote a small testclass and some code which creates a datatable of 1,000,000 rows that get mapped to a list. Building the expression + converting to a list now only takes 486ms on my pc (granted it is a very small class of course):
class Test
{
public string TestString { get; set; }
public int TestInt { get; set; }
}
class Program
{
static void Main()
{
DataTable table = new DataTable();
table.Columns.Add(new DataColumn("TestString", typeof(string)));
table.Columns.Add(new DataColumn("TestInt", typeof(int)));
for(int i = 0; i < 1000000; i++)
{
var row = table.NewRow();
row["TestString"] = $"String number: {i}";
row["TestInt"] = i;
table.Rows.Add(row);
}
var stopwatch = Stopwatch.StartNew();
var myList = table.DataTableToList<Test>();
stopwatch.Stop();
Console.WriteLine(stopwatch.Elapsed.ToString());
}
}

I think I've understood you correctly. I cannot translate your variables so I'm taking my best guess here based on what I'm seeing in your question:
For an Action<object,object> where the first parameter is the Entity itself and the second is the type of the property you can use
var instance = Expression.Parameter(typeof(object), "i");
var argument = Expression.Parameter(typeof(object), "a");
var convertObj = Expression.TypeAs(instance, propertyInfo.DeclaringType);
var convert = Expression.Convert(argument, propertyInfo.PropertyType);
var setterCall = Expression.Call(convertObj, propertyInfo.GetSetMethod(), convert);
var compiled = ((Expression<Action<object, object>>) Expression.Lambda(setterCall, instance, argument)).Compile();
If you know T (ie, the type of the Entity), you can do this instead:
var instance = Expression.Parameter(typeof(T), "i");
var argument = Expression.Parameter(typeof(object), "a");
var convert = Expression.Convert(argument, propertyInfo.PropertyType);
var setterCall = Expression.Call(instance , propertyInfo.GetSetMethod(), convert);
var compiled = ((Expression<Action<T, object>>) Expression.Lambda(setterCall, instance, argument)).Compile();

I comment here because I do not have the necessary reputation to comment on the response of #Alexander Derek
var memberBindings = columnNames.Select(columnName =>
{
var pi = propertiesByName[columnName];
var indexExpr = Expression.MakeIndex(paramExpr, property,
new[] { Expression.Constant(columnName) });
//Datarow["columnName"] is of type object, cast to the right type
var convert = Expression.Convert(indexExpr, pi.PropertyType);
return Expression.Bind(pi, convert);
});
in order to avoid runtime exception i added a try-catch and .where()
var memberBindings = columnNames.Select(columnName =>
{
try
{
var pi = propertiesByName[columnName];
var indexExpr = Expression.MakeIndex(paramExpr, property,
new[] { Expression.Constant(columnName) });
var convert = Expression.Convert(indexExpr, pi.PropertyType);
return Expression.Bind(pi, convert);
}
catch(Exception e)
{
return null;
}
});
var initExpr = Expression.MemberInit(newExpr, memberBindings.Where(obj => obj != null));

Generic Method of Searching all Fields within an IEnumerable for any match in c#

I code below that works well with an API for the DataTables plugin; for each column that the DataTables searches in, regardless of type, the filter works as expected based on what is supplied.
DataTables also has a "Global" search feature where you can search in one field and if there is a match in ANY of the rows for said data then a match is returned.
What I am Hoping For:
A way to perform a search on an IEnumerable such that if any of the fields match the search the result is returned.
NameValueCollection nvc = HttpUtility.ParseQueryString(Request.RequestUri.Query);
var generalSearch = nvc["sSearch"];
if (!string.IsNullOrWhiteSpace(generalSearch))
{
var generalSearchProperties = typeof(T).GetProperties();
foreach (var currentProperty in generalSearchProperties)
{
Type propType = currentProperty.PropertyType;
set = set.Where(StaticUtility.PropertyEquals<T>(currentProperty, generalSearch, propType));
/* ^^^^^ */
/*
Instead of the "Where" here I am looking for something like "where or" which can be added to the IEnumerable.
*/
}
}
Original Code:
protected virtual IQueryable<T> FilterEntitiesBySearchParameters(IQueryable<T> set)
{
try
{
NameValueCollection nvc = HttpUtility.ParseQueryString(Request.RequestUri.Query);
var props = typeof(T).GetProperties();
foreach (var prop in props)
{
var name = prop.Name;
var val = nvc[name];
Type propType = prop.PropertyType;
if (val != null)
{
set = set.Where(StaticUtility.PropertyEquals<T>(prop, val, propType));
}
if (nvc.GetPairs().Where(p => p.Value == name).Where(p => p.Key.StartsWith("mDataProp")).Any())
{
var key = nvc.GetPairs().Where(p => p.Value == name).Where(p => p.Key.StartsWith("mDataProp")).FirstOrDefault().Key;
key = key.Replace("mDataProp", "sSearch");
val = nvc[key];
if (!String.IsNullOrEmpty(val))
set = set.Where(StaticUtility.PropertyEquals<T>(prop, val, propType));
}
}
return set;
} catch (Exception exc)
{
return set;
}
}

If I understand your request correctly, you basically want to search through your data and match any field for equality? If that's true, then simply add your matching data to a new set, and filter it by .Distinct() after the fact, to make sure you get one record of each. Something like so...
NameValueCollection nvc = HttpUtility.ParseQueryString(Request.RequestUri.Query);
var results = new IEnumerable<T>();
var generalSearch = nvc["sSearch"];
if (!string.IsNullOrWhiteSpace(generalSearch))
{
var generalSearchProperties = typeof(T).GetProperties();
foreach (var currentProperty in generalSearchProperties)
{
Type propType = currentProperty.PropertyType;
results.AddRange(set.Where(StaticUtility.PropertyEquals<T>(currentProperty, generalSearch, propType)));
}
}
return results.Distinct();

You could try to first create a BinaryExpression consisting of all the different options, then pass that expression to the Where() method of the query.
Assuming your StaticUtility class is used to create expressions, you might try something like the following:
NameValueCollection nvc = HttpUtility.ParseQueryString(Request.RequestUri.Query);
// Container for filter expression
BinaryExpression filter = null;
var generalSearch = nvc["sSearch"];
if (!string.IsNullOrWhiteSpace(generalSearch)) {
var generalSearchProperties = typeof(T).GetProperties();
foreach (var currentProperty in generalSearchProperties) {
Type propType = currentProperty.PropertyType;
if (filter == null) {
// Start with first filter expression
filter = StaticUtility.PropertyEquals<T>(currentProperty, generalSearch, propType);
} else {
// Add another filter using OR
BinaryExpression other = StaticUtility.PropertyEquals<T>(currentProperty, generalSearch, propType);
filter = BinaryExpression.OrElse(filter, other);
}
}
}
// Add actual filter to query
set = set.Where(filter);

C# deep/nested/recursive merge of dynamic/expando objects

I need to "merge" 2 dynamic objects in C#. All that I've found on stackexchange covered only non-recursive merging. But I am looking to something that does recursive or deep merging, very much the same like jQuery's $.extend(obj1, obj2) function.
Upon collision of two members, the following rules should apply:
If the types mismatch, an exception must be thrown and merge is aborted. Exception: obj2 Value maybe null, in this case the value & type of obj1 is used.
For trivial types (value types + string) obj1 values are always prefered
For non-trivial types, the following rules are applied:
IEnumerable & IEnumberables<T> are simply merged (maybe .Concat() ? )
IDictionary & IDictionary<TKey,TValue> are merged; obj1 keys have precedence upon collision
Expando & Expando[] types must be merged recursively, whereas Expando[] will always have same-type elements only
One can assume there are no Expando objects within Collections (IEnumerabe & IDictionary)
All other types can be discarded and need not be present in the resulting dynamic object
Here is an example of a possible merge:
dynamic DefaultConfig = new {
BlacklistedDomains = new string[] { "domain1.com" },
ExternalConfigFile = "blacklist.txt",
UseSockets = new[] {
new { IP = "127.0.0.1", Port = "80"},
new { IP = "127.0.0.2", Port = "8080" }
}
};
dynamic UserSpecifiedConfig = new {
BlacklistedDomain = new string[] { "example1.com" },
ExternalConfigFile = "C:\\my_blacklist.txt"
};
var result = Merge (UserSpecifiedConfig, DefaultConfig);
// result should now be equal to:
var result_equal = new {
BlacklistedDomains = new string[] { "domain1.com", "example1.com" },
ExternalConfigFile = "C:\\my_blacklist.txt",
UseSockets = new[] {
new { IP = "127.0.0.1", Port = "80"},
new { IP = "127.0.0.2", Port = "8080" }
}
};
Any ideas how to do this?

Right, this is a bit longwinded but have a look. it's an implementation using Reflection.Emit.
Open issue for me is how to implement a ToString() override so that you can do a string comparison. Are these values coming from a config file or something? If they are in JSON Format you could do worse than use a JsonSerializer, I think. Depends on what you want.
You could use the Expando Object to get rid of the Reflection.Emit nonsense as well, at the bottom of the loop:
var result = new ExpandoObject();
var resultDict = result as IDictionary<string, object>;
foreach (string key in resVals.Keys)
{
resultDict.Add(key, resVals[key]);
}
return result;
I can't see a way around the messy code for parsing the original object tree though, not immediately. I'd like to hear some other opinions on this. The DLR is relatively new ground for me.
using System;
using System.Collections.Generic;
using System.Diagnostics;
using System.Linq;
using System.Reflection;
using System.Reflection.Emit;
using System.Runtime.CompilerServices;
using System.Threading;
namespace ConsoleApplication1
{
class Program
{
static void Main(string[] args)
{
dynamic DefaultConfig = new
{
BlacklistedDomains = new string[] { "domain1.com" },
ExternalConfigFile = "blacklist.txt",
UseSockets = new[] {
new { IP = "127.0.0.1", Port = "80" },
new { IP = "127.0.0.2", Port = "8080" }
}
};
dynamic UserSpecifiedConfig = new
{
BlacklistedDomains = new string[] { "example1.com" },
ExternalConfigFile = "C:\\my_blacklist.txt"
};
var result = Merge(UserSpecifiedConfig, DefaultConfig);
// result should now be equal to:
var result_equal = new
{
BlacklistedDomains = new string[] { "domain1.com", "example1.com" },
ExternalConfigFile = "C:\\my_blacklist.txt",
UseSockets = new[] {
new { IP = "127.0.0.1", Port = "80"},
new { IP = "127.0.0.2", Port = "8080" }
}
};
Debug.Assert(result.Equals(result_equal));
}
/// <summary>
/// Merge the properties of two dynamic objects, taking the LHS as primary
/// </summary>
/// <param name="lhs"></param>
/// <param name="rhs"></param>
/// <returns></returns>
static dynamic Merge(dynamic lhs, dynamic rhs)
{
// get the anonymous type definitions
Type lhsType = ((Type)((dynamic)lhs).GetType());
Type rhsType = ((Type)((dynamic)rhs).GetType());
object result = new { };
var resProps = new Dictionary<string, PropertyInfo>();
var resVals = new Dictionary<string, object>();
var lProps = lhsType.GetProperties().ToDictionary<PropertyInfo, string>(prop => prop.Name);
var rProps = rhsType.GetProperties().ToDictionary<PropertyInfo, string>(prop => prop.Name);
foreach (string leftPropKey in lProps.Keys)
{
var lPropInfo = lProps[leftPropKey];
resProps.Add(leftPropKey, lPropInfo);
var lhsVal = Convert.ChangeType(lPropInfo.GetValue(lhs, null), lPropInfo.PropertyType);
if (rProps.ContainsKey(leftPropKey))
{
PropertyInfo rPropInfo;
rPropInfo = rProps[leftPropKey];
var rhsVal = Convert.ChangeType(rPropInfo.GetValue(rhs, null), rPropInfo.PropertyType);
object setVal = null;
if (lPropInfo.PropertyType.IsAnonymousType())
{
setVal = Merge(lhsVal, rhsVal);
}
else if (lPropInfo.PropertyType.IsArray)
{
var bound = ((Array) lhsVal).Length + ((Array) rhsVal).Length;
var cons = lPropInfo.PropertyType.GetConstructor(new Type[] { typeof(int) });
dynamic newArray = cons.Invoke(new object[] { bound });
//newArray = ((Array)lhsVal).Clone();
int i=0;
while (i < ((Array)lhsVal).Length)
{
newArray[i] = lhsVal[i];
i++;
}
while (i < bound)
{
newArray[i] = rhsVal[i - ((Array)lhsVal).Length];
i++;
}
setVal = newArray;
}
else
{
setVal = lhsVal == null ? rhsVal : lhsVal;
}
resVals.Add(leftPropKey, setVal);
}
else
{
resVals.Add(leftPropKey, lhsVal);
}
}
foreach (string rightPropKey in rProps.Keys)
{
if (lProps.ContainsKey(rightPropKey) == false)
{
PropertyInfo rPropInfo;
rPropInfo = rProps[rightPropKey];
var rhsVal = rPropInfo.GetValue(rhs, null);
resProps.Add(rightPropKey, rPropInfo);
resVals.Add(rightPropKey, rhsVal);
}
}
Type resType = TypeExtensions.ToType(result.GetType(), resProps);
result = Activator.CreateInstance(resType);
foreach (string key in resVals.Keys)
{
var resInfo = resType.GetProperty(key);
resInfo.SetValue(result, resVals[key], null);
}
return result;
}
}
}
public static class TypeExtensions
{
public static Type ToType(Type type, Dictionary<string, PropertyInfo> properties)
{
AppDomain myDomain = Thread.GetDomain();
Assembly asm = type.Assembly;
AssemblyBuilder assemblyBuilder =
myDomain.DefineDynamicAssembly(
asm.GetName(),
AssemblyBuilderAccess.Run
);
ModuleBuilder moduleBuilder = assemblyBuilder.DefineDynamicModule(type.Module.Name);
TypeBuilder typeBuilder = moduleBuilder.DefineType(type.Name,TypeAttributes.Public);
foreach (string key in properties.Keys)
{
string propertyName = key;
Type propertyType = properties[key].PropertyType;
FieldBuilder fieldBuilder = typeBuilder.DefineField(
"_" + propertyName,
propertyType,
FieldAttributes.Private
);
PropertyBuilder propertyBuilder = typeBuilder.DefineProperty(
propertyName,
PropertyAttributes.HasDefault,
propertyType,
new Type[] { }
);
// First, we'll define the behavior of the "get" acessor for the property as a method.
MethodBuilder getMethodBuilder = typeBuilder.DefineMethod(
"Get" + propertyName,
MethodAttributes.Public,
propertyType,
new Type[] { }
);
ILGenerator getMethodIL = getMethodBuilder.GetILGenerator();
getMethodIL.Emit(OpCodes.Ldarg_0);
getMethodIL.Emit(OpCodes.Ldfld, fieldBuilder);
getMethodIL.Emit(OpCodes.Ret);
// Now, we'll define the behavior of the "set" accessor for the property.
MethodBuilder setMethodBuilder = typeBuilder.DefineMethod(
"Set" + propertyName,
MethodAttributes.Public,
null,
new Type[] { propertyType }
);
ILGenerator custNameSetIL = setMethodBuilder.GetILGenerator();
custNameSetIL.Emit(OpCodes.Ldarg_0);
custNameSetIL.Emit(OpCodes.Ldarg_1);
custNameSetIL.Emit(OpCodes.Stfld, fieldBuilder);
custNameSetIL.Emit(OpCodes.Ret);
// Last, we must map the two methods created above to our PropertyBuilder to
// their corresponding behaviors, "get" and "set" respectively.
propertyBuilder.SetGetMethod(getMethodBuilder);
propertyBuilder.SetSetMethod(setMethodBuilder);
}
//MethodBuilder toStringMethodBuilder = typeBuilder.DefineMethod(
// "ToString",
// MethodAttributes.Public,
// typeof(string),
// new Type[] { }
//);
return typeBuilder.CreateType();
}
public static Boolean IsAnonymousType(this Type type)
{
Boolean hasCompilerGeneratedAttribute = type.GetCustomAttributes(
typeof(CompilerGeneratedAttribute), false).Count() > 0;
Boolean nameContainsAnonymousType =
type.FullName.Contains("AnonymousType");
Boolean isAnonymousType = hasCompilerGeneratedAttribute && nameContainsAnonymousType;
return isAnonymousType;
}
}

This works for me, but I'm sure it could be given some love and attention and look better. It does not include your type-check but that would be rather trivial to add. So while this is not a perfect answer, I hope it can get you closer to a solution.
Subsequent calls to DynamicIntoExpando(...) will keep appending and overwriting new and existing values to the existing Source structure. You can call it as many times as you need to. The function MergeDynamic() illustrates how two dynamics are merged into one ExpandoObject.
The code basically iterates over the dynamic value, checks the type, and merge appropriately and recursively to any depth.
I wrapped it in a helper class for my own purposes.
using System.Dynamic; // For ExpandoObject
...
public static class DynamicHelper
{
// We expect inputs to be of type IDictionary
public static ExpandoObject MergeDynamic(dynamic Source, dynamic Additional)
{
ExpandoObject Result = new ExpandoObject();
// First copy 'source' to Result
DynamicIntoExpando(Result, Source);
// Then copy additional fields, boldy overwriting the source as needed
DynamicIntoExpando(Result, Additional);
// Done
return Result;
}
public static void DynamicIntoExpando(ExpandoObject Result, dynamic Source, string Key = null)
{
// Cast it for ease of use.
var R = Result as IDictionary<string, dynamic>;
if (Source is IDictionary<string, dynamic>)
{
var S = Source as IDictionary<string, dynamic>;
ExpandoObject NewDict = new ExpandoObject();
if (Key == null)
{
NewDict = Result;
}
else if (R.ContainsKey(Key))
{
// Already exists, overwrite
NewDict = R[Key];
}
var ND = NewDict as IDictionary<string, dynamic>;
foreach (string key in S.Keys)
{
ExpandoObject NewDictEntry = new ExpandoObject();
var NDE = NewDictEntry as IDictionary<string, dynamic>;
if (ND.ContainsKey(key))
{
NDE[key] = ND[key];
}
else if (R.ContainsKey(key))
{
NDE[key] = R[key];
}
DynamicIntoExpando(NewDictEntry, S[key], key);
if(!R.ContainsKey(key)) {
ND[key] = ((IDictionary<string, dynamic>)NewDictEntry)[key];
}
}
if (Key == null)
{
R = NewDict;
}
else if (!R.ContainsKey(Key))
{
R.Add(Key, NewDict);
}
}
else if (Source is IList<dynamic>)
{
var S = Source as IList<dynamic>;
List<ExpandoObject> NewList = new List<ExpandoObject>();
if (Key != null && R.ContainsKey(Key))
{
// Already exists, overwrite
NewList = (List<ExpandoObject>)R[Key];
}
foreach (dynamic D in S)
{
ExpandoObject ListEntry = new ExpandoObject();
DynamicIntoExpando(ListEntry, D);
// in this case we have to compare the ListEntry to existing entries and on
NewList.Add(ListEntry);
}
if (Key != null && !R.ContainsKey(Key))
{
R[Key] = NewList.Distinct().ToList();
}
}
else
{
R[Key] = Source;
}
}
}