Develop Reference

MongoDB Serialization C# - Adding Additional Encrypted Field Properties

I am trying to write a MongoDb serializer in c# that will allow me to decorate properties via a [Encrypt()] attribute and then at runtime it would allow me to generate an additional property called PropertyName_Encrypted which would contain the encrypted value.
On deserialization, the encrypted property value would be set in the parent property so that the default GET for the property always returns the encrypted value. Users will then call an optional Decrypt() method on the object to get decrypted values.
In doing so, I'm running into some interesting challenges:
How do I add Additional properties to the document when I am serializing current Element? How do I get the current element's name?
Is there a way I can read a specific property from the document/object? For e.g. say I want to pass a symmetric encryption key and read that to encrypt the data while serializing the current element? Is there any way I can do that?
Here are things I have done so far:
I've built an Encrypt Attribute as follows:
[AttributeUsage(AttributeTargets.Property)]
public class EncryptAttribute : Attribute
{
private readonly EncryptedFieldType _fieldType;
private readonly bool _tokenizeDisplay;
private readonly string _encryptedFieldName;
/// <summary>
///
/// </summary>
/// <param name="fieldType">The field type to encrypt. Useful if display needs to show some formatting. If no formatting is necessary, simply set to "Other".</param>
/// <param name="tokenizeDisplay">If set to true, will persist the tokenized value in the original field for display purposes.</param>
/// <param name="encryptedFieldName">Optional. If set, will save the encrypted value in the field name specified. By default all encrypted field values are stored in the corresponding _Encrypted field name. So EmailAddress field if encrypted, would have value under EmailAddress_Encrypted.</param>
public EncryptAttribute(EncryptedFieldType fieldType, bool tokenizeDisplay, string encryptedFieldName = "")
{
_fieldType = fieldType;
_tokenizeDisplay = tokenizeDisplay;
_encryptedFieldName = encryptedFieldName;
}
}
I read this Attribute on Startup and add an Encryption Serializer to the properties that are decorated using this attribute. The code that does that is like so:
var assemblies = AppDomain.CurrentDomain.GetAssemblies()
.Where(x => x.FullName.StartsWith("MongoCustomSerializer"))
.ToList();
var mapper = new Mapper();
foreach (var assembly in assemblies)
{
mapper.Map(assembly);
}
The mapper simply checks which properties in the document have the Encrypt attribute to add the serializer:
public sealed class Mapper
{
public void Map(Assembly assembly)
{
var encryptableTypes = assembly.GetTypes().Where(p =>
typeof(IEncryptable).IsAssignableFrom(p) && p.IsClass && !p.IsInterface && !p.IsValueType &&
!p.IsAbstract).ToList();
if (encryptableTypes.Any())
{
foreach (var encryptableType in encryptableTypes)
{
Map(encryptableType);
}
}
}
private void Map(Type documentType)
{
var properties =
documentType.GetProperties(BindingFlags.Public | BindingFlags.Instance);
if (properties.Length <= 0)
{
return;
}
foreach (var property in properties)
{
RegisterEncrpytionSerializer(property, typeof(EncryptAttribute), documentType);
}
}
private void RegisterEncrpytionSerializer(PropertyInfo property, Type encryptAttributeType, Type documentType)
{
var encryptAttributes = property.GetCustomAttributes(encryptAttributeType, false).ToList();
if (!encryptAttributes.Any()) return;
var memberMap = BsonClassMap.LookupClassMap(documentType).GetMemberMap(property.Name);
memberMap?.SetSerializer(new EncryptionSerializer());
}
}
In my unit tests, I'm getting an error stating that the Bson Class Map is already frozen. Even if I were to figure out a way to bypass that, how would this EncryptionSerializer class work to where I could write an additional property?
Would love to see if someone can assist!
UPDATE 1 - I was able to get the FREEZE error taken care of. It would appear that the LookupClassMap freezes the Member and Class Map info.
This change from the link allows me to take care of that issue:
private void RegisterEncrpytionSerializer(PropertyInfo property, Type encryptAttributeType, Type documentType)
{
var encryptAttributes = property.GetCustomAttributes(encryptAttributeType, false).ToList();
if (!encryptAttributes.Any()) return;
var classMapDefinition = typeof(BsonClassMap<>);
var classMapType = classMapDefinition.MakeGenericType(documentType);
var classMap = (BsonClassMap)Activator.CreateInstance(classMapType);
classMap.AutoMap();
var memberMap = classMap.GetMemberMap(property.Name);
memberMap?.SetSerializer(new KeyVaultEncryptionSerializer(memberMap.ElementName));
}

Are you using a service for saving/retrieving your items that actually call the DB?
I believe you should move the responsibility for writing/reading encrypted values to the calling service (i.e a repository implementation) instead of the BsonSerializer.
It would make sense to me that encryption/decryption is part of the persistence layer and something not handled in the application when needed.
Your implementation targets only the specified property you want to serialize. It doesn't make sense that it creates another property.
A second thought is that your suggested approach with properties that change value based on Decrypt() probably isn't a good idea since it makes your code unpredictable and hard to read. Make your properties dead simple.
What extra security in your code does it really give you if you can decrypt properties by just calling a method anyway?
If you still need to have a Decrypt() would suggest that you create methods for decrypting that return the decrypted value like GetUnencryptedCode() etc, it could just as well be an extension method but still not a readable property.
You should also be looking into using SecureString depending on your use case.

Extending linq to sharepoint for Publishing HTML fields

I've created a partial class to extend the default spmetal class to handle publishing html fields. As outlined here:
Extending the Object-Relational Mapping
Snippet from public partial class RelatedLinksItem : Item, ICustomMapping:
/// <summary>
/// Read only data is retrieved in this method for each extended SPMetal field
/// Used to Read - CRUD operation performed by SPMetal
/// </summary>
/// <param name="listItem"></param>
[CustomMapping(Columns = new string[] { CONTENT_FIELDtesthtml, CONTENT_FIELDLink })]
public void MapFrom(object listItem)
{
SPListItem item = (SPListItem)listItem;
// link
this.ContentLink = item[CONTENT_FIELDLink] as LinkFieldValue;
// html (does NOT work)
HtmlField html = item[CONTENT_FIELDtesthtml] as HtmlField; // this returns null
// html (does work)
HtmlField html2 = (HtmlField)item.Fields.GetFieldByInternalName(CONTENT_FIELDtesthtml); // this returns object
this.Contenttesthtml = html2;
this.TestHtml = html2.GetFieldValueAsText(item[CONTENT_FIELDtesthtml]); // set property for rendering html
}
Snippet from "webpart":
protected override void CreateChildControls()
{
using (OrganisationalPoliciesDataContext context = new OrganisationalPoliciesDataContext(SPContext.Current.Web.Url))
{
var results = from links in context.RelatedLinks
select links;
foreach (var link in results)
{
// render link
Controls.Add(new LiteralControl(string.Format("<p>Link: {0}</p>", link.ContentLink)));
// render html
Controls.Add(new LiteralControl(string.Format("<p>HTML: {0}</p>", link.TestHtml)));
}
}
}
Two questions:
Why does HtmlField html = item[CONTENT_FIELDtesthtml] as HtmlField; return null, but the item.Fields.GetFieldByInternalName works correctly?
Is there a way to use the GetFieldValueAsText method from within
the webpart or is the approach of storing the value in a custom
property for accessing later acceptable?

You are casting the field value of item[CONTENT_FIELDtesthtml] to the type HtmlField. But HtmlField represents the type of the field and not the type of the field value. Thus HtmlField html will be assigned with null. Check this MSDN page for a reference of all publishing field types and value types.
I am not sure what the field value type of a HtmlField is. Probably just string.
So you should be safe to convert it to string:
string html = Convert.ToString(item[CONTENT_FIELDtesthtml]);
I think storing the value in a property is the way to go. This way you achieve a separation of data layer and presentation layer.

Entity framework 4 CRUD creating errors

I have 3 related tables in my database.
Farm ----> FarmCrops <----- Crops
I'm trying to update the a farm entity with a collection of crops but am running into problems. I've been working on this with no success for hours now so any help would be greatly appreciated.
The error I'm receiving is this:
The object cannot be attached because
it is already in the object context.
An object can only be reattached when
it is in an unchanged state.
My update logic is as follows (my apologies for the large amount of code. I'd just like to be as clear as possible):
bool isNew = false;
Farm farm;
// Insert or update logic.
if (viewModel.Farm.FarmId.Equals(Guid.Empty))
{
farm = new Farm
{
FarmId = Guid.NewGuid(),
RatingSum = 3,
RatingVotes = 1
};
isNew = true;
}
else
{
farm = this.ReadWriteSession
.Single<Farm>(x => x.FarmId == viewModel.Farm.FarmId);
}
// Edit/Add the properties.
farm.Name = viewModel.Farm.Name;
farm.Owner = viewModel.Farm.Owner;
farm.Address = viewModel.Farm.Address;
farm.City = viewModel.Farm.City;
farm.Zip = viewModel.Farm.Zip;
farm.WebAddress = viewModel.Farm.WebAddress;
farm.PhoneNumber = viewModel.Farm.PhoneNumber;
farm.Hostel = viewModel.Farm.Hostel;
farm.Details = viewModel.Farm.Details;
farm.Latitude = viewModel.Farm.Latitude;
farm.Longitude = viewModel.Farm.Longitude;
farm.Weather = viewModel.Farm.Weather;
// Add or update the crops.
string[] cropIds = Request.Form["crop-token-input"].Split(',');
List<Crop> allCrops = this.ReadWriteSession.All<Crop>().ToList();
if (!isNew)
{
// Remove all previous crop/farm relationships.
farm.Crops.Clear();
}
// Loop through and add any crops.
foreach (Crop crop in allCrops)
{
foreach (string id in cropIds)
{
Guid guid = Guid.Parse(id);
if (crop.CropId == guid)
{
farm.Crops.Add(crop);
}
}
}
if (isNew)
{
this.ReadWriteSession.Add<Farm>(farm);
}
else
{
this.ReadWriteSession.Update<Farm>(farm);
}
this.ReadWriteSession.CommitChanges();
My update code within the ReadWriteSession is simple enough (GetSetName<T> just returns the types name from it's PropertyInfo.):
/// <summary>
/// Updates an instance of the specified type.
/// </summary>
/// <param name="item">The instance of the given type to add.</param>
/// <typeparam name="T">The type of entity for which to provide the method.</typeparam>
public void Update<T>(T item) where T : class, new()
{
this.context.AttachTo(this.GetSetName<T>(), item);
this.context.ObjectStateManager.ChangeObjectState(item, EntityState.Modified);
}

You are adding existing Crop objects (from the allCrops list) to the new Farm. When you connect a new entity to an existing one, the new entity automatically gets attached to the context. Therefore you get the error when you try to attach the Farm to the context the second time.
The Add<Farm>(farm) statement in your code is not even necessary to connect the Farm to the context, and if you have an existing Farm that is loaded from the context, it is already attached to the context.
The whole of your if (isNew) statement is unnecessary. Entity framework tracks object state itself, so you don't need to set the modified state.

you don't have to attach the "farm" object at the end, because it's already attached as modified when you change one of its properties. try removing the else statement at the end:
if (isNew)
{
this.ReadWriteSession.Add<Farm>(farm);
}
Hope this helps :)

The problem is in your update method. You can't attach the Farm instance because you have loaded it from the same context so it is already attached and you don't need to call your Update at all because changes to attached objects are tracked automatically.

Entity Framework: Set back to default value

I'm trying to update an entity using a stub. This works fine for changing records, unless I try to set the value back to the default value forr the column. Eg: If the default value is 0, I can change to and from any value except zero, but the changes aren't saved if I try to set it back to zero. This is the code I'm using:
var package = new Package() {
PackageID = 4
};
...
public static void EditPackage(Package package) {
using(var context = new ShopEntities()) {
context.Packages.MergeOption = MergeOption.NoTracking;
var existing = new Package() {
PackageID = package.PackageID
};
context.AttachTo("Packages", existing);
context.ApplyPropertyChanges("ShopEntities.Packages", package);
context.AcceptAllChanges(); // doesn't make a difference
System.Diagnostics.Debug.WriteLine((package.DateSent.HasValue ? package.DateSent.Value.ToString("D") : "none") + "\t\t" + package.IsReceived);
context.SaveChanges();
}
}
In the example above, DateSent's default value is null (It's a DateTime?), and I can also set it to any value other than null, and the debug line confirms the correct properties are set, they're just not saved. I think I must be missing something.
Thanks for any help.

Turns out what I needed to do was manually mark each property in the new item as modified.
/// <summary>
/// Sets all properties on an object to modified.
/// </summary>
/// <param name="context">The context.</param>
/// <param name="entity">The entity.</param>
private static void SetAllPropertiesModified(ObjectContext context, object entity) {
var stateEntry = context.ObjectStateManager.GetObjectStateEntry(entity);
// Retrieve all the property names of the entity
var propertyNames = stateEntry.CurrentValues.DataRecordInfo.FieldMetadata.Select(fm => fm.FieldType.Name);
foreach(var propertyName in propertyNames) {// Set each property as modified
stateEntry.SetModifiedProperty(propertyName);
}
}

You are creating a new package (with the id of an existing package), which you are calling "existing". You are then attaching it as if it was an existing package. You should load this package from the database and then attach it.

Dynamics CRM - access property within a workflow on newly created entity

I'm creating a Dynamics CRM workflow assembly to be executed when a new Note is created on another record of any type. I need to be able to access a property Prop1 on that newly created Note entity to accomplish other tasks.
Previously I've only accessed values that were input from a field or from the user, but never on a property of a newly created entity. Any guidance would be appreciated.
UPDATE:
This is regarding CRM 4.0.
More information while I wait:
Ultimately, this workflow assembly will create an email that contains a link to the parent entity of the newly created Note record. The property I need to get is the AnnotationId. Once the Note record is created, I will be retrieving the ObjectId and ObjectTypeCode based on the AnnotationId of the newly created Note.
(In case you were curious)

Ok so if your using 4.0 custom workflows and not 3.0 callouts, you should add a workflow assembly, and use the Context service and executing context of your workflow to pull the values from the new note.
See the example below on how to access a record using the context service and the ID of your current context of execution (that should be your note)
/// <summary>
/// The Execute method is called by the workflow runtime to execute an activity.
/// </summary>
/// <param name="executionContext"> The context for the activity</param>
/// <returns></returns>
protected override ActivityExecutionStatus Execute(ActivityExecutionContext executionContext)
{
// Get the context service.
IContextService contextService = (IContextService)executionContext.GetService(typeof(IContextService));
IWorkflowContext context = contextService.Context;
// Use the context service to create an instance of CrmService.
ICrmService crmService = context.CreateCrmService(true);
BusinessEntity newNote = GetNote(crmService, context.PrimaryEntityId);
string noteAttrib;
noteAttrib = newNote.Properties.Contains("AnnotationId") ? ((Lookup)newNote.Properties["annotationid"]).name.ToString() : null;
return ActivityExecutionStatus.Closed;
}
GetNotes method would be a standard query for notes by Id through a CRM service call,
here is an example slightly modified from MSDN to return a note:
private BusinessEntity getNote(ICrmService service, guid noteid)
{
// Create the column set object that indicates the fields to be retrieved.
ColumnSet cols = new ColumnSet();
// Set the columns to retrieve, you can use allColumns but its good practice to specify:
cols.Attributes = new string [] {"name"};
// Create the target object for the request.
TargetRetrieveAnnotation target = new TargetRetrieveAnnotation();
// Set the properties of the target object.
// EntityId is the GUID of the record being retrieved.
target.EntityId = noteid;
// Create the request object.
RetrieveRequest retrieve = new RetrieveRequest();
// Set the properties of the request object.
retrieve.Target = target;
retrieve.ColumnSet = cols;
// Execute the request.
RetrieveResponse retrieved = (RetrieveResponse)service.Execute(retrieve);
return RetrieveResponse;
}