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Unit Test mongoDb with .net core

I am trying to write down unit test for my repository which is interacting with MongoDb but facing a problem/exception in mocking the objects. This is what I have tried so far;
This is how my class looks like i.e. I have create a repository class and extend it from interface;
public class UserManagementRepository : IUserManagementRepository
{
private readonly IMongoCollection<UserModel> _users;
public UserManagementRepository(IDatabaseSettings dbSettings, IApplicationSettings applicationSettings, IMongoClient mongoClient)
{
IMongoDatabase database = mongoClient.GetDatabase(dbSettings.DatabaseName);
_users = database.GetCollection<UserModel>(applicationSettings.UserCollectionName);
}
public async Task<GeneralResponse> Get(string id)
{
GeneralResponse response = new GeneralResponse();
try
{
IAsyncCursor<UserModel> userModel = await _users.FindAsync(user => user.Id == id);
if (userModel != null)
{
response.Message = "User exists!";
response.Data = userModel.FirstOrDefault();
response.ResponseCode = ResponseCode.Success;
}
else
{
response.Message = $"User with Id: {id} not found!";
response.ResponseCode = ResponseCode.Success;
}
}
catch (Exception ex)
{
response.Message = "Failure";
response.ResponseCode = ResponseCode.Error;
}
return response;
}
}
This is how my Test class look like
public class UserManagmentRepositoryTests
{
private Mock<IDatabaseSettings> _mockDbSettings;
private Mock<IApplicationSettings> _mockApplicationSettings;
private Mock<IMongoClient> _mockClient;
public UserManagmentRepositoryTests()
{
_mockDbSettings = new Mock<IDatabaseSettings>();
_mockApplicationSettings = new Mock<IApplicationSettings>();
_mockClient = new Mock<IMongoClient>();
}
[Fact]
public async Task GetUserWithId_Test()
{
// Arrange
var repo = new Mock<IUserManagementRepository>();
IDatabaseSettings dbSettings = new DatabaseSettings()
{
ConnectionString = "mongodb:connectionstring",
DatabaseName = "dbname"
};
_mockDbSettings.Setup(x => x).Returns(dbSettings);
IApplicationSettings applicationSettings = new ApplicationSettings() { UserCollectionName = "users" };
_mockApplicationSettings.Setup(app => applicationSettings).Returns(applicationSettings);
MongoClientSettings clientSettings = MongoClientSettings.FromConnectionString(dbSettings.ConnectionString);
MongoClient client = new MongoClient(clientSettings);
_mockClient.Setup(c => client);
var ctr = new UserManagementRepository(_mockDbSettings.Object, _mockApplicationSettings.Object, _mockClient.Object);
// Act
var result = ctr.Get("132");
// Assert
//result.StatusCode.Should().NotBeNull();
}
}
I get an exception on every setup

You are trying to use ApplicationSettings as an expression. The setup method expects you to provide an expression for when to activate the mocked override.
In your case just get rid of the Mock<IApplicationSettings> altogether and mock all the objects you need to call any methods on:
[Fact]
public async Task GetUserWithId_Test()
{
// Arrange
var userModel = new UserModel() { Id = "123" };
var mockCursor = new Mock<IAsyncCursor<UserModel>>();
mockCursor
.Setup(c => c.FirstOrDefault())
.Returns(userModel);
var mockCollection = new Mock<IMongoCollection<UserModel>>();
Predicate<UserModel> filter = u => u.Id == userModel.Id;
mockCollection
.Setup(c => c.FindAsync(filter))
.ReturnsAsync(mockCursor.Object);
var mockDb = new Mock<IMongoDatabase>();
mockDb
.Setup(db => db.GetCollection<UserModel>(It.IsAny<string>()))
.Returns(mockCollection.Object);
_mockClient
.Setup(c => c.GetDatabase(It.IsAny<string>()))
.Returns(mockDb.Object)
var ctr = new UserManagementRepository(new(), new(), _mockClient.Object);
// Act
var result = ctr.Get("132");
// Assert
result.StatusCode.Should().Be(ResponseCode.Success);
result.Message.Should().Be("User exists!");
result.Data.Should().Be(userModel);
}
Hope this helps a little 🙂

To use your ApplicationSettings as mocked ApplicationSettings, you must use an expression in the setup method.
Instead of:
IApplicationSettings applicationSettings = new ApplicationSettings() { UserCollectionName = "users" };
_mockApplicationSettings.Setup(app => applicationSettings).Returns(applicationSettings);
Use e.g. this:
IApplicationSettings applicationSettings = new ApplicationSettings() { UserCollectionName= "users" };
_mockApplicationSettings.Setup(app => app.UserCollectionName).Returns(applicationSettings.UserCollectionName);
Edit: Complete Example
private Mock<IDatabaseSettings> _mockDbSettings;
private Mock<IApplicationSettings> _mockApplicationSettings;
private Mock<IMongoClient> _mockClient;
public UserManagmentRepositoryTests()
{
_mockDbSettings = new Mock<IDatabaseSettings>();
_mockApplicationSettings = new Mock<IApplicationSettings>();
_mockClient = new Mock<IMongoClient>();
}
[Fact]
public async Task GetUserWithId_Test()
{
// Arrange
var repo = new Mock<IUserManagementRepository>();
IDatabaseSettings dbSettings = new DatabaseSettings()
{
ConnectionString = "mongodb:connection",
DatabaseName = "dbname"
};
_mockDbSettings.Setup(x => x.ConnectionString).Returns(dbSettings.ConnectionString);
_mockDbSettings.Setup(x => x.DatabaseName).Returns(dbSettings.DatabaseName);
IApplicationSettings applicationSettings = new ApplicationSettings() { UserCollectionName = "users" };
_mockApplicationSettings.Setup(app => app.UserCollectionName).Returns(applicationSettings.UserCollectionName);
MongoClientSettings clientSettings = MongoClientSettings.FromConnectionString(dbSettings.ConnectionString);
MongoClient client = new MongoClient(clientSettings);
_mockClient.Setup(c => c.GetDatabase(It.IsAny<string>(), It.IsAny<MongoDatabaseSettings>()))
.Returns <string, MongoDatabaseSettings>((name, settings) => client.GetDatabase(name, settings));
var ctr = new UserManagementRepository(_mockDbSettings.Object, _mockApplicationSettings.Object, _mockClient.Object);
// Act
var result = await ctr.Get("132");
// Assert
result.ResponseCode.Should().NotBe(ResponseCode.Error);
}

I see no reason mocking IApplicationSettings and IDatabaseSettings you should go with :
public class UserManagmentRepositoryTests
{
private Mock<IMongoClient> _mockClient;
public UserManagmentRepositoryTests()
{
_mockClient = new Mock<IMongoClient>();
}
[Fact]
public async Task GetUserWithId_Test()
{
// Arrange
var repo = new Mock<IUserManagementRepository>();
IDatabaseSettings dbSettings = new DatabaseSettings()
{
ConnectionString = "mongodb:connectionstring",
DatabaseName = "dbname"
};
IApplicationSettings applicationSettings = new ApplicationSettings() { UserCollectionName = "users" };
MongoClientSettings clientSettings = MongoClientSettings.FromConnectionString(dbSettings.ConnectionString);
MongoClient client = new MongoClient(clientSettings);
_mockClient.Setup(c => client);
var ctr = new UserManagementRepository(dbSettings, applicationSettings, _mockClient.Object);
// Act
var result = ctr.Get("132");
// Assert
//result.StatusCode.Should().NotBeNull();
}
}

How to invoke Method immediately after instantiating

I have a controller that calls an api to get a list of Positions and Employees . First it puts the api results into a model class - IDMSElements (1). Then the controller takes the IDMSElements object and converts it to a PositionSlots object (2). Then the PositionSlots object needs to be updated with additional data from a database (3). So in simplified version of my controller I have:
(1) IDMSElements elements = getslots.CopyDocToElements(doc);
(2) PositionSlots myslots = (PositionSlots)elements;
(3) myslots.UpdateDetails(db);
I am concerned about the myslots.UpdateDetails(db) because additional code in the controller depends on UpdateDetails having been run. I would like the UpdateDetails to be run by default when creating the PositionSlots object. But I think multiple database calls in a constructor probably should not be done. How can I make it so the UpdateDetails is automatically invoked after the PositionSlots object is instantiated?
Thank you very much!
Controller:
[Authorize]
public class PSListController : Controller
{
private static readonly log4net.ILog _logger = log4net.LogManager.GetLogger(System.Reflection.MethodBase.GetCurrentMethod().DeclaringType);
private PositionControlContext db = new PositionControlContext();
private GetPositionSlots getslots = new GetPositionSlots();
...
public async Task<ActionResult> ByCostCenter(int costCenter)
{
string ssapiuri = getslots.BuildAPIuri($"/current/?UDAKunit={costCenter.ToString()}");
_logger.Debug($"{ssapiuri.ToString()}");
Stopwatch stopWatch = new Stopwatch();
stopWatch.Start();
HttpResponseMessage result = await getslots.GetDataFromIDMSapi(ssapiuri);
stopWatch.Stop();
_logger.Debug($"Response received. Milliseconds elapsed: {stopWatch.Elapsed.TotalMilliseconds.ToString()}");
if (result.StatusCode != HttpStatusCode.OK)
{
_logger.Debug("Error retrieving data from API. Milliseconds elapsed: " + stopWatch.Elapsed.TotalMilliseconds.ToString());
throw new HttpException(404, "NotFound");
}
stopWatch.Restart();
XDocument doc = XDocument.Load(result.Content.ReadAsStreamAsync().Result);
stopWatch.Stop();
_logger.Debug($"API result loaded into XDocument. Milliseconds elapsed: {stopWatch.Elapsed.TotalMilliseconds.ToString()}\n");
_logger.Debug(doc.ToString());
IDMSElements elements = getslots.CopyDocToElements(doc);
XMLDocStats docstats = new XMLDocStats(elements);
_logger.Debug(docstats.ToString());
PositionSlots myslots = (PositionSlots)elements;
myslots.UpdateDetails(db);
//because this is dependent upon UpdatePositionSlotId having been run
//need to find a way to force UpdateDetails to run other than calling from Controller??
var mainPositionSlots = myslots.PositionsCurrentAndActive;
var budget = db.Database.SqlQuery<Budget>("GetBudgetForCostCenter #costCenter = {0}", costCenter);
List<Budget> budgetRows = budget.ToList();
JobClassGroups jobClassGroups = new JobClassGroups(mainPositionSlots, budgetRows);
Department dept = db.Departments.AsNoTracking().Where(d => d.CostCenter == costCenter).SingleOrDefault();
var model = new ByCostCenter_vm(dept, myslots, jobClassGroups);
ViewBag.stats = docstats.ToString();
return View("ByCostCenter", model);
}
protected override void Dispose(bool disposing)
{
if (disposing)
{
db.Dispose();
}
base.Dispose(disposing);
}
}
IDMSElements Class:
public class IDMSElements
{
//properties
public ICollection<IDMSElementData> Elements { get; set; }
//constructors
public IDMSElements() { }
public IDMSElements(ICollection<IDMSElementData> elList)
{
Elements = elList;
}
//methods
public static explicit operator PositionSlots(IDMSElements obj)
{
//this is assuming we are looking at a list of elements
//that contains the "current" positions
Dictionary<string, PositionSlotDetail> positionSlots = new Dictionary<string, PositionSlotDetail>();
var sorted = from element in obj.Elements
orderby element.positionNbr
select element;
foreach (IDMSElementData el in sorted)
{
if (!positionSlots.ContainsKey(el.positionNbr))
{
PositionSlotDetail psd = new PositionSlotDetail
{
CostCenter = Int32.Parse(el.UDAKunit),
CostCenter_7Char = el.UDAKunit,
PositionNumber = el.positionNbr,
PositionSlotId = 0,
JobClassId = el.jobClassCode.Replace("-", ""),
JobClassFullDisplayCd = string.Empty,
JobTitle = string.Empty,
SalaryGradeCd = string.Empty,
FTE_percent = el.FTEpercent / 100,
EmployeeId = el.employeeID,
EmployeeName = String.Empty,
PositionEffDate = el.positionEffDate,
PositionEffDateNext = el.positionEffDateNext,
PositionBeginDate = el.positionBeginDate,
PositionEndDate = el.positionEndDate,
DirectLeaderID = string.Empty,
DirectLeaderName = string.Empty,
DirectLeaderNetID = string.Empty,
FLSAstatusCode = el.FLSAstatusCode,
FLSAstatusDesc = el.FLSAstatusDesc,
EmploymentTypeCode = el.employmentTypeCode,
EmploymentTypeDesc = el.employmentTypeDesc,
IsOverloaded = false,
};
positionSlots[el.positionNbr] = psd;
}
Assignment newAssignment = new Assignment
{
PvID = el.employeeID,
AssignBeginDate = el.assignBeginDate,
AssignEndDate = el.assignEndDate,
AssignEffDate = el.assignEffDate,
AssignEffDateNext = el.assignEffDateNext,
};
PositionSlotDetail thePSD = positionSlots[el.positionNbr];
thePSD.Assignments.Add(newAssignment);
if (thePSD.Assignments.Any(assignment => Regex.IsMatch(assignment.PvID, #"^\d+$")))
{
thePSD.Status = "FILLED";
if (thePSD.Assignments.Where(assignment => Regex.IsMatch(assignment.PvID, #"^\d+$")).Count() > 1)
{
thePSD.IsOverloaded = true;
}
}
else
{
thePSD.Status = "VACANT";
}
}
var output = new PositionSlots(positionSlots.Values.ToList());
return output;
}
...
}
PositionSlots class:
public class PositionSlots
{
//Constructor
public PositionSlots(ICollection<PositionSlotDetail> pslist)
{
Positions = pslist;
}
//properites
public ICollection<PositionSlotDetail> Positions { get; }
private bool DetailsUpdated { get; set; } = false;
public IEnumerable<PositionSlotDetail> PositionsCurrentAndActive
{
get
{
return from position in Positions
where position.PositionSlotId > 0 && position.PositionEndDate >= DateTime.Today
select position;
}
}
public IEnumerable<PositionSlotDetail> PositionsNotFoundInPositionControl
{
get
{
return from position in Positions
where position.PositionSlotId == 0
select position;
}
}
public IEnumerable<PositionSlotDetail> PositionsClosed
{
get
{
return from psd in Positions
where psd.PositionEndDate < DateTime.Today
&& psd.PositionSlotId > 0
select psd;
}
}
public decimal ActualFTETotal
{
get
{
return (from position in PositionsCurrentAndActive
from assignment in position.Assignments
where position.Assignments.Count() >= 1 && (!assignment.PvID.Equals("VACANT"))
select position.FTE_percent).Sum();
}
}
public int FilledTotal
{
get
{
return PositionsCurrentAndActive.Where(x => x.Status == "FILLED").Count();
}
}
public int VacantTotal
{
get
{
return PositionsCurrentAndActive.Where(x => x.Status == "VACANT").Count();
}
}
public int OverloadedTotal
{
get
{
return PositionsCurrentAndActive.Where(x => x.IsOverloaded).Count();
}
}
//methods
public void UpdateDetails(PositionControlContext db)
{
if (!DetailsUpdated)
{
UpdateJobClassificationInfo(db);
UpdateEmployeeName(db);
UpdatePositionSlotId(db); //if not found, PositionSlotId = 0
//UpdateIsBudgeted(db);
UpdateDirectLeader(db);
DetailsUpdated = true;
}
else
{
return;
}
}
private void UpdateJobClassificationInfo(PositionControlContext db)
{
string[] jobClassIds = (from x in Positions select x.JobClassId).Distinct().ToArray();
var JobClassList = (from jc in db.JobClassifications where jobClassIds.Contains(jc.JobClassId) select jc).ToDictionary(jc => jc.JobClassId, jc => jc, StringComparer.OrdinalIgnoreCase);
foreach (PositionSlotDetail psd in Positions)
{
if (!string.IsNullOrWhiteSpace(psd.JobClassId) && !psd.JobClassId.Equals("MISSING"))
{
JobClassification jobClassification;
if (JobClassList.TryGetValue(psd.JobClassId, out jobClassification))
{
psd.JobClassFullDisplayCd = jobClassification.JobClassFullDisplayCd;
psd.JobTitle = jobClassification.JobTitle;
psd.SalaryGradeCd = jobClassification.SalaryGradeCd;
}
else
{
psd.JobClassFullDisplayCd = ($"{psd.JobClassId} not found in view V_JobClassifications.");
psd.JobTitle = ($"{psd.JobClassId} not found in view V_JobClassifications.");
psd.SalaryGradeCd = "--";
}
}
else
{
psd.JobClassFullDisplayCd = "MISSING";
psd.JobTitle = "MISSING";
}
}
return;
}
private void UpdateEmployeeName(PositionControlContext db)
{
string[] empIdsStr = (from position in Positions
from assignment in position.Assignments
where (!assignment.PvID.Equals("VACANT"))
select assignment.PvID).Distinct().ToArray();
// Positions.SelectMany(x => x.Assignments).SelectMany(x => x.PvID).ToArray();
//string[] empIdsStr = (from x in Positions where (!x.EmployeeId.Contains("VACANT")) select x.EmployeeId).Distinct().ToArray();
//int[] empIdsInt = Array.ConvertAll(empIdsStr, int.Parse);
var EmployeeList = (from emp in db.IdAM_personLU where empIdsStr.Contains(emp.pvID) select emp).ToDictionary(emp => emp.pvID,
emp => emp.EmployeeFullName, StringComparer.OrdinalIgnoreCase);
EmployeeList["VACANT"] = "VACANT";
foreach (PositionSlotDetail psd in Positions)
{
string empName;
if (EmployeeList.TryGetValue(psd.EmployeeId, out empName))
{
psd.EmployeeName = empName;
}
else
{
psd.EmployeeName = ($"{psd.EmployeeId} not found in Employee table.");
}
foreach (Assignment emp in psd.Assignments)
{
string empName2;
if (EmployeeList.TryGetValue(emp.PvID, out empName2))
{
emp.EmpDisplayName = empName2;
}
else
{
emp.EmpDisplayName = ($"{psd.EmployeeId} not found in Employee table.");
}
}
}
return;
}
private void UpdateDirectLeader(PositionControlContext db)
{
string[] empIdsStr = (from x in Positions where (!x.EmployeeId.Contains("VACANT")) select x.EmployeeId).Distinct().ToArray();
//int[] empIdsInt = Array.ConvertAll(empIdsStr, int.Parse);
Dictionary<string, IdAM_arborLU> DirectLeader = new Dictionary<string, IdAM_arborLU>();
var EmployeeDirectLeaderList = (from emp in db.IdAM_arborLU where empIdsStr.Contains(emp.emp_pvID) select emp).ToDictionary(emp => emp.emp_pvID,
emp => emp, StringComparer.OrdinalIgnoreCase);
foreach (PositionSlotDetail psd in Positions)
{
if (psd.EmployeeId != "VACANT") //will just leave DirectLeaderId and DirectLeaderName as string.Empty
{
IdAM_arborLU supervisor;
if (EmployeeDirectLeaderList.TryGetValue(psd.EmployeeId, out supervisor))
{
psd.DirectLeaderName = supervisor.sup_name;
psd.DirectLeaderID = supervisor.sup_pvID;
psd.DirectLeaderNetID = supervisor.sup_netID;
}
else
{
psd.DirectLeaderName = ($"{psd.EmployeeId} not found in Arbor table.");
}
}
foreach (Assignment emp in psd.Assignments)
{
if (psd.EmployeeId != "VACANT")
{
IdAM_arborLU supervisor2;
if (EmployeeDirectLeaderList.TryGetValue(psd.EmployeeId, out supervisor2))
{
emp.DirectLeaderName = supervisor2.sup_name;
emp.DirectLeaderID = supervisor2.sup_pvID;
emp.DirectLeaderNetID = supervisor2.sup_netID;
}
else
{
emp.DirectLeaderName = ($"{psd.EmployeeId} not found in Arbor table.");
emp.DirectLeaderID = "--";
emp.DirectLeaderNetID = "--";
}
}
}
}
return;
}
private void UpdatePositionSlotId(PositionControlContext db)
{
string[] posnumber = (from x in Positions
select x.PositionNumber).ToArray();
var slots = (from ps1 in db.PositionSlots
where posnumber.Contains(ps1.PositionNumber)
select ps1).ToDictionary(ps => ps.PositionNumber.Trim(), ps => ps.PositionSlotId, StringComparer.OrdinalIgnoreCase);
foreach (PositionSlotDetail psd in Positions)
{
int posSlotId = 0;
if (slots.TryGetValue(psd.PositionNumber, out posSlotId))
{
psd.PositionSlotId = posSlotId;
}
}
return;
}
private void UpdateIsBudgeted(PositionControlContext db)
{
string[] posnumber = (from x in Positions
select x.PositionNumber).ToArray();
var slots = (from ps1 in db.PositionSlots
where posnumber.Contains(ps1.PositionNumber)
select ps1).ToDictionary(ps => ps.PositionNumber.Trim(), ps => ps.IsBudgeted, StringComparer.OrdinalIgnoreCase);
foreach (PositionSlotDetail psd in Positions)
{
bool isbudgeted = false;
if (slots.TryGetValue(psd.PositionNumber, out isbudgeted))
{
psd.IsBudgeted = isbudgeted;
}
}
return;
}
}

you can achieve this by writing a method:
IDMSElement.ToPositionSlot(db)
and then use it as follow:
PositionSlots myslots = elements.Select(x => x.ToPositionSlot(db))

Try to call Clients.Caller but it's not working

Hello I am trying to catch messages from database and transfer to caller but when I used Clients.Caller method then it pass me error like
Using a Hub instance not created by the HubPipeline is unsupported
If I am using
var context = GlobalHost.ConnectionManager.GetHubContext<ChatHub>();
context.Clients.All.receiver(respose);
then it replying nothing. So please help me to solve out this question.
and I am using below code:
public async Task GetAllMessages(int roomid, int fromuserId, int touserId, int index, int pageSize, int broadcastid = 0)
{
ResponseModel respose = new ResponseModel();
try
{
var model = new MessageDetailModel
{
Index = index,
PageSize = pageSize,
FromUserId = fromuserId,
ToUserId = touserId,
ChatRoomId = roomid,
BroadCastId = broadcastid
};
MesaageModel totalmessages = new MesaageModel();
List<RecentMessage> messages = new List<RecentMessage>();
var usermessages = await _userService.GetAllMessages(model);
messages.AddRange(usermessages);
foreach (var message in messages)
{
model.BroadCastMessageId = model.BroadCastId == 0 ? 0 : message.BroadCastMessageId;
model.ChatRoomMessageId = model.BroadCastId == 0 ? message.ChatRoomMessageId : 0;
List<UserDetail> userofseenby = new List<UserDetail>();
var users = await _userService.GetMessageSeenBy(model);
userofseenby.AddRange(users);
message.SeenBy = userofseenby;
}
//totalmessages.Messages.AddRange(messages);
totalmessages.Messages = messages;
totalmessages.UnseenMessageCount = await _userService.GetUnSeenCount(messages.FirstOrDefault().ChatRoomId, fromuserId);
if (messages.FirstOrDefault().IsBroadCast == true)
totalmessages.Users = (List<UserDetail>)await _userService.GetUsersByBroadCastId(messages.FirstOrDefault().BroadCastId);
else if (messages.FirstOrDefault().IsGroup == true)
totalmessages.Users = (List<UserDetail>)await _userService.GetUsersByChatRoomId((int)messages.FirstOrDefault().ChatRoomId);
respose = ResponseHelper.SuccessResponse("onAllMessagesReceived", totalmessages);
Clients.Caller.receiver(respose); // Error catch here
}
catch (Exception ex)
{
respose.ActionCommand = "onAllMessagesReceived";
respose = ResponseHelper.ErrorResponse(respose.ActionCommand, ex.ToString());
Clients.Caller.receiver(respose);
}
}
And Constructors of class is below :
public ChatHub()
{
_userService = new UserBusinessLogic();
_chatterService = new ChatterBusinessLogic();
}
public ChatHub(IChatterBusinessLogic chatterService, IUserBusinessLogic userService)
{
_chatterService = chatterService;
_userService = userService;
}
And Controller constructor are like this :
public ChatterController()
{
_userService = new UserBusinessLogic();
_chatterService = new ChatterBusinessLogic();
}
public ChatterController(IChatterBusinessLogic chatterService, IUserBusinessLogic userService)
{
_chatterService = chatterService;
_userService = userService;
}

Use workflow to evaluate dynamic expression

I would like to pass an object and expression into a dynamically created workflow to mimic the Eval function found in many languages. Can anyone help me out with what I am doing wrong? The code below is a very simple example if taking in a Policy object, multiple its premium by 1.05, then return the result. It throws the exception:
Additional information: The following errors were encountered while processing the workflow tree:
'DynamicActivity': The private implementation of activity '1: DynamicActivity' has the following validation error: Value for a required activity argument 'To' was not supplied.
And the code:
using System.Activities;
using System.Activities.Statements;
namespace ConsoleApplication1
{
class Program
{
static void Main(string[] args)
{
Policy p = new Policy() { Premium = 100, Year = 2016 };
var inputPolicy = new InArgument<Policy>();
var theOutput = new OutArgument<object>();
Activity dynamicWorkflow = new DynamicActivity()
{
Properties =
{
new DynamicActivityProperty
{
Name="Policy",
Type=typeof(InArgument<Policy>),
Value=inputPolicy
}
},
Implementation = () => new Sequence()
{
Activities =
{
new Assign()
{
To = theOutput,
Value=new InArgument<string>() { Expression = "Policy.Premium * 1.05" }
}
}
}
};
WorkflowInvoker.Invoke(dynamicWorkflow);
}
}
public class Policy
{
public int Premium { get; set; }
public int Year { get; set; }
}
}

You can use Workflow Foundation to evaluate expressions, but it is far easier to use almost any other option.
The key issue at play with your code was that you were not trying to evaluate the expression (with either VisualBasicValue or CSharpValue). Assigning InArgument`1.Expression is an attempt to set the value - not to set the value to the result of an expression.
Keep in mind that compiling expressions is fairly slow (>10ms), but the resultant compiled expression can be cached for quick executions.
Using Workflow:
class Program
{
static void Main(string[] args)
{
// this is slow, only do this once per expression
var evaluator = new PolicyExpressionEvaluator("Policy.Premium * 1.05");
// this is fairly fast
var policy1 = new Policy() { Premium = 100, Year = 2016 };
var result1 = evaluator.Evaluate(policy1);
var policy2 = new Policy() { Premium = 150, Year = 2016 };
var result2 = evaluator.Evaluate(policy2);
Console.WriteLine($"Policy 1: {result1}, Policy 2: {result2}");
}
}
public class Policy
{
public double Premium, Year;
}
class PolicyExpressionEvaluator
{
const string
ParamName = "Policy",
ResultName = "result";
public PolicyExpressionEvaluator(string expression)
{
var paramVariable = new Variable<Policy>(ParamName);
var resultVariable = new Variable<double>(ResultName);
var daRoot = new DynamicActivity()
{
Name = "DemoExpressionActivity",
Properties =
{
new DynamicActivityProperty() { Name = ParamName, Type = typeof(InArgument<Policy>) },
new DynamicActivityProperty() { Name = ResultName, Type = typeof(OutArgument<double>) }
},
Implementation = () => new Assign<double>()
{
To = new ArgumentReference<double>() { ArgumentName = ResultName },
Value = new InArgument<double>(new CSharpValue<double>(expression))
}
};
CSharpExpressionTools.CompileExpressions(daRoot, typeof(Policy).Assembly);
this.Activity = daRoot;
}
public DynamicActivity Activity { get; }
public double Evaluate(Policy p)
{
var results = WorkflowInvoker.Invoke(this.Activity,
new Dictionary<string, object>() { { ParamName, p } });
return (double)results[ResultName];
}
}
internal static class CSharpExpressionTools
{
public static void CompileExpressions(DynamicActivity dynamicActivity, params Assembly[] references)
{
// See https://learn.microsoft.com/en-us/dotnet/framework/windows-workflow-foundation/csharp-expressions
string activityName = dynamicActivity.Name;
string activityType = activityName.Split('.').Last() + "_CompiledExpressionRoot";
string activityNamespace = string.Join(".", activityName.Split('.').Reverse().Skip(1).Reverse());
TextExpressionCompilerSettings settings = new TextExpressionCompilerSettings
{
Activity = dynamicActivity,
Language = "C#",
ActivityName = activityType,
ActivityNamespace = activityNamespace,
RootNamespace = null,
GenerateAsPartialClass = false,
AlwaysGenerateSource = true,
ForImplementation = true
};
// add assembly references
TextExpression.SetReferencesForImplementation(dynamicActivity, references.Select(a => (AssemblyReference)a).ToList());
// Compile the C# expression.
var results = new TextExpressionCompiler(settings).Compile();
if (results.HasErrors)
{
throw new Exception("Compilation failed.");
}
// attach compilation result to live activity
var compiledExpression = (ICompiledExpressionRoot)Activator.CreateInstance(results.ResultType, new object[] { dynamicActivity });
CompiledExpressionInvoker.SetCompiledExpressionRootForImplementation(dynamicActivity, compiledExpression);
}
}
Compare to the equivalent Roslyn code - most of which is fluff that is not really needed:
public class PolicyEvaluatorGlobals
{
public Policy Policy { get; }
public PolicyEvaluatorGlobals(Policy p)
{
this.Policy = p;
}
}
internal class PolicyExpressionEvaluator
{
private readonly ScriptRunner<double> EvaluateInternal;
public PolicyExpressionEvaluator(string expression)
{
var usings = new[]
{
"System",
"System.Collections.Generic",
"System.Linq",
"System.Threading.Tasks"
};
var references = AppDomain.CurrentDomain.GetAssemblies()
.Where(a => !a.IsDynamic && !string.IsNullOrWhiteSpace(a.Location))
.ToArray();
var options = ScriptOptions.Default
.AddImports(usings)
.AddReferences(references);
this.EvaluateInternal = CSharpScript.Create<double>(expression, options, globalsType: typeof(PolicyEvaluatorGlobals))
.CreateDelegate();
}
internal double Evaluate(Policy policy)
{
return EvaluateInternal(new PolicyEvaluatorGlobals(policy)).Result;
}
}
Roslyn is fully documented, and has the helpful Scripting API Samples page with examples.

How to make a request asynchronously in c# (xamarin)?

I used to work with browser-based applications. for example Angular simple repository.
function getSomeData(params) {
...
return $http({
url: conf.urlDev + 'some/rest-url',
method: "GET",
params: params,
cache: true
}).then(getDataComplete);
function getDataComplete(response) {
return response.data;
}
}
How it will look the same in c# (XAMARIN for example)?
i try :
public class BaseClient
{
protected Http _client = null;
protected string _urlObj;
protected string _basePath;
public BaseClient ()
{
_client = new Http(new HttpClientHandler());
}
public string Path
{
set
{
_urlObj = value;
}
}
public async Task<Result<IList<T>>>getList<T>(Dictionary<string,object> parametrs = null)
{
if (parametrs != null)
{
foreach(KeyValuePair<string, object> keyValue in parametrs)
{
_urlObj = _urlObj.SetQueryParam(keyValue.Key, keyValue.Value);
}
}
var response = await _client.GetAsync(_urlObj.ToString());
if (response.IsSuccessStatusCode)
{
return new Result<IList<T>>()
{
Success = true,
Value = JsonConvert.DeserializeObject<IList<T>>(await response.Content.ReadAsStringAsync())
};
}
else
{
var error = new Result<IList<T>>()
{
Error = response.StatusCode.ToString(),
Message = response.ReasonPhrase,
Success = false
};
return error;
}
}
in my service:
public async Task<IList<News>> GetAllNewsByParams(DateTime from,
string orderBy = "-published",
DateTime to = new DateTime(),
int page = 1, int category = 0)
{
_client.Path = _config.NewsPath;
var dict = new Dictionary<string, object> {
{"from", from.ToString("s")},
{"order_by", orderBy.ToString()},
{"to", to.ToString("s")},
{"page", page.ToString()}
};
if (category != 0)
{
dict.Add("category", category.ToString());
}
var res = await _client.getList<News>(dict);
return res.Value;
}
and im ny viewmodel
foreach (var item in await _newsService.GetAllNewsByParams(
_To,
_OrderBy,
_From, _Page,
selectedTag == null ? _SeletedNewsTagId : selectedTag.Id))
{
NewsList.Add(item);
}
Is his query executed synchronously ?
How do I make it an asynchronous?

First of all I would really encourage you to use RestSharp, it really simplifies making HTTP requests and deserialise them. Add a RestSharp nuget package to your project. Here is how your code will look like using RestSharp.
public class BaseClient
{
protected IRestClient _client = null;
protected string _urlObj;
protected string _basePath;
public BaseClient()
{
_client = new RestClient();
}
public async Task<Result<IList<T>>> GetList<T>(string path, Dictionary<string, object> parametrs = null)
{
var request = new RestRequest(path, Method.GET);
if (parametrs != null)
{
foreach (var keyValue in parametrs)
{
request.AddQueryParameter(keyValue.Key, keyValue.Value);
}
}
var response = await _client.Execute<List<T>>(request);
if (response.IsSuccess)
{
return new Result<IList<T>>()
{
Success = true,
Value = response.Data
};
}
else
{
var error = new Result<IList<T>>()
{
Error = response.StatusCode.ToString(),
Message = response.StatusDescription,
Success = false
};
return error;
}
}
}
In your service
public async Task<IList<News>> GetAllNewsByParams(DateTime from,
string orderBy = "-published",
DateTime to = new DateTime(),
int page = 1, int category = 0)
{
var dict = new Dictionary<string, object> {
{"from", from.ToString("s")},
{"order_by", orderBy.ToString()},
{"to", to.ToString("s")},
{"page", page.ToString()}
};
if (category != 0)
{
dict.Add("category", category.ToString());
}
var res = await _client.GetList<News>(_config.NewsPath, dict);
return res.Value;
}
And in your viewmodel
var news = await _newsService.GetAllNewsByParams(
_To,
_OrderBy,
_From, _Page,
selectedTag == null ? _SeletedNewsTagId : selectedTag.Id);
foreach (var item in news)
{
NewsList.Add(item);
}
This will be 100% asynchronous.