I am attempting to use Newtonsoft.Json.Net35 Version 4.0.2.0 to deserialize an ADO.NET DataTable that contains null values. Serialization works fine:
[Test]
public void SerializeDataTableWithNull()
{
var table = new DataTable();
table.Columns.Add("item");
table.Columns.Add("price", typeof(double));
table.Rows.Add("shirt", 49.99);
table.Rows.Add("pants", 54.99);
table.Rows.Add("shoes"); // no price
var json = JsonConvert.SerializeObject(table);
Assert.AreEqual(#"["
+ #"{""item"":""shirt"",""price"":49.99},"
+ #"{""item"":""pants"",""price"":54.99},"
+ #"{""item"":""shoes"",""price"":null}]", json);
}
Deserialization works fine if values are missing:
[Test]
public void DerializeDataTableWithImplicitNull()
{
const string json = #"["
+ #"{""item"":""shirt"",""price"":49.99},"
+ #"{""item"":""pants"",""price"":54.99},"
+ #"{""item"":""shoes""}]";
var table = JsonConvert.DeserializeObject<DataTable>(json);
Assert.AreEqual("shirt", table.Rows[0]["item"]);
Assert.AreEqual("pants", table.Rows[1]["item"]);
Assert.AreEqual("shoes", table.Rows[2]["item"]);
Assert.AreEqual(49.99, (double)table.Rows[0]["price"], 0.01);
Assert.AreEqual(54.99, (double)table.Rows[1]["price"], 0.01);
Assert.IsInstanceOf(typeof(System.DBNull), table.Rows[2]["price"]);
}
If, however, values are explicitly null:
[Test]
public void DerializeDataTableWithExplicitNull()
{
const string json = #"["
+ #"{""item"":""shirt"",""price"":49.99},"
+ #"{""item"":""pants"",""price"":54.99},"
+ #"{""item"":""shoes"",""price"":null}]";
var table = JsonConvert.DeserializeObject<DataTable>(json);
Assert.AreEqual("shirt", table.Rows[0]["item"]);
Assert.AreEqual("pants", table.Rows[1]["item"]);
Assert.AreEqual("shoes", table.Rows[2]["item"]);
Assert.AreEqual(49.99, (double)table.Rows[0]["price"], 0.01);
Assert.AreEqual(54.99, (double)table.Rows[1]["price"], 0.01);
Assert.IsInstanceOf(typeof(System.DBNull), table.Rows[2]["price"]);
}
DeserializeObject throws "System.ArgumentException : Cannot set Column 'price' to be null. Please use DBNull instead." The following workaround works for my particular JSON:
var regex = new Regex(#",?""[_\w]+"":null");
var nullless = regex.Replace(json, string.Empty);
var table = JsonConvert.DeserializeObject<DataTable>(nullless);
but like all regular expression-based kludges this is clearly brittle.
Finally, the questions:
Is this a bug?
Json.NET has many events that can be hooked. Is there a way to get notified when a when a null value is encountered and explicitly set the value to System.DBNull?
Thanks in advance,
Frank
It looks like this is a bug which is easily fixed by replacing
dr[columnName] = reader.Value
with
dr[columnName] = reader.Value ?? System.DBNull.Value
in Newtonsoft.Json.Converters.DataTableConverter. I have entered an issue in the tracker.
Related
I have an object with several really large string properties. In addition, it has a simple timestamp property.
What I trying to achieve is to update only timestamp property without getting the whole huge object to the server.
Eventually, I would like to use EF and to do in the most performant way something equivalent to this:
update [...]
set [...] = [...]
where [...]
Using the following, you can update a single column:
var yourEntity = new YourEntity() { Id = id, DateProp = dateTime };
using (var db = new MyEfContextName())
{
db.YourEntities.Attach(yourEntity);
db.Entry(yourEntity).Property(x => x.DateProp).IsModified = true;
db.SaveChanges();
}
OK, I managed to handle this. The solution is the same as proposed by Seany84, with the only addition of disabling validation, in order to overcome issue with required fields. Basically, I had to add the following line just before 'SaveChanges():
db.Configuration.ValidateOnSaveEnabled = false;
So, the complete solution is:
var yourEntity = new YourEntity() { Id = id, DateProp = dateTime };
using (var db = new MyEfContextName())
{
db.YourEntities.Attach(yourEntity);
db.Entry(yourEntity).Property(x => x.DateProp).IsModified = true;
db.Configuration.ValidateOnSaveEnabled = false;
db.SaveChanges();
}
I have some word templates(maybe thousands). Each template has merge fields which will be filled from database. I don`t like writing separate code for every template and then build the application and deploy it whenever a template is changed or a field on the template is added!
Instead, I'm trying to define all merge fields in a separate xml file and for each field I want to write the "query" which will be called when needed. EX:
mergefield1 will call query "Case.Parties.FirstOrDefault.NameEn"
mergefield2 will call query "Case.CaseNumber"
mergefield3 will call query "Case.Documents.FirstOrDefault.DocumentContent.DocumentType"
Etc,
So, for a particular template I scan its merge fields, and for each merge field I take it`s "query definition" and make that request to database using EntityFramework and LINQ. Ex. it works for these queries: "TimeSlots.FirstOrDefault.StartDateTime" or
"Case.CaseNumber"
This will be an engine which will generate word documents and fill it with merge fields from xml. In addition, it will work for any new template or new merge field.
Now, I have worked a version using reflection.
public string GetColumnValueByObjectByName(Expression<Func<TEntity, bool>> filter = null, string objectName = "", string dllName = "", string objectID = "", string propertyName = "")
{
string objectDllName = objectName + ", " + dllName;
Type type = Type.GetType(objectDllName);
Guid oID = new Guid(objectID);
dynamic Entity = context.Set(type).Find(oID); // get Object by Type and ObjectID
string value = ""; //the value which will be filled with data from database
IEnumerable<string> linqMethods = typeof(System.Linq.Enumerable).GetMethods(BindingFlags.Static | BindingFlags.Public).Select(s => s.Name).ToList(); //get all linq methods and save them as list of strings
if (propertyName.Contains('.'))
{
string[] properies = propertyName.Split('.');
dynamic object1 = Entity;
IEnumerable<dynamic> Child = new List<dynamic>();
for (int i = 0; i < properies.Length; i++)
{
if (i < properies.Length - 1 && linqMethods.Contains(properies[i + 1]))
{
Child = type.GetProperty(properies[i]).GetValue(object1, null);
}
else if (linqMethods.Contains(properies[i]))
{
object1 = Child.Cast<object>().FirstOrDefault(); //for now works only with FirstOrDefault - Later it will be changed to work with ToList or other linq methods
type = object1.GetType();
}
else
{
if (linqMethods.Contains(properies[i]))
{
object1 = type.GetProperty(properies[i + 1]).GetValue(object1, null);
}
else
{
object1 = type.GetProperty(properies[i]).GetValue(object1, null);
}
type = object1.GetType();
}
}
value = object1.ToString(); //.StartDateTime.ToString();
}
return value;
}
I`m not sure if this is the best approach. Does anyone have a better suggestion, or maybe someone has already done something like this?
To shorten it: The idea is to make generic linq queries to database from a string like: "Case.Parties.FirstOrDefault.NameEn".
Your approach is very good. I have no doubt that it already works.
Another approach is using Expression Tree like #Egorikas have suggested.
Disclaimer: I'm the owner of the project Eval-Expression.NET
In short, this library allows you to evaluate almost any C# code at runtime (What you exactly want to do).
I would suggest you use my library instead. To keep the code:
More readable
Easier to support
Add some flexibility
Example
public string GetColumnValueByObjectByName(Expression<Func<TEntity, bool>> filter = null, string objectName = "", string dllName = "", string objectID = "", string propertyName = "")
{
string objectDllName = objectName + ", " + dllName;
Type type = Type.GetType(objectDllName);
Guid oID = new Guid(objectID);
object Entity = context.Set(type).Find(oID); // get Object by Type and ObjectID
var value = Eval.Execute("x." + propertyName, new { x = entity });
return value.ToString();
}
The library also allow you to use dynamic string with IQueryable
Wiki: LINQ-Dynamic
SO follow this example
example and how make a fake DBContex For test my test using just this work fine
[Test]
public void CiudadIndex()
{
var ciudades = new FakeDbSet<Ciudad>
{
new Ciudad {CiudadId = 1, EmpresaId =1, Descripcion ="Santa Cruz", FechaProceso = DateTime.Now, MarcaBaja = null, UsuarioId = 1},
new Ciudad {CiudadId = 2, EmpresaId =1, Descripcion ="La Paz", FechaProceso = DateTime.Now, MarcaBaja = null, UsuarioId = 1},
new Ciudad {CiudadId = 3, EmpresaId =1, Descripcion ="Cochabamba", FechaProceso = DateTime.Now, MarcaBaja = null, UsuarioId = 1}
};
//// Create mock unit of work
var mockData = new Mock<IContext>();
mockData.Setup(m => m.Ciudades).Returns(ciudades);
// Setup controller
var homeController = new CiudadController(mockData.Object);
// Invoke
var viewResult = homeController.Index();
var ciudades_de_la_vista = (IEnumerable<Ciudad>)viewResult.Model;
// Assert..
}
Iam tryign now to use Autofixture-Moq
to create "ciudades" but I cant. I try this
var fixture = new Fixture();
var ciudades = fixture.Build<FakeDbSet<Ciudad>>().CreateMany<FakeDbSet<Ciudad>>();
var mockData = new Mock<IContext>();
mockData.Setup(m => m.Ciudades).Returns(ciudades);
I get this error
Cant convert System.Collections.Generic.IEnumerable(FakeDbSet(Ciudad)) to System.Data.Entity.IDbSet(Ciudad)
cant put "<>" so I replace with "()" in the error message
Implementation of IContext and FakeDbSet
public interface IContext
{
IDbSet<Ciudad> Ciudades { get; }
}
public class FakeDbSet<T> : IDbSet<T> where T : class
how can make this to work?
A minor point... In stuff like:
var ciudades_fixture = fixture.Build<Ciudad>().CreateMany<Ciudad>();
The second type arg is unnecessary and should be:
var ciudades_fixture = fixture.Build<Ciudad>().CreateMany();
I really understand why you need a FakeDbSet and the article is a bit TL;DR... In general, I try to avoid faking and mucking with ORM bits and instead dealing with interfaces returning POCOs to the max degree possible.
That aside... The reason the normal syntax for initialising the list works is that there is an Add (and IEnumerable) in DBFixture. AutoFixture doesn't have a story for that pattern directly (after all it is compiler syntactic sugar and not particularly amenable to reflection or in line with any other conventions) but you can use AddManyTo as long as there is an ICollection in play. Luckily, within the impl of FakeDbSet as in the article, the following gives us an in:-
public ObservableCollection<T> Local
{
get { return _data; }
}
As ObservableCollection<T> derives from ICollection<T>, you should be able to:
var ciudades = new FakeDbSet<Cuidad>();
fixture.AddManyTo(ciudades.Local);
var mockData = new Mock<IContext>();
mockData.Setup(m => m.Ciudades).Returns(ciudades);
It's possible to wire up a customization to make this prettier, but at least you have a way to manage it. The other option is to have something implement ICollection (or add a prop with a setter taking IEnumerable<T> and have AF generate the parent object, causing said collection to be filled in.
Long superseded side note: In your initial question, you effectively have:
fixture.Build<FakeDbSet<Ciudad>>().CreateMany()
The problem becomes clearer then - you are asking AF to generate Many FakeDbSet<Ciudad>s, which is not what you want.
I haven't used AutoFixture in a while, but shouldn't it be:
var ciudades = new FakeDbSet<Ciudad>();
fixture.AddManyTo(ciudades);
for the moment I end doing this, I will keep reading about how use automoq, cause I'm new in this
var fixture = new Fixture();
var ciudades_fixture = fixture.Build<Ciudad>().CreateMany<Ciudad>();
var ciudades = new FakeDbSet<Ciudad>();
foreach (var item in ciudades_fixture)
{
ciudades.Add(item);
}
var mockData = new Mock<IContext>();
fixture.Create<Mock<IContext>>();
mockData.Setup(r => r.Ciudades).Returns(ciudades);
I'm trying to call a stored procedure from EntityFramework which uses Table-value parameter.
But when I try to do function import I keep getting a warning message saying -
The function 'InsertPerson' has a parameter 'InsertPerson_TVP' at
parameter index 0 that has a data type 'table type' which is currently
not supported for the target .NET Framework version. The function was
excluded.
I did a initial search here and found few posts which says It's possible in EntityFrameWork with some work arounds and few saying it's not supported in current versions.
Does any one know a better approach or solution for this problem?
I ended up doing this, Please note we are working on EF DataContext(not ObjectContext)
Executing a Stored procedure with output parameter
using (DataContext context = new DataContext())
{
////Create table value parameter
DataTable dt = new DataTable();
dt.Columns.Add("Displayname");
dt.Columns.Add("FirstName");
dt.Columns.Add("LastName");
dt.Columns.Add("TimeStamp");
DataRow dr = dt.NewRow();
dr["Displayname"] = "DisplayName";
dr["FirstName"] = "FirstName";
dr["LastName"] ="LastName";
dr["TimeStamp"] = "TimeStamp";
dt.Rows.Add(dr);
////Use DbType.Structured for TVP
var userdetails = new SqlParameter("UserDetails", SqlDbType.Structured);
userdetails.Value = dt;
userdetails.TypeName = "UserType";
////Parameter for SP output
var result = new SqlParameter("ResultList", SqlDbType.NVarChar, 4000);
result.Direction = ParameterDirection.Output;
context.Database.ExecuteSqlCommand("EXEC UserImport #UserDetails, #ResultList OUTPUT", userdetails, result);
return result == null ? string.Empty : result.Value.ToString();
}
My Table-Value-Parameter (UDT Table) script looks like this:
CREATE TYPE [dbo].[UserType] AS TABLE (
[DisplayName] NVARCHAR (256) NULL,
[FirstName] NVARCHAR (256) NULL,
[LastName] NVARCHAR (256) NULL,
[TimeStamp] DATETIME NULL
)
And my store procedure begins like
CREATE PROCEDURE UserImport
-- Add the parameters for the stored procedure here
#UserDetails UserType Readonly,
#ResultList NVARCHAR(MAX) output
AS
For Stored procedure without output parameter we don't need any ouput parameter added/passed to SP.
Hope it helps some one.
Perhaps we could also consider the SqlQuery method:
[Invoke]
public SomeResultType GetResult(List<int> someIdList)
{
var idTbl = new DataTable();
idTbl.Columns.Add("Some_ID");
someIdList.ForEach(id => idTbl.Rows.Add(id));
var idParam = new SqlParamter("SomeParamName", SqlDbType.Structured);
idParam.TypeName = "SomeTBVType";
idParam.Value = idTbl;
// Return type will be IEnumerable<T>
var result = DbContext.Database.SqlQuery<SomeResultType>("EXEC SomeSPName, #SomeParamName", idParam);
// We can enumerate the result...
var enu = result.GetEnumerator();
if (!enu.MoveNext()) return null;
return enu.Current;
}
var detailTbl = new DataTable();
detailTbl.Columns.Add("DetailID");
detailTbl.Columns.Add("Qty");
txnDetails.ForEach(detail => detailTbl.Rows.Add(detail.DetailID, detail.Qty));
var userIdParam = new System.Data.SqlClient.SqlParameter("#UserID", SqlDbType.Int);
userIdParam.Value = 1;
var detailParam = new System.Data.SqlClient.SqlParameter("#Details", SqlDbType.Structured);
detailParam.TypeName = "DetailUpdate";
detailParam.Value = detailTbl;
var txnTypeParam = new System.Data.SqlClient.SqlParameter("#TransactionType", SqlDbType.VarChar);
txnTypeParam.Value = txnType;
var result = await db.Database.ExecuteSqlCommandAsync("MySP #UserID, #Details, #TransactionType", userIdParam, detailParam, txnTypeParam);
if(result >= 0)
return StatusCode(HttpStatusCode.OK);
else
return StatusCode(HttpStatusCode.InternalServerError);
I am having a problem with the Dynamic Linq Library. I get a the following error "ParserException was unhandled by user code ')" or ','". I have a Dicitionary and I want to create a query based on this dictionary. So I loop through my dictionary and append to a string builder "PersonId = (GUID FROM DICTIONARY). I think the problem is were I append to PersonId for some reason I can't seem to convert my string guid to a Guid so the dynamic library don't crash.
I have tried this to convert my string guid to a guid, but no luck.
query.Append("(PersonId = Guid(" + person.Key + ")");
query.Append("(PersonId = " + person.Key + ")");
I am using VS 2010 RTM and RIA Services as well as the Entity Framework 4.
//This is the loop I use
foreach (KeyValuePair<Guid, PersonDetails> person in personsDetails)
{
if ((person.Value as PersonDetails).IsExchangeChecked)
{
query.Append("(PersonId = Guid.Parse(" + person.Key + ")");
}
}
//Domain service call
var query = this.ObjectContext.Persons.Where(DynamicExpression.ParseLambda<Person, bool>(persons));
Please help, and if you know of a better way of doing this I am open to suggestions.
For GUID comparison with dynamic linq use query properties and the Equals() method like in the provided sample.
var items = new[]
{
new { Id = Guid.Empty },
new { Id = Guid.NewGuid() },
new { Id = Guid.NewGuid() },
new { Id = Guid.NewGuid() }
};
var result = items.AsQueryable()
.Where("Id.Equals(#0)", Guid.Empty)
.Any();
Use a parameterized query, e.g.:
var query = this.ObjectContext.Persons.Where(
"PersonId = #1", new [] { person.Key } );
Did you try(notice the extra ')' ).
query.Append("(PersonId = Guid(" + person.Key + "))");