Given the following:
public class SomePoco {
public int IntValue { get; }
}
and
CREATE TABLE SomePocoStorage (IntValue INT NOT NULL)
and
INSERT SomePocoStorage VALUES (1), (274)
If I call
connection.Query<SomePoco>("SELECT * FROM SomePocoStorage")
does Dapper handle populating the IntValue field on the returned SomePoco instances?
Good question! It isn't a scenario I've targeted, but I'd be more than happy to take a look at what would be involved. Since we already do a lot of nasty reflection, this could still be viable. Probably better as a github issue, but I'll have a look.
Update - it does now (at the current time, via repo only - not deployed):
[Fact] // passes
public void GetOnlyProperties()
{
var obj = connection.QuerySingle<HazGetOnly>(
"select 42 as [Id], 'def' as [Name];");
obj.Id.IsEqualTo(42);
obj.Name.IsEqualTo("def");
}
class HazGetOnly
{
public int Id { get; }
public string Name { get; } = "abc";
}
No because there's no way for Dapper to set the value of the property if that property only has a getter.
Related
I'm using dapper 1.50.2 with MySQL and running into a problem trying to map a left outer join child object to its parent. If I split on a column alias that doesn't actually exist in the child object, Dapper always creates a child object with default properties, even when there is nothing in the left join.
I created a simple example to demonstrate this:
public class ParentRecord
{
public string MemberID { get; set; }
public ChildRecord Child { get; set; }
}
public class ChildRecord
{
//public string Split { get; set; }
public string SomeField { get; set; }
}
using (MySqlConnection connection = new MySqlConnection(connectionString))
{
ParentRecord result = connection.Query<ParentRecord, ChildRecord, ParentRecord>(
#"SELECT 'FakeID' AS MemberID, NULL AS Split, NULL AS SomeField",
(mt, crt) =>
{
mt.Child = crt;
return mt;
},
splitOn: "Split").Single();
}
I would expect this to result a ParentRecord with the Child property set to null, but the Child property is set to a ChildRecord with all default fields.
If I uncomment the Split property in ChildRecord, or if I split on SomeField, this works as I'd expect.
Are there any good workarounds for this?
In the actual query I'm dealing with, there are multiple primary key and foreign key fields with the same names and I'd rather not change the property names in the POCOs to be unique. I'd prefer to be able to use column aliases that are just there to split on. I know this isn't normally how Dapper is set to up to work.
Any help would be appreciated, thanks.
This happen because the object Child initialize for default when you attribute the ctr param. Then the solution that I did implement was:
ParentRecord result = connection.Query<ParentRecord, ChildRecord, ParentRecord>(
#"SELECT 'FakeID' AS MemberID, NULL AS Split, NULL AS SomeField",
(mt, crt) =>
{
if (crt.SomeField != null){ mt.Child = crt; }
return mt;
},
splitOn: "Split").Single();
I have a simple query and Poco that I'm using with Dapper like so:
var jc = this.dbConnection.ExecuteScalar<JcUser>("SELECT loginid as Username,Password,coalesce(CustomerId,0) as CustomerId,TextProfileId,UxProfileId from \"user\" where id = #id", new {id = id});
Poco:
public class JcUser
{
public string UserName { get; set; }
public string Password { get; set; }
public int CustomerId{ get; set; }
public int TextProfileId { get; set; }
public int UxProfileId { get; set; }
}
When this executes it throws an exception with the message
Value is not a convertible object: System.String to JcUser
The stack trace ends up at: at System.Convert.ToType (System.Object value, System.Type conversionType, IFormatProvider provider, Boolean try_target_to_type)
Any ideas why its doing this?
Thanks
UPDATE: Using var jc = this.dbConnection.Query<JcUser>("SELECT loginid as Username,Password,coalesce(CustomerId,0) as CustomerId,TextProfileId,UxProfileId from \"user\" where id = #id", new {id = id}).First(); appears to work. I also realise I'm a moron and ExecuteScalar is only for one value. However, is my update the best way to retrieve only one row?
ExecuteScalar maps to the ADO.NET method of the same name. It returns at most one cell: one grid, one row, one column. As such, it is not intended for use with complex objects, and cannot work correctly in your case as you have multiple columns.
Dapper assumes you would only use that with simple types like int, string etc.
In your case, use:
var jc = this.dbConnection.Query<JcUser>(
sql, args).SingleOrDefault();
If you want to avoid a hidden List<> allocation you could also pass buffered: false.
I'm looking for a way to map a row of the following table with the following object :
create table Foo (
Id BIGINT IDENTITY (1, 1) NOT NULL,
A int,
ACertainty float,
B string,
BCertainty float
....
)
public class FuzzyValue<T>{
public T Value { get; private set; }
public double Certainty { get; private set; }
}
class Foo {
public FuzzyValue<int> A { get; set;}
public FuzzyValue<string> B { get; set;}
...
}
Obviously, I can have dapper return a dynamic and do the mapping manually, but this manual tedious work kind of defeats the purpose of dapper, doesn't it?
Is there an easy way to have dapper do the mapping automatically?
I ended up writing a not so trivial mapper to do this.
If someone needs it, the source is here and there's a nuget package available here
I have the following class and test. I want to test passing a null value as a parameter to the constructor and are expecting an ArgumentNullException. But since I use the Autofixture's CreateAnonymous method I get a TargetInvocationException instead.
What is the correct way to write those kinds of tests?
public sealed class CreateObject : Command {
// Properties
public ObjectId[] Ids { get; private set; }
public ObjectTypeId ObjectType { get; private set; }
public UserId CreatedBy { get; private set; }
// Constructor
public CreateObject(ObjectId[] ids, ObjectTypeId objectType, UserId createdBy) {
Guard.NotNull(ids, "ids");
Guard.NotNull(objectType, "objectType");
Guard.NotNull(createdBy, "createdBy");
Ids = ids;
ObjectType = objectType;
CreatedBy = createdBy;
}
}
[TestMethod]
[ExpectedException(typeof(ArgumentNullException))]
public void constructor_with_null_ids_throw() {
fixture.Register<ObjectId[]>(() => null);
fixture.CreateAnonymous<CreateObject>();
}
IMO, Ruben Bartelink's comment is the best answer.
With AutoFixture.Idioms, you can do this instead:
var fixture = new Fixture();
var assertion = new GuardClauseAssertion(fixture);
assertion.Verify(typeof(CreateObject).GetConstructors());
The Verify method will provide you with a quite detailed exception message if any constructor argument in any constructor is lacking a Guard Clause.
FWIW, AutoFixture extensively uses Reflection, so I don't consider it a bug that it throws a TargetInvocationException. While it could unwrap all TargetInvocationException instances and rethrow their InnerException properties, that would also mean disposing of (potentially) valuable information (such as the AutoFixture stack trace). I've considered this, but don't want to take AutoFixture in that direction, for exactly that reason. A client can always filter out information, but if information is removed prematurely, no client can get it back.
If you prefer the other approach, it's not too hard to write a helper method that unwraps the exception - perhaps something like this:
public Exception Unwrap(this Exception e)
{
var tie = e as TargetInvocationException;
if (tie != null)
return tie.InnerException;
return e;
}
I came across this while I was searching for something similar. I would like to add that, combined with automoqcustomization and xunit, below code also works and its much cleaner.
[Theory, AutoMoqData]
public void Constructor_GuardClausesArePresent(GuardClauseAssertion assertion)
{
assertion.Verify(typeof(foo).GetConstructors());
}
You just need to create the AutoMoqData attribute as follows.
public class AutoMoqDataAttribute : AutoDataAttribute
{
public AutoMoqDataAttribute() : base(() => new Fixture().Customize(new AutoMoqCustomization()))
{
}
}
I added a RIA Domain Service method to return a simple NameValuePair of two properties from a table (and filtered on a key value).
It compiles fine, but blows up every time without giving a useful error.
What am I missing? (probably something really obvious)
e.g.:
public IQueryable<NameValuePair> GetNameValues(int keyId)
{
// NOTE: I can breakpoint here and the correct keyId is passed
// it blows up on returning from this method
return from p in this.ObjectContext.NameTable
where p.KeyId == keyId
select new NameValuePair(p.NameValue, p.NameType);
}
Simple NameValuePair Code:
public class NameValuePair
{
[Key]
public string Name { get; set; }
public string Value { get; set; }
public NameValuePair()
{
}
public NameValuePair( string name, string value)
{
this.Name = name;
this.Value = value;
}
}
Update:
I tried returning a query on a static list of NameValuePair objects and that works fine (but is not useful).
I tried this here and got the error: base {System.SystemException} = {"Only parameterless constructors and initializers are supported in LINQ to Entities."}
So you have to change it to create the object first, then pass the property values:
public IQueryable<NameValuePair> GetNameValues(int keyId)
{
return from p in this.ObjectContext.NameTable
where p.KeyId == keyId
select new NameValuePair {Name = p.NameValue, Value = p.NameType};
}