I need a little help with some mappings I am doing.
I am mapping a Model which has two fields
public ProductCategory
public string FirstType
public string SecondType
to another Model which has only one field
public string ProductType
Now I have to map the First or Second Type to ProductType based on a the content of ProductCategory.And if the condition is not met the ProductType should be null
For example I need something like this:
.ForMember(dest => dest.ProductType, opt => opt.MapFrom(src =>
{
if (src.ProductCategory.Equals("something")
{
src.FirstType
}
else if (src.ProductCategory.Equals("something")
{
src.SecondType
}
else
{
null
}
}))
Of course the syntax is completely wrong and obviously won`t work , I just wanted to explain what I am trying to achieve.
I have a temporary solution
.ForMember(dest => dest.ProductType, opt => opt.MapFrom(src => src.ProductCategory.Contains("something") ? src.FirstType: src.SecondType))
but it is not completely what I need.
Any suggestions?
Thanks in advance
What you can do to avoid making the map code look very tangled is to actually separate it into methods that you actually know require some checking for the right value to be assigned.
Here's the code
.ForMember(dest => dest.ProductType, opt => opt.MapFrom(src => CalculateProductCategory(src.ProductCategory))) and then you write your own CalculateProductCategory
And your method would look something like this
public ProductType CalculateProductCategory(ProductCategory category) {
if (productCategory.Equals("something")
{
return FirstType
}
else if (productCategory.Equals("something")
{
return SecondType
}
else
{
return null
}
}
Related
I've got a source class like the following:
public class Source
{
public Field[] Fields { get; set; }
public Result[] Results { get; set; }
}
And have a destination class like:
public class Destination
{
public Value[] Values { get; set; }
}
So I want to map from EITHER Fields or Results to Values depending on which one is not null (only one will ever have a value).
I tried the following map:
CreateMap<Fields, Values>();
CreateMap<Results, Values>();
CreateMap<Source, Destination>()
.ForMember(d => d.Values, opt =>
{
opt.PreCondition(s => s.Fields != null);
opt.MapFrom(s => s.Fields });
})
.ForMember(d => d.Values, opt =>
{
opt.PreCondition(s => s.Results != null);
opt.MapFrom(s => s.Results);
});
Only issue with this is that it looks if the last .ForMember map doesn't meet the condition it wipes out the mapping result from the first map.
I also thought about doing it as a conditional operator:
opt => opt.MapFrom(s => s.Fields != null ? s.Fields : s.Results)
But obviously they are different types so don't compile.
How can I map to a single property from source properties of different types based on a condition?
Thanks
There is a ResolveUsing() method that allows you for more complex binding and you can use a IValueResolver or a Func. Something like this:
CreateMap<Source, Destination>()
.ForMember(dest => dest.Values, mo => mo.ResolveUsing<ConditionalSourceValueResolver>());
And the value resolver depending on your needs may look like:
public class ConditionalSourceValueResolver : IValueResolver<Source, Destination, Value[]>
{
public Value[] Resolve(Source source, Destination destination, Value[] destMember, ResolutionContext context)
{
if (source.Fields == null)
return context.Mapper.Map<Value[]>(source.Results);
else
return context.Mapper.Map<Value[]>(source.Fields);
}
}
Following #animalito_maquina answer.
Here is an update for 8.0 Upgrade:
CreateMap<Source, Destination>()
.ForMember(dest => dest.Values, mo => mo.MapFrom<ConditionalSourceValueResolver>());
And to save you time, ValueResolvers are not supported for Queryable Extensions
ResolveUsing is not available, try this.
It's working for me
CreateMap<Source, Destination>()
.ForMember(opt => opt.value, map =>
map.MapFrom((s, Ariel) => s.Fields != null ? s.Fields : s.Results));
Is there a way to pass the properties I want to retrieve from the DB in a Select dynamically, I don't know the properties I need beforehand and I don't want to write the conditions in my repository.
I don't want to retrieve all the fields at once, just the ones I need based on some conditions.
For example:
public class Student
{
public string Property1 {get; set;}
public string Property2 {get; set;}
//other properties here
[NotMapped]
public string Selected
{
if(condition)
return Property1;
else
return Property2;
}
}
and in the service layer I have
query.Select(s => new StudentViewModel
{
Value = s.Selected; //this one will get the property we want based on a condition
//other stuff here
//OtherValue = s.OtherProperty
}
).FirstOrDefault();
Selector
An easy but ugly way is to use a Selector:
query.Select(Selector()).FirstOrDefault();
And the Selector can look like this:
private static Expression<Func<Student, StudentViewModel>> Selector()
{
if (Condition())
return x => new StudentViewModel
{
Name = x.Property1,
OtherName = x.OtherName
};
return x => new StudentViewModel
{
Name = x.Property2,
OtherName = x.OtherName
};
}
As you can see the obviously downside here is that you need to copy/paste all other selected properties. That is why its ugly.
AutoMapper
Configs
You can use AutoMapper with different configurations. First you need to define a standard mapping for all properties that don't need to be dynamic.
public static void AddStandardStudentMap(this IMappingExpression<Student, StudentViewModel> map)
{
map.ForMember(dest => dest.OtherName, opt => opt.MapFrom(src => src.OtherProperty))
.ForMember(dest => dest.OtherName2, opt => opt.MapFrom(src => src.OtherProperty2));
// you can concat .ForMember() for each property you need.
}
Next, you need to define the different configs and add the AddStandardStudentMap method to each invidual mapping.
var config1 = new MapperConfiguration(cfg =>
cfg.CreateMap<Student, StudentViewModel>()
.ForMember(dest => dest.Name, opt => opt.MapFrom(src => src.Property1))
.AddStandardStudentMap()
);
var config2 = new MapperConfiguration(cfg =>
cfg.CreateMap<Student, StudentViewModel>()
.ForMember(dest => dest.Name, opt => opt.MapFrom(src => src.Property2))
.AddStandardStudentMap()
);
After this, just use your conditions to decide which config do you need
IConfigurationProvider provider;
if(Condition())
provider = config1;
else
provider = config2;
And then instead of .Select() use:
query.ProjectTo<StudentViewModel>(provider).FirstOrDefault();
As we can see this solution is still ugly and has a lot of overhead but its needed in some cases, thats why i stated it here.
Expression
This is a bit similar to the Configs but brings you more flexibility and less writing effort.
First create a config but this time with a Selector
var config = new MapperConfiguration(cfg =>
cfg.CreateMap<Student, StudentViewModel>()
.ForMember(dest => dest.OtherName, opt => opt.MapFrom(src => src.OtherName))
.ForMember(dest => dest.OtherName2, opt => opt.MapFrom(src => src.OtherName2))
// and so on. Map all your properties that are not dynamically.
// and then the Selector
.ForMember(dest => dest.Name, opt => opt.MapFrom(src => Selector()))
);
The Selector method can look like this:
private static Expression<Func<Student, StudentViewModel>> Selector()
{
if(Condition())
return src => src.Property1;
else
return src => src.Property2;
}
And then just use it like the configs solution but without selecting a particular config:
query.ProjectTo<StudentViewModel>(config).FirstOrDefault();
Conclusion
I know this is a lot input and there are even more possibilities to achieve the behaviour that you want, with or without AutoMapper. But i would suggest you (grounded on the information you gave us) to use AutoMapper with Expressions. It should give the flexibility you need and is extensible for further requirements.
I am trying to use AutoMapper 3 to project a class with an Integer property to another class with a String property.
When the query is executed then I get the following exception:
System.NotSupportedException: LINQ to Entities does not recognize the method 'System.String ToString()' method, and this method cannot be translated into a store expression.
Here are the relevant parts of the code:
public partial class Lookup
{
public int LookupId { get; set; }
public int LookupTypeId { get; set; }
public string Value { get; set; }
public int SequencialOrder { get; set; }
public virtual LookupType LookupType { get; set; }
}
public class LookupProfile : Profile
{
protected override void Configure()
{
CreateMap<Lookup, SelectListItem>()
.ForMember(dest => dest.Value, opt => opt.MapFrom(src => src.LookupId.ToString()))
.ForMember(dest => dest.Text, opt => opt.MapFrom(src => src.Value));
}
}
And the query looks like:
Provinces = _db.Lookups.Project().To<SelectListItem>().ToList()
Question:
Is there a way I could configure the LookupProfile to do the proper mapping and still work inside Linq To Entities?
Or is there another way I could make the projection work with Linq to Entities?
The solution was to use the SqlFunctions.StringConvert function.
Here is the modified profile code that made everything work:
public class LookupProfile : Profile
{
protected override void Configure()
{
CreateMap<Lookup, SelectListItem>()
.ForMember(dest => dest.Value, opt => opt.MapFrom(src => SqlFunctions.StringConvert((double)src.LookupId)))
.ForMember(dest => dest.Text, opt => opt.MapFrom(src => src.Value));
}
}
I'll leave this answer here in case anyone else stumbles upon the same issue I had.
One problem with the current accepted answer is that if you're on an ASP.NET MVC project using client-side validation through helpers, you'll get a validation error for the ID field (if it's a number): The field [field] must be a number. That happens because the result from SqlFunctions.StringConvert returns a string with several leading spaces, so the unobtrusive validator doesn't see it as a number.
The way I solved this issue on my own was to create a generic SelectListItem<T> class that inherits from SelectListItem, hides the original Value property and implements its own Value setter:
public class SelectListItem<T> : SelectListItem
{
public new T Value {
set {
base.Value = value.ToString();
}
// Kind of a hack that I had to add
// otherwise the code won't compile
get {
return default(T);
}
}
}
Then on the Automapper profile I would map the items like so:
public class LookupProfile : Profile
{
protected override void Configure()
{
//Use whatever datatype is appropriate: decimal, int, short, etc
CreateMap<Lookup, SelectListItem<int>>()
.ForMember(dest => dest.Value, opt => opt.MapFrom(src => src.LookupId))
.ForMember(dest => dest.Text, opt => opt.MapFrom(src => src.Value));
}
}
And finally on the Service layer, I would map the entities to the generic class and return an IEnumerable<SelectListItem>.
public IEnumerable<SelectListItem> GetList() {
return _db.Lookups.Project().To<SelectListItem<int>>().ToList();
}
This way you'll get the right value for the Value property without trailing spaces.
Can AutoMapper be "persuaded" to temporarily suspend particular mappings?
To illustrate what am trying to accomplish, I will use an illustration. Suppose that I have a repository, StudentRepository, that uses LINQ to interacts with database objects (tables) like Students, Courses, Activities, Clubs etc. On the application side, there are matching domain objects Student, Course, Activity, Club. The Student class contains array members of type Course, Activity, and Club like:
public class Student
{
// ... more members
public Course[] Courses { get; set; }
public Activity[] Activities { get; set; }
public Club[] Clubs { get; set; }
// ... even more members
}
AutoMapper is configured to map the database objects to the domain objects where the mappings are defined in a static constructor of StudentRepository like:
public class StudentRepository : IStudentRepository
{
static class StudentRepository
{
// ... other mappings
Mapper.CreateMap<TableStudent, Student>()
.ForMember(dest => dest.Courses, opt => opt.MapFrom(src => Mapper.Map<IEnumerable<Course>>(src.TableCourses)))
.ForMember(dest => dest.Activities, opt => opt.MapFrom(src => Mapper.Map<IEnumerable<Activity>>(src.TableActivities)))
.ForMember(dest => dest.Clubs, opt => opt.MapFrom(src => Mapper.Map<IEnumerable<Clubs>>(src.TableClubs)))
// where TableStudents, TableCourses, TableActivities, TableClubs are database entities
// ... yet more mappings
}
}
Is it possible to "persuade" AutoMapper to suspend the mappings within one function block? For example:
public Student[] GetStudents()
{
DataContext dbContext = new StudentDBContext();
var query = dbContext.Students;
// => SUSPEND CONFIGURATION MAPPINGS for Subjects, Activities and Clubs WHILE STILL making use of others
// => The idea here it to take personal charge of 'manually' setting the particular members (*for some specific reasons)
var students = Mapper.Map<Student>(query); // => Still be able to use AutoMapper to map other members
}
public Student[] OtherStudentRepositoryMethods()
{
// Other repository methods continue to make use of the mappings configured in the static constructor
}
NOTE "for some specific reasons": One reason one may want to take control away from AutoMapper would be this http://codebetter.com/davidhayden/2007/08/06/linq-to-sql-query-tuning-appears-to-break-down-in-more-advanced-scenarios/ where in the case of a 1:n associations, LINQ to SQL only supports joining-in one 1:n association per query. AutoMapper would be inefficient here - making N calls to load Courses for N students returned, N more calls to load Activities for the same N students returned, and possibly N more calls to load Clubs for the same N students returned.
Is it possible to "persuade" AutoMapper to suspend the mappings within one function block?
As I know, the best way to do it - use Ignore() like this
public class StudentRepository : IStudentRepository
{
static class StudentRepository
{
// ... other mappings
Mapper.CreateMap<TableStudent, Student>()
.ForMember(dest => dest.Courses, opt => opt.Ignore())
.ForMember(dest => dest.Activities, opt => opt.Ignore())
.ForMember(dest => dest.Clubs, opt => opt.Ignore())
// where TableStudents, TableCourses, TableActivities, TableClubs are database entities
// ... yet more mappings
}
}
Also, as it was noticed before, I'd recommend you to use different profiles for each goal you want to achieve.Here is a example
public BaseService()
{
AutoMapperRegistry.Configure();
}
public class AutoMapperRegistry
{
public static void Configure()
{
Mapper.Initialize(x =>
{
x.AddProfile<ServiceProfile1>();
x.AddProfile<ServiceProfileReverseProfile1>();
});
}
}
public class ServiceProfile1 : Profile
{
protected override string ProfileName
{
get
{
return "ServiceProfile1";
}
}
protected override void Configure()
{
Mapper.CreateMap<DataContract_Sub, DTO_Sub>();
Mapper.CreateMap<DataContract, DTO>()
.ForMember(x => x.DataContract_Sub, opt => opt.MapFrom(y => y.DTO_Sub))
.BeforeMap((s, d) =>
{
// your custom logic
})
.AfterMap((s, d) =>
{
// your custom logic
});
}
}
One way of achieving this would be to create separate mapping engine instances for each scenario, that way you could configure different maps, as suggested in this answer from Jimmy Bogard on wanting to map a single type in different ways.
hmm... Thanks guys for the feedback. I took time to consider all answers and suggestions. None particularly renders exactly well though they provided a lot of food for thought. I thought I should inject something I tried. (Disclaimer: My opinion is that its a dirty approach - many things could go wrong - and Murphy's laws continue to hold). You could leverage the Ignore functionality in the particular instance to "suspend" the mapping. Typically, in a try and catch block as follows:
public Student[] GetStudents()
{
try
{ // Suspend/Ignore the mappings
// => SUSPEND CONFIGURATION MAPPINGS for Subjects, Activities and Clubs
Mapper.CreateMap<TableStudent, Student>()
.ForMember(dest => dest.Courses, opt => opt.Ignore())
.ForMember(dest => dest.Activities, opt => opt.Ignore())
.ForMember(dest => dest.Clubs, opt => opt.Ignore())
DataContext dbContext = new StudentDBContext();
var query = dbContext.Students;
// other logic ...
var students = Mapper.Map<Student>(query); // => Still be able to use AutoMapper to map other members
// set the properties you needed to do manually
}
finally // Restore back the mappings
{
Mapper.CreateMap<TableStudent, Student>()
.ForMember(dest => dest.Courses, opt => opt.MapFrom(src => Mapper.Map<IEnumerable<Course>>(src.TableCourses)))
.ForMember(dest => dest.Activities, opt => opt.MapFrom(src => Mapper.Map<IEnumerable<Activity>>(src.TableActivities)))
.ForMember(dest => dest.Clubs, opt => opt.MapFrom(src => Mapper.Map<IEnumerable<Clubs>>(src.TableClubs)))
}
}
Like I mentioned, its perhaps dirty. Not the kind of code I would be happy wriing - especially since I don't know what kind of exceptional situations can arise if CreateMap() fails within the finally block, but on a legacy application where you couldn't overhaul the approach - to possibly use different profiles like suggested by #AndriyZakharko above, you could use it to get control back temporarily. I tried it out personally.
Is it possible to ignore mapping a member depending on the value of a source property?
For example if we have:
public class Car
{
public int Id { get; set; }
public string Code { get; set; }
}
public class CarViewModel
{
public int Id { get; set; }
public string Code { get; set; }
}
I'm looking for something like
Mapper.CreateMap<CarViewModel, Car>()
.ForMember(dest => dest.Code,
opt => opt.Ignore().If(source => source.Id == 0))
So far the only solution I have is too use two different view models and create different mappings for each one.
The Ignore() feature is strictly for members you never map, as these members are also skipped in configuration validation. I checked a couple of options, but it doesn't look like things like a custom value resolver will do the trick.
Use the Condition() feature to map the member when the condition is true:
Mapper.CreateMap<CarViewModel, Car>()
.ForMember(dest => dest.Code, opt => opt.Condition(source => source.Id != 0))
I ran into a similar issue, and while this will overwrite the existing value for dest.Code with null, it might be helpful as a starting point:
AutoMapper.Mapper.CreateMap().ForMember(dest => dest.Code,config => config.MapFrom(source => source.Id != 0 ? null : source.Code));
Here is the documentation of the conditional mapping:
http://docs.automapper.org/en/latest/Conditional-mapping.html
There's also another method called PreCondition very useful on certain scenarios since it runs before the source value is resolved in the mapping process:
Mapper.PreCondition<CarViewModel, Car>()
.ForMember(dest => dest.Code, opt => opt.Condition(source => source.Id == 0))