I am building a service using ServiceStack and using OrmLite to communicate with database. I found following example in ServiceStack OrmLite Documention:
db.Select<Author>(q => q.Earnings <= 50);
OR
db.Select<Author>(q => q.Name.StartsWith("A"));
I am trying it with my class User, but unable to find a overload for method "Select" which allows me to do mentioned stuff. In my case q is a linq expression not an instance/reference for generic class type (User in my case). Following is my code:
db.Select<User>(q => q.Where(x => x.LastName == "XYZ"));
and i want it to be like:
db.Select<User>(q => q.LastName == "XYZ");
Please let me know if that is an extension method which i am looking for and how can i use that?
The Type that gets selected is the table is looking at, e.g:
db.Select<Author>(...) //Author
db.Select<User>(...) //User
See the answers on this earlier question for selecting a subset of data with OrmLite.
Related
I have written a piece of software that parses and formats the fourth parameter of a graphql resolver function (the info object) to be used elsewhere. I would like to write unit tests for this software. Specifically, I do not want to build the GraphQLResolveInfo object myself, because doing that would be very cumbersome, error-prone and hard to maintain. Instead, I want to write human-readable query strings and convert them to GraphQLResolveInfo objects so I can pass those to my software.
After extensive googling and reading of the graphql-js source code, I have not found a simple way to do what they are doing internally. I'm really hoping that I am missing something.
What I am not trying to do is use the graphql-tag library, because that just generates an AST which has a very different format from the GraphQLResolveInfo type.
Has anyone done this before? Help would be much appreciated!
I will keep monitoring this question to see if a better answer comes along, but I've finally managed to solve my particular issue by creating as close an approximation of the GraphQLResolveInfo object as I need for my particular use case.
The GraphQLResolveInfo object is composed of several attributes, two of which are called fieldNodes and fragments. Both are in fact parts of the same AST that graphql-tag generates from a query string. These are the only parts of the GraphQLResolveInfo object that concern the software I wrote, the rest of it is ignored.
So here is what I did:
import gql from 'graphql-tag';
// The converter function
const convertQueryToResolveInfo = (query) => {
const operation = query.definitions
.find(({ kind }) => kind === 'OperationDefinition');
const fragments = query.definitions
.filter(({ kind }) => kind === 'FragmentDefinition')
.reduce((result, current) => ({
...result,
[current.name.value]: current,
}), {});
return {
fieldNodes: operation.selectionSet.selections,
fragments,
};
};
// An example call
const query = gql`
query {
foo {
bar
}
}
`;
const info = convertQueryToResolveInfo(query);
From the AST generated by graphql-tag, I extract and modify the operation and fragment definitions so that they look the way they do within the GraphQLResolveInfo object. This is by no means perfect and may be subject to change in the future depending on how my software evolves, but it is a relatively brief solution for my particular problem.
I have an ASP .Net core application. I am simply trying to have my AutoMapper configure to convert a string comma delimited into a list of strings as per this configuration:
configuration.CreateMap<Job, JobDto>()
.ForMember(dto => dto.Keywords, options => options.MapFrom(entity => entity.Keywords.Split(',').ToList()))
For some reason it does not get compiled and give me the following error:
An expression tree may not contain a call or invocation that uses
optional argument
I can't see why I am getting this error. I am pretty sure that I have done that in my other projects before without any such error.
As error says, Split function has an optional parameter. The full signature of it is as this (options is optional)
public string[] Split(string separator, StringSplitOptions options = StringSplitOptions.None)
As you are trying to use a function with default value inside an expression tree, it gives you the error.
To Fix it, easy, just pass on optional parameters by yourself. ( StringSplitOptions.None )
So, simply change it to this:
entity.Keywords.Split(',' , StringSplitOptions.None).ToList()
This is completely true.
Error is raised because expression tree being created is about to contain some more complex logic, like .Split(',').ToList(), which is not an accessible property or method, only top-level reflected object properties and methods are supported (like in class MemberInfo).
Property chaining, deep-calls (.obj1property.obj2property), extension methods are not supported by the expression trees, like in this .ToList() call.
My solution was like this:
// Execute a custom function to the source and/or destination types after member mapping
configuration.CreateMap<Job, JobDto>()
.AfterMap((dto,jobDto)=>jobDto.Keywords = dto.Keywords.Split(',').ToList());
I had the same problem. I do not know if it is an issue or not. Anyway, I found a workaround.
CreateMap<Category, GetCategoryRest>()
.ForMember(dest => dest.Words,
opt => opt.MapFrom(src => ToWordsList(src.Words)));
private static List<string> ToWordsList(string words)
{
return string.IsNullOrWhiteSpace(words) ? new List<string>() : words.Split(",").ToList();
}
It is guaranteed that AutoMapper has always a List. Still, I'm confused. In my Startup.cs I define that AutoMapper allows null values for list.
Mapper.Initialize(cfg => {
cfg.AllowNullCollections = true;
}
Category.Words is a string.
GetCategoryRest.Words is a List<string>
AutoMapper Version: 8.1.1,
AutoMapper.Microsoft.DependencyInjection: 6.1.1
Use .AfterMap
CreateMap<src, dto>()
.ForMember(src =>src.Categories,options=> options.Ignore())
.AfterMap((src, dto) => { dto.Categories.AddRange(src.Categories.Split(",").ToList()); })
.ReverseMap()
.ForMember(src => src.Categories, option => option.MapFrom(dto => string.Join(",", dto.Categories)));
I'm using AutoMapper 5.2. I currently have a mapping statement that looks as follows:
CreateMap<JeffreysOnline.Data.Customer, JeffreysOnline.Entities.Customer>()
.ForMember(s => s.CustomerWant, t => t.Ignore());
Both the Customer table and Customer entity have a field named BadChecks. In the database it's an int. I recently changed the type to a bool in my entity. AutoMapper is now giving me the following error:
Unable to create a map expression from Customer.BadChecks (System.Int16) to Customer.BadChecks (System.Boolean) Mapping types: Customer -> Customer JeffreysOnline.Data.Customer -> JeffreysOnline.Entities.Customer Type Map configuration: Customer -> Customer JeffreysOnline.Data.Customer -> JeffreysOnline.Entities.Customer Property: BadChecks
It seems AutoMapper doesn't know how to map from an int to a boolean. Is it possible for me to help AutoMapper with this?
It may be helpful to know that in my DAL, I'm using ProjectTo() to pass an IQueryable to another method that is attempting to access the data, and therefore the mapping is occurring (an error being generated). My DAL code looks like this:
return entityList.OrderBy(row => row.LastName).ProjectTo<Entities.Customer>();
Automapper 6.0.2 - works without any ForMember... null, 0 = false, values >= 1 are mapped to true.
In Automapper 6.0.2 - other way:
class nnnProfile : Profile
{
CreateMap<src, dst>()
.ForMember(d => d.Decision, opt => opt.ResolveUsing<CustomBoolResolver>());
}
Resolver:
public class CustomBoolResolver : IValueResolver<src, dst, bool>
{
public bool Resolve(src source, dst destination, bool destMember,
ResolutionContext context)
{
return source.Decision == 1;
}
}
but this is per Destination, so not much flexible.
According to this page:
http://taswar.zeytinsoft.com/automapper-mapping-objects-part-5-of-7-customresolver/
In past you could write a custom resolver with just Source and target type.
I don't think I would know how to map from int to a boolean.
If you do figure out how that should happen, you'll need to create a mapping from int to boolean.:
CreateMap<int, bool>().ProjectUsing(src => src != 0);
Completely guessing there. But since you're using ProjectTo, you'll need to use ProjectUsing so that the expression makes it allllll the way down to your DAL.
Remember, when using ProjectUsing, AutoMapper isn't actually executing the mapping. It's creating a LINQ "Select" expression that it passes down to your query provider (EF maybe?). So you'll need to make sure that whatever you use in your projection expression, EF can support translating that eventually into SQL.
I want to customise the way AutoMapper converts my types without losing the features already implemented by AutoMapper.
I could create a custom ITypeConverter instance but I can't see how to invoke the default behaviour.
Mapper.CreateMap<MyDomainObject, MyDto>
.ConvertUsing<MyTypeConverter>();
...
public class MyTypeConverter : TypeConverter<MyDomainObject, MyDto>
{
public MyDto ConvertCore(MyDomainObject source)
{
var result = // Do the default mapping.
// do my custom logic
return result
}
}
If I try to call var result = Mapper.Map<MyDto>(source) it gets into an infinite loop. I effectively want AutoMapper to do everything it normally would assuming there was no TypeConverter defined.
Any help greatly appreciated.
If you only want to customise some values on the destination object, then you're better off with a Custom Value Resolver - TypeConverters are designed to handle the whole conversion.
The doc page listed above will have enough to get you started: when you have implemented the CustomResolver you apply it like this, and AutoMapper will do the default mapping for the other properties:
Mapper.CreateMap<MyDomainObject, MyDto>()
.ForMember(dest => dest.TargetProperty,
opt => opt.ResolveUsing<CustomResolver>());
Using Entity Framework 4.3 in one of my data access classes I have generic a function like this
public List<Company> Query(Func<Company, bool> expression)
{
return MyDbContext.Instance().Company.Where(expression).ToList();
}
I use it from the bussines layer classes as MyDAL.Query(a => a.Name.Contains(textToSearch)).
Despite ofEntity Framework return the correct results, I don't know why it instead of generate a Sql query sentence with Where clause like "Where name like '%' + textToSearch + '%'", It generates a sql query sentence without a where clause query all the table rows. Obviously this is very inneficient.
By the other way if in my data access clases I write a method like this:
public List<Company> GetLikeName(string textToSearch)
{
return MyDbContext.Instance().Company.Where(a => a.Contains(textToSearch)).ToList();
}
It generates correctly a Sql with where like clause.
Why If I use my generic query to retrieve results from database especifying the expression to query from my bussiness classes it generates a Sql sentence without where clause?
Thanks
You need to pass the expression parameter as an Expression<>:
public List<Company> Query(Expression<Func<Company, bool>> expression)
If you just pass a Func<>, then IEnumerable.Where is called instead of IQueryable.Where, and it runs in code, not in SQL.