I got a custom ValueConverter that serializes objects as JSON and stores them as a STRING in the database. This works well, but for some use cases I need to read the data as it is in the database, ignoring the ValueConverter. How to do that?
Unfortunatly, the API of a ValueConverter does not allow to disable a conversion, because my implementation has to return a value of type object and can't return a STRING.
I found this answer that is applicable to my problem. Use a projection and cast the property to its database type (STRINGin this example).
EmployeeSet.Select(e => new {Name = e.Name, RawData = (string)e.Data})
Related
How can I serialize the field name with a different name from what is defined in the Document object?
from elasticsearch_dsl import Document, Text
class MyDocument(Document):
context = Text()
When saving this document to ES, I want to write the 'context' key as '#context'.
Since #context is not a valid python identifier I am afraid this is not easily possible. You can always drop down to the raw json (by overriding the to_dict method) but I would definitely not recommend it.
I am having issues saving my entity that has a Instant value using the NamedJdbcTemplate. I receive the exception listed below and I am trying to determine the best way to resolve this. Please advise.
Can't infer the SQL type to use for an instance of java.time.Instant. Use setObject() with an explicit Types value to specify the type to use.
I am using the postgresql:9.4.1212 driver
This code worked for me:
Instant ts = // whatever instant
MapSqlParameterSource params = new MapSqlParameterSource();
params.addValue("ts", Timestamp.from(ts), Types.TIMESTAMP);
jdbcTemplate.queryForList(SQL, params)
where SQL is the parametrized query and make sure you're using java.sql.Timestamp and java.sql.Types.
I know that MongoDb C# driver doesn't support projections so I searched a little bit and I found that many people uses a mongoCursor to perform such queries, I'm trying to select only specific fields and my code is the following:
public T GetSingle<T>(Expression<Func<T, bool>> criteria,params Expression<Func<T, object>>[] fields) where T : class
{
Collection = GetCollection<T>();
return Collection.FindAs<T>(Query<T>.Where(criteria)).SetFields(Fields<T>.Include(fields)).SetLimit(1).SingleOrDefault();
}
I got and custom repository for users on top of that:
public User GetByEmail(string mail, params Expression<Func<User, object>>[] fields)
{
return GetSingle<User>(x=>x.Email==mail,fields);
}
this is the usage:
_repository.GetByEmail(email, x=>x.Id,x=>x.DisplayName,x=>x.ProfilePicture)
but I'm getting the fields included in the parameter but also all the Enums,dates and Boolean values that are part of the class User, the values that are string and not included in the field list are null so that's fine
what can I do to avoid that?
By using SetFields, you can specify what goes through the wire. However, you're still asking the driver to return hydrated objects of type T, User in this case.
Now, similar to say an int, enum and boolean are value types, so their value can't be null. So this is strictly a C#-problem: there is simply no value for these properties to indicate that they don't exist. Instead, they assume a default value (e.g. false for bool and 0 for numeric types). A string, on the other hand, is a reference type so it can be null.
Strategies
Make the properties nullable You can use nullable fields in your models, e.g.:
class User {
public bool? GetMailNotifications { get; set; }
}
That way, the value type can have one of its valid values or be null. This can, however, be clumsy to work with because you'll have to do null checks and use myUser.GetMailNotifications.Value or the myUser.GetMailNotifications.GetValueOrDefault helper whenever you want to access the property.
Simply include the fields instead this doesn't answer the question of how to it, but there are at least three good reasons why it's a good idea to include them:
When passing a User object around, it's desirable that the object is in a valid state. Otherwise, you might pass a partially hydrated object to a method which passes it further and at some point, someone attempts an operation that doesn't make sense because the object is incomplete
It's easier to use
The performance benefit is negligible, unless you're embedding huge arrays which I would suggest to refrain from anyway and which isn't the case here.
So the question is: why do you want to make all the effort of excluding certain fields?
I can successfully return a model from my controller like this:
return View(lemonadedb.Messages.ToList() );
It's interpreted perfectly by my view.
Now I only want to show the messages where Messages.user == Membership.GetUser().ToString().
But when I do this:
return View(lemonadedb.Messages.Where( p => p.user == Membership.GetUser().ToString()).ToList());
I get:
'LINQ to Entities does not recognize
the method 'System.String ToString()'
method, and this method cannot be
translated into a store expression.'
I need some way to narrow down the results of the messages table.
Should I use the find() method somehow? I thought it was only for ID's.
How should I do this?
The reason you're having this issue is that Entity Framework is trying to evaluate the expression Membership.GetUser().ToString() into an SQL query. You need to create a new variable to store the value of this expression and pass it into your query. Entity Framework will then just interpret this as you expect.
The following should work:
var user = Membership.GetUser().ToString();
return View(lemonadedb.Messages.Where(p => p.user == user).ToList());
I suspect this is a very common mistake that people make when writing Entity Framework queries.
I'm trying to integrate NHibernate.Validator with ASP.NET MVC client side validations, and the only problem I found is that I simply can't convert the non-interpolated message to a human-readable one. I thought this would be an easy task, but turned out to be the hardest part of the client-side validation. The main problem is that because it's not server-side, I actually only need the validation attributes that are being used, and I don't actually have an instance or anything else at hand.
Here are some excerpts from what I've been already trying:
// Get the the default Message Interpolator from the Engine
IMessageInterpolator interp = _engine.Interpolator;
if (interp == null)
{
// It is null?? Oh, try to create a new one
interp = new NHibernate.Validator.Interpolator.DefaultMessageInterpolator();
}
// We need an instance of the object that needs to be validated, se we have to create one
object instance = Activator.CreateInstance(Metadata.ContainerType);
// we enumerate all attributes of the property. For example we have found a PatternAttribute
var a = attr as PatternAttribute;
// it seems that the default message interpolator doesn't work, unless initialized
if (interp is NHibernate.Validator.Interpolator.DefaultMessageInterpolator)
{
(interp as NHibernate.Validator.Interpolator.DefaultMessageInterpolator).Initialize(a);
}
// but even after it is initialized the following will throw a NullReferenceException, although all of the parameters are specified, and they are not null (except for the properties of the instance, which are all null, but this can't be changed)
var message = interp.Interpolate(new InterpolationInfo(Metadata.ContainerType, instance, PropertyName, a, interp, a.Message));
I know that the above is a fairly complex code for a seemingly simple question, but I'm still stuck without solution. Is there any way to get the interpolated string out of NHValidator?
Ok, so I know this is an old question, but I stumbled across this when trying to do the same thing, and it helped me get started - so I thought I would provide an answer.
I think the code in the question was on the right track but there are a couple of problems. The interpolator was not completely initialised with the ResourceManager and Culture details, and it doesn't seem to allow for the fact that you can only have one DefaultMessageInterpolator per validation attribute. Also, you don't need an instance of the object you are validating to get an interpolated message.
In the code in the question, where you are initialising the interpolator with the attribute value, you also need to initialise the interpolator with details of the ResourceManager to be used.
This can be done using the overloaded Initialize method on DefaultMessageInterpolator which has the following signature:
public void Initialize(ResourceManager messageBundle,
ResourceManager defaultMessageBundle,
CultureInfo culture)
The first parameter is a user-defined ResourceManager in case you want to use your own resource file for error messages, you can pass a null if you just want to use the default ResouceManager, the second parameter is the default ResourceManager - you can pass
new ResourceManager(
NHibernate.Validator.Cfg.Environment.BaseNameOfMessageResource,
Assembly.GetExecutingAssembly());
for this, the last parameter is the culture to use, (NHibernate.Validator comes with resource files with validation messages in several languages) - if you pass a null in to this it will just use CultureInfo.CurrentCulture
Lastly, you can only have one DefaultMessageInterpolator per attribute, so you will need to create a new DefaultMessageInterpolator for each validation attribute. You could make use of the DefaultMessageInterpolatorAggregator to handle this, or just roll your own.
I hope this helps someone.
Thanks for your help all--I'd upvote if I could. I just wanted to add that in addition to the first Initialize call on the DefaultMessageInterpolator that Stank illustrates, I also had to make a second different Initialize call to fully initialize it (I was getting some Null Reference Exceptions using only the first call). My code is as follows:
string interpolatedMessage = "";
DefaultMessageInterpolator interpolator = new DefaultMessageInterpolator();
interpolator.Initialize(null,
new ResourceManager(
NHibernate.Validator.Cfg.Environment.BaseNameOfMessageResource,
Assembly.Load("NHibernate.Validator")),
CultureInfo.CurrentCulture);
interpolator.Initialize(attribute as Attribute);
if (attribute is IValidator && attribute is IRuleArgs)
{
IValidator validator = attribute as IValidator;
IRuleArgs ruleArgs = attribute as IRuleArgs;
InterpolationInfo interpolationInfo = new InterpolationInfo(
validatableType,
null,
propertyName,
validator,
interpolator,
ruleArgs.Message);
interpolatedMessage = interpolator.Interpolate(interpolationInfo);
}