Serialization attributes on TableEntity in Azure Table Storage - asp.net-web-api

Im using web API to return data in azure table storage. Im returning a class that I 'm inheriting TableEntity in a class and adding properties but want to keep to the .Net convention of capitalized property names but also keep to the JavaScript/json convention of lowercase properties names.
I've tried adding the Json.net property attributes to the class but it appears to be ignored. E.g.:
[JsonProperty("id")]
public string ID {get;set;}
If the instance has a value set on ID, null is represent in the serialized result.

According to your description, I tested this issue on my side and found it works well on my side and Azure. Here is my detailed steps, you could refer to it.
Create a controller named UserInfoController in the Web API application with the Get function like this:
// GET: api/UserInfo
[HttpGet]
public async Task<string> Get()
{
CloudStorageAccount storageAccount = CloudStorageAccount.Parse(<your-Storage-ConnectionString>);
CloudTableClient tableClient = storageAccount.CreateCloudTableClient();
CloudTable cloudTable = tableClient.GetTableReference("UserInfo");
TableQuery<User> query = new TableQuery<User>()
.Where(TableQuery.GenerateFilterCondition("PartitionKey", QueryComparisons.Equal, "Grade Four"));
var results =await cloudTable.ExecuteQuerySegmentedAsync(query, null);
//Serialize the object to string by using the latest stable version of Newtonsoft.Json
string jsonString = JsonConvert.SerializeObject(results);
return jsonString;
}
Entity
public class User : TableEntity
{
public User(string partitionKey, string rowKey)
{
this.PartitionKey = partitionKey;
this.RowKey = rowKey;
}
public User() { }
[JsonProperty("id")]
public long ID { get; set; }
[JsonProperty("username")]
public string UserName { get; set; }
[JsonProperty("phone")]
public string Phone { get; set; }
[JsonProperty("age")]
public int Age { get; set; }
}
Result
Deploy the Web API application to Azure, then you could find the following result by calling the function via Fiddler.
In summary, please try to check the version of Json.NET you are using. If you aren't using the latest (9.0.1), then please try to upgrade to the latest version and run your application again to find whether it could work as expected.

FYI - while this doesn't answer the direct answer of how to get TableEntity to respect JSON.net attributes... I was able to solve the use case by overriding the ReadEntity and WriteEntity method in the inherited class:
e.g.
public class User : TableEntity{
//Upper case name
public string Name {get; set};
public override void ReadEntity(IDictionary<string, AzureTableStorage.EntityProperty> properties, OperationContext operationContext){
base.ReadEntity(properties, operationContext);
//lower case
this.Name = properties["name"];
}

Related

Can't cast database type character to Guid

I updated my solution from .Net 3.1 to .Net 6. Also updated the Npgsql nuget package from 5.0.10 to 6.0.4 as part of this upgrade.
Since then, I am receiving an error "Can't cast database type character to Guid" when I try to retreive data from the database.
My mapping in the context file is
entity.Property(e => e.UserId).HasColumnName("user_id").HasColumnType("CHAR(36)");
In C# class, this property is a GUID.
Is there some mapping update with the newer version of npgsql?
EF Core has a built-in value converter which implicitly converts .NET Guid properties to text columns (see docs. Note that PostgreSQL has a full UUID type - that's a better way to store GUIDs in the database, rather than as text.
This works in EF Core 6.0.4 - if you're encountering trouble, please produce a minimal, runnable code sample and add it to your question above.
Working 6.0 code:
await using var ctx = new BlogContext();
await ctx.Database.EnsureDeletedAsync();
await ctx.Database.EnsureCreatedAsync();
ctx.Blogs.Add(new Blog { Guid = Guid.NewGuid()});
await ctx.SaveChangesAsync();
_ = await ctx.Blogs.ToListAsync();
public class BlogContext : DbContext
{
public DbSet<Blog> Blogs { get; set; }
protected override void OnConfiguring(DbContextOptionsBuilder optionsBuilder)
=> optionsBuilder
.UseNpgsql(#"Host=localhost;Username=test;Password=test")
.LogTo(Console.WriteLine, LogLevel.Information)
.EnableSensitiveDataLogging();
}
public class Blog
{
public int Id { get; set; }
public string Name { get; set; }
[Column(TypeName = "CHAR(36)")]
public Guid Guid { get; set; }
}

ASP.NET Web API - how to pass unknown number of form-encoded POST values

The front-end of my application can send unknown number of POST values inside a form. Fro example in some cases there will be 3 values coming from certain textboxes, in some cases there will be 6 values coming from textboxes, dropdowns etc. The backend is ASP.NET Web API. I know that a simple .NET value can be passed in URI parameter to a "POST Action" using FromURI attribute and a complex type can be passed in body and fetched using FromBody attribute, in any POST Action. But in my case the number of form data values will NOT be constant rather variable and I can't use a pre-defined class to hold values using 'FromBody' attribute.
How can I tackle this situation?
You can use the FormDataCollection from the System.Net.Http.Formatting namespace.
public class ApiFormsController : ApiController
{
[HttpPost]
public IHttpActionResult PostForm(FormDataCollection form)
{
NameValueCollection items = form.ReadAsNameValueCollection();
foreach (string key in items.AllKeys)
{
string name = key;
string val = items[key];
}
return Ok();
}
}
Try to send this properties as list of properties. Make model something like this:
public class PostModel
{
public IEnumerable<PropertyModel> Properties { get; set; }
}
public class PropertyModel
{
public string Value { get; set; }
public string Source { get; set; }
// etc.
}
And action:
public IHttpActionResult Post(PostModel model)
{
//Omited
return Ok();
}

Using Automapper to map object to realm object with Xamarin and c#

I am creating an Xamarin.iOS app and a Realm database.I would like to keep my POCO objects separate from my RealmObject so what I did was use a repository pattern and within the repository I tried to use AutoMapper to map the POCO to the RealmObject
e.g. (subset)
public class PlaceRepository : IPlaceRepository
{
private Realm _realm;
public PlaceRepository(RealmConfiguration config)
{
_realm = Realm.GetInstance(config);
}
public void Add(Place place)
{
using (var trans = _realm.BeginWrite())
{
var placeRealm = _realm.CreateObject<PlaceRealm>();
placeRealm = Mapper.Map<Place, PlaceRealm>(place);
trans.Commit();
}
}
So, if I debug my code everything maps OK and placeRealm is populated OK but when I commit nothing gets saved to the Realm db. The following is my RealmObject
public class PlaceRealm : RealmObject
{
[ObjectId]
public string Guid { get; set; }
public string Title { get; set; }
public string Notes { get; set; }
}
and this is my POCO Place
public class Place
{
public string Guid { get; set; }
public string Title { get; set; }
public string Notes { get; set; }
}
And AutoMapper is initialized like so:
Mapper.Initialize(cfg =>
{
cfg.CreateMap<Place, PlaceRealm>();
cfg.CreateMap<PlaceRealm, Place>();
});
All standard stuff. Has anyone else managed to get something similar working?
Your poco 'Place' is called 'PlaceRealm'. I suspect that is a typo. (made edit)
I suspect that Automapper is instantiating a new object overwriting your original 'placeRealm' object.
Perhaps you could try
Mapper.Map(place, placeRealm);
in place of your current mapping.
which should just copy the values to your already instatiated and tracked object.
(no need to store the return value).
You might also want to make explicit which properties (3) you are mapping as currently Automapper will map all including those in the base class.
On a side note, you may run into performance issues with Automapper. I found it to be the performance bottleneck in some apps. ExpressMapper is a nice alternative.

MetaData class for entityframework POCO

I am creating a meta data class for a POCO object. I am adding the "CSVColumn" (from LINQToCSV) attribute to the meta data class. But when I run the program, it couldn't find its attributes.
So I tested it using reflection,
Type t = typeof(Case);
PropertyInfo pi = t.GetProperty("ProviderId");
//bool isReadOnly = ReadOnlyAttribute.IsDefined(pi,typeof( ReadOnlyAttribute);
var attributes = pi.GetCustomAttributes(typeof(Case),true);
It acutally return nothing by calling the "GetCustomAttributes".
What have I done wrong??
Below is the way I created metadata class.
One thing I don't understand is, it works perfectly well with MVC validations. Wondering how does that retrieve the custom attributes???
This is the entityframework POCO object
public partial class Case
{
public string ProviderName { get; set; }
public string ProviderId { get; set; }
}
Here I create a partial class of Case and metadata classes,
[MetadataType(typeof(CaseMetaData))]
public partial class Case
{
public class CaseMetaData
{
[CsvColumn(Name = "ProviderName", FieldIndex = 1)]
public string ProviderName { get; set; }
[CsvColumn(Name = "ProviderID", FieldIndex = 2)]
public string ProviderId { get; set; }
}
}
Please someone can help me, much appreciated.
Cheers
typeof(Case) isn't an attribute type.
You mean typeof(CsvColumnAttribute).
Also, standard Reflection isn't aware of metadata classes.
You need to use AssociatedMetadataTypeTypeDescriptionProvider.
A good example can be found here

Custom model validation of dependent properties using Data Annotations

Since now I've used the excellent FluentValidation
library to validate my model classes. In web applications I use it in conjunction with the jquery.validate plugin to perform client side validation as well.
One drawback is that much of the validation logic is repeated on the client side and is no longer centralized at a single place.
For this reason I'm looking for an alternative. There are many examples out there showing the usage of data annotations to perform model validation. It looks very promising.
One thing I couldn't find out is how to validate a property that depends on another property value.
Let's take for example the following model:
public class Event
{
[Required]
public DateTime? StartDate { get; set; }
[Required]
public DateTime? EndDate { get; set; }
}
I would like to ensure that EndDate is greater than StartDate. I could write a custom
validation attribute extending ValidationAttribute in order to perform custom validation logic. Unfortunately I couldn't find a way to obtain the
model instance:
public class CustomValidationAttribute : ValidationAttribute
{
public override bool IsValid(object value)
{
// value represents the property value on which this attribute is applied
// but how to obtain the object instance to which this property belongs?
return true;
}
}
I found that the CustomValidationAttribute seems to do the job because it has this ValidationContext property that contains the object instance being validated. Unfortunately this attribute has been added only in .NET 4.0. So my question is: can I achieve the same functionality in .NET 3.5 SP1?
UPDATE:
It seems that FluentValidation already supports clientside validation and metadata in ASP.NET MVC 2.
Still it would be good to know though if data annotations could be used to validate dependent properties.
MVC2 comes with a sample "PropertiesMustMatchAttribute" that shows how to get DataAnnotations to work for you and it should work in both .NET 3.5 and .NET 4.0. That sample code looks like this:
[AttributeUsage(AttributeTargets.Class, AllowMultiple = true, Inherited = true)]
public sealed class PropertiesMustMatchAttribute : ValidationAttribute
{
private const string _defaultErrorMessage = "'{0}' and '{1}' do not match.";
private readonly object _typeId = new object();
public PropertiesMustMatchAttribute(string originalProperty, string confirmProperty)
: base(_defaultErrorMessage)
{
OriginalProperty = originalProperty;
ConfirmProperty = confirmProperty;
}
public string ConfirmProperty
{
get;
private set;
}
public string OriginalProperty
{
get;
private set;
}
public override object TypeId
{
get
{
return _typeId;
}
}
public override string FormatErrorMessage(string name)
{
return String.Format(CultureInfo.CurrentUICulture, ErrorMessageString,
OriginalProperty, ConfirmProperty);
}
public override bool IsValid(object value)
{
PropertyDescriptorCollection properties = TypeDescriptor.GetProperties(value);
object originalValue = properties.Find(OriginalProperty, true /* ignoreCase */).GetValue(value);
object confirmValue = properties.Find(ConfirmProperty, true /* ignoreCase */).GetValue(value);
return Object.Equals(originalValue, confirmValue);
}
}
When you use that attribute, rather than put it on a property of your model class, you put it on the class itself:
[PropertiesMustMatch("NewPassword", "ConfirmPassword", ErrorMessage = "The new password and confirmation password do not match.")]
public class ChangePasswordModel
{
public string NewPassword { get; set; }
public string ConfirmPassword { get; set; }
}
When "IsValid" gets called on your custom attribute, the whole model instance is passed to it so you can get the dependent property values that way. You could easily follow this pattern to create a date comparison attribute, or even a more general comparison attribute.
Brad Wilson has a good example on his blog showing how to add the client-side portion of the validation as well, though I'm not sure if that example will work in both .NET 3.5 and .NET 4.0.
I had this very problem and recently open sourced my solution:
http://foolproof.codeplex.com/
Foolproof's solution to the example above would be:
public class Event
{
[Required]
public DateTime? StartDate { get; set; }
[Required]
[GreaterThan("StartDate")]
public DateTime? EndDate { get; set; }
}
Instead of the PropertiesMustMatch the CompareAttribute that can be used in MVC3. According to this link http://devtrends.co.uk/blog/the-complete-guide-to-validation-in-asp.net-mvc-3-part-1:
public class RegisterModel
{
// skipped
[Required]
[ValidatePasswordLength]
[DataType(DataType.Password)]
[Display(Name = "Password")]
public string Password { get; set; }
[DataType(DataType.Password)]
[Display(Name = "Confirm password")]
[Compare("Password", ErrorMessage = "The password and confirmation do not match.")]
public string ConfirmPassword { get; set; }
}
CompareAttribute is a new, very useful validator that is not actually
part of
System.ComponentModel.DataAnnotations,
but has been added to the
System.Web.Mvc DLL by the team. Whilst
not particularly well named (the only
comparison it makes is to check for
equality, so perhaps EqualTo would be
more obvious), it is easy to see from
the usage that this validator checks
that the value of one property equals
the value of another property. You can
see from the code, that the attribute
takes in a string property which is
the name of the other property that
you are comparing. The classic usage
of this type of validator is what we
are using it for here: password
confirmation.
It took a little while since your question was asked, but if you still like metadata (at least sometimes), below there is yet another alternative solution, which allows you provide various logical expressions to the attributes:
[Required]
public DateTime? StartDate { get; set; }
[Required]
[AssertThat("StartDate != null && EndDate > StartDate")]
public DateTime? EndDate { get; set; }
It works for server as well as for client side. More details can be found here.
Because the methods of the DataAnnotations of .NET 3.5 don't allow you to supply the actual object validated or a validation context, you will have to do a bit of trickery to accomplish this. I must admit I'm not familiar with ASP.NET MVC, so I can't say how to do this exactly in conjunction with MCV, but you can try using a thread-static value to pass the argument itself. Here is an example with something that might work.
First create some sort of 'object scope' that allows you to pass objects around without having to pass them through the call stack:
public sealed class ContextScope : IDisposable
{
[ThreadStatic]
private static object currentContext;
public ContextScope(object context)
{
currentContext = context;
}
public static object CurrentContext
{
get { return context; }
}
public void Dispose()
{
currentContext = null;
}
}
Next, create your validator to use the ContextScope:
public class CustomValidationAttribute : ValidationAttribute
{
public override bool IsValid(object value)
{
Event e = (Event)ObjectContext.CurrentContext;
// validate event here.
}
}
And last but not least, ensure that the object is past around through the ContextScope:
Event eventToValidate = [....];
using (var scope new ContextScope(eventToValidate))
{
DataAnnotations.Validator.Validate(eventToValidate);
}
Is this useful?

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