CODEWITHSUNDEEP
c#.netclasselasticsearchnest
GWilkinson
GWilkinson

Reputation: 107

Providing null value for elasticsearch date field

I just wanted to know if anyone knows how to provide a null value for an elasticsearch date field.

You can see in the screenshot below that it is possible to utilise a DateTime for the null value but when I try it doesn't accept it. Producing the error message:

"'NullValue' is not a valid named attribute argument brecause it is not a valid attribute parameter type."

Date field options

Upvotes: 0

Views: 4612

Answers (2)

Russ Cam
Russ Cam

Reputation: 125488

Because NullValue for DateAttribute is a DateTime, it can't be set on a attribute applied to a POCO property because the set value would need to be a compile time constant. This is one of the limitations of going with the attribute approach to mapping.

NullValue can be set in a couple of ways:

Using the fluent API

The fluent mapping can do everything that attribute mapping can do, as well as handle functionality such as null values, multi_fields, etc.

public class MyDocument
{
    public DateTime DateOfBirth { get; set; }
}

var fluentMappingResponse = client.Map<MyDocument>(m => m
    .Index("index-name")
    .AutoMap()
    .Properties(p => p
        .Date(d => d
            .Name(n => n.DateOfBirth)
            .NullValue(new DateTime(1970, 1, 1, 0, 0, 0, DateTimeKind.Utc))
        )
    )
);

Using a visitor pattern

Define a visitor that will visit all the properties in the POCO, and use this to set a null value. The visitor pattern is useful for applying conventions to your mapping, for example, all string properties should be a multi_field with a not analyzed raw sub field.

public class MyPropertyVisitor : NoopPropertyVisitor
{
    public override void Visit(IDateProperty type, PropertyInfo propertyInfo, ElasticsearchPropertyAttributeBase attribute)
    {
        if (propertyInfo.DeclaringType == typeof(MyDocument) &&
            propertyInfo.Name == nameof(MyDocument.DateOfBirth))
        {
            type.NullValue = new DateTime(1970, 1, 1, 0, 0, 0, DateTimeKind.Utc);
        }
    }
}

var visitorMappingResponse = client.Map<MyDocument>(m => m
    .Index("index-name")
    .AutoMap(new MyPropertyVisitor())
);

both the fluent mapping and visitor produce the following request

{
  "properties": {
    "dateOfBirth": {
      "null_value": "1970-01-01T00:00:00Z",
      "type": "date"
    }
  }
}

Take a look at the automapping documentation for more information.

Upvotes: 4

GWilkinson
GWilkinson

Reputation: 107

Just used the following code instead of declaring it on the class date attribute:

.Properties(pr => pr
  .Date(dt => dt
    .Name(n => n.dateOfBirth)
    .NullValue(new DateTime(0001, 01, 01))))

Upvotes: 0

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