JSON string array into Entity Framework - json

Question

I'm trying to get a JSON file into a SQL Server database with auto identity keys and the correct foreign key relation. Everything is working gloriously with the exception of a string array. The data looks more or less like this:
{
"id" : "123",
"name" : "Some Stuff",
"phrase" : "More Stuff",
"type" : "ABC",
"label" : "Some label",
"responseType" : "The Response Type",
"answers" : [ "9" ]
}
The "answers" part is causing me fits. It looks like it's almost exclusively a single value, but it could potentially have multiple values like
"answers" : [ "6", "7", "8" ]
Now I know that a List is not supported in EF for native types like string or int. I ultimately would rather have a separate table for the list of answer values anyway, which I'm calling DataAnswers.
public partial class Response
{
[Key]
[DatabaseGenerated(DatabaseGeneratedOption.Identity)]
public int ResponseId { get; set; }
[JsonProperty("id", NullValueHandling = NullValueHandling.Ignore)]
public string Id { get; set; }
[JsonProperty("name", NullValueHandling = NullValueHandling.Ignore)]
public string Name { get; set; }
[JsonProperty("phrase", NullValueHandling = NullValueHandling.Ignore)]
public string Phrase { get; set; }
[JsonProperty("type", NullValueHandling = NullValueHandling.Ignore)]
public string Type { get; set; }
[JsonProperty("label", NullValueHandling = NullValueHandling.Ignore)]
public string Label { get; set; }
[JsonProperty("responseType", NullValueHandling = NullValueHandling.Ignore)]
public string ResponseType { get; set; }
[JsonProperty("answers", NullValueHandling = NullValueHandling.Ignore)]
public virtual List<DataAnswer> DataAnswers { get; set; }
}
public partial class DataAnswer
{
[Key]
[DatabaseGenerated(DatabaseGeneratedOption.Identity)]
public int DataAnswerId { get; set; }
public string AnswerText { get; set; }
}
Currently here's the error I'm getting.
Newtonsoft.Json.JsonSerializationException: 'Error converting value
"9" to type 'ForeseeDemo.Data.DataAnswer'. Path
'items[0].responses[0].answers[0]', line 60, position 23.'
Any great ideas of how to get a list of answer strings into a table with a foreign key to the Response ?
Thanks in advance!

Answer 1

You could create a data transfer object then handle the conversion b/t that and the entity object.
You could create a custom JSON converter to handle conversion of the property.
You could create an additional property that is used for serialization/deserialization but not by EF and handle conversions there:
[JsonIgnore]
public virtual List<DataAnswer> DataAnswers { get; set; }
[NotMapped]
[JsonProperty( "answers", NullValueHandling = NullValueHandling.Ignore )]
public List<string> DataAnswerStrings
{
get => DataAnswers?.Select( da => da.AnswerText )?.ToList();
set => DataAnswers = value
?.Select( s => new DataAnswer() { AnswerText = s } )
?.ToList()
?? new List<DataAnswer>();
}