Handling queries over related documents in RavenDB - ravendb

Question

I have a project where I have a set of forms:
public class Form
{
public string Id { get; set; }
public string Name { get; set; }
public IList<string> FieldValueIds { get; set; }
public string UserId { get; set; } // the user who completed the form.
public string FormTemplateId { get; set; }
}
Which each "implement" a form template selected at creation of the form.
public class FormTemplate
{
public string Id { get; set; }
public string Name { get; set; }
public IList<string> FieldIds { get; set; }
}
Which defines which fields are present within the form. Each field
public class FormField
{
public string Id { get; set; }
public string Name { get; set; }
public string Caption { get; set; }
public ValueType DataType { get; set; } // Enum specifying the type of data this field accepts.
}
Stores information about the field such as a description and what type it is expecting. Each FormField can be present in multiple FormTemplates with the values for the form being stored as FieldValue objects related to the Form itself.
public class FieldValue
{
public string Id { get; set; }
public string FieldId { get; set; }
public string ValueAsJsonString { get; set; }
}
Other objects include the User Object:
public class User
{
public string Id { get; set; }
public string Username { get; set; }
public string GivenNames { get; set; }
public string Surname { get; set; }
}
I would like to be able to perform a query to find all Forms completed by a user with a specified name, or all Forms where a field with name X has value Y and so forth.
I have looked into usage of indexes as specified in the documentation Indexing related documents, however the implementation as presented in the documentation threw a NotSupportedException when I implemented the example as follows:
class FormTemplates_ByFieldAndName : AbstractIndexCreationTask<FormTemplate>
{
public class Result
{
public string Name { get; set; }
public IList<string> FieldNames { get; set; }
}
public FormTemplates_ByFieldAndName()
{
Map = FormTemplates => from FormTemplate in FormTemplates
select new
{
Name = FormTemplate.Name,
FieldNames = FormTemplate.FieldIds.Select(x => LoadDocument<FormField>(x).Name)
};
}
}
// in code:
IList<FormTemplate> TestResults = session.Query<FormTemplates_ByFieldAndName.Result, FormTemplates_ByFieldAndName>()
.Where(x => x.Name == "TemplateName" || x.FieldNames.Contains("FieldName"))
.OfType<FormTemplate>()
.ToList();
As best as I can tell this was implemented correctly, however I have seen a suggestion to replace the .Contains with a .Any implementation instead. In lieu of this I have been experimenting with a different approach by applying successive .Where arguments. Like so:
var pre = session.Query<FormTemplates_ByFieldAndName.Result, FormTemplates_ByFieldAndName>();
var pr2 = pre.Where(x => x.Name == "TypeTest25");
List<FormTemplate> TestResults = pr2
.Where(x => x.FieldNames.Any(a => a == "field25"))
.OfType<FormTemplate>()
.OrderByScoreDescending()
.ToList();
Modifying the system to perform in a more factory oriented approach by applying successive filters based on a supplied string in a pre-specified format.
Is this the way I should be going for this implementation and if not what should I be changing? In particular if I am to proceed with the Indexing option how would I apply this technique to the nested relationship between Forms and FormFields through FormTemplates.

Answer 1

You seems to be trying to do this in a way that is mostly relational, but you don't have to.
Instead of trying to have a set of independent documents that each has part of the data, just store it all in a single document.
public class Form
{
public string Id { get; set; }
public string Name { get; set; }
public IList<FieldValue> FieldValues { get; set; }
public string UserId { get; set; } // the user who completed the form.
public string FormTemplateId { get; set; }
}
public class FieldValue
{
public string Id { get; set; }
// can store the value directly!
//public string ValueAsJsonString { get; set; }
public object Value {get; set; }
}
This will generate documents that looks like this:
{
"Id": "forms/1234",
"Name": "Tom",
"FieldValues": [
{
"Id": "FromValues/SchoolDistrictName",
"Value": "ABi195"
}
],
"UserId": "users/tom",
"FormTemplateId": "FromTemplate/1234"
}
Which is a much more natural way to model things.
At that point, you can use RavenDB's ability to index dynamic data, see the docs here:
https://ravendb.net/docs/article-page/3.5/Csharp/indexes/using-dynamic-fields