C#•2mo ago

✅ Designing a configurable object in EF Core

Hi everyone! My goal is to have an object for a web project where you can configure the fields it has:

public class Structure {
   public int Id;
   public string Name;
   public Property[] Properties; // each value to show/edit
   public Structure[] Structures; // in the future, can also contain other Structure objects
}

public class Property<TValue> {
   public int Id;
   public string Name;
   public T Value;
}

public class Structure {
   public int Id;
   public string Name;
   public Property[] Properties; // each value to show/edit
   public Structure[] Structures; // in the future, can also contain other Structure objects
}

public class Property<TValue> {
   public int Id;
   public string Name;
   public T Value;
}

This would let me design a "Patient" object:

new Structure(Id:"1", Name:"Patient")

new Structure(Id:"1", Name:"Patient")

I could add properties:

var properties = {
  new Property<string> {Id = 1, Name = "Patient Name", Value = "John Doe"},
  new Property<string> {Id = 2, Name = "Patient Id", Value = "007"},
  new Property<DateTime> {Id = 3, Name = "Patient Birthday", Value = "2024-09-22"}
}

var properties = {
  new Property<string> {Id = 1, Name = "Patient Name", Value = "John Doe"},
  new Property<string> {Id = 2, Name = "Patient Id", Value = "007"},
  new Property<DateTime> {Id = 3, Name = "Patient Birthday", Value = "2024-09-22"}
}

What would be a good approach in EF Core to this? Table-Per-Hierarchy? How can I map the TValue generic properly?

15 Replies

Angius•2mo ago

Honestly, for the kind of "whatever lmao" data I recommend just using a JSON column

Jimmacle•2mo ago

yeah, you could do EAV too but json is probably better

Saiyanslayer•2mo ago

would a complex type be worth exploring? but i assumed it'd be messy since it's a generic and if i use json, I'll have to add a column for what the generic is? that way, we can convert from json? since deserializing needs a type

Jimmacle•2mo ago

it doesn't, you can deserialize json to a document/node strong typing/generics and runtime configurable structures aren't particularly compatible

Saiyanslayer•2mo ago

you mean to trasnlate the Json column into a JsonNode and grab the info from it?

var node = JsonNode.Parse(value);

var node = JsonNode.Parse(value);

I'm concerned because the types could be a bit complex, like a checkbox list type or one that contains multiple classes a dropdown menu type that contains a string array and an int index for the current selection

Jimmacle•2mo ago

you'll have to build support for representing those dynamically and safely in your application

Saiyanslayer•2mo ago

kk, will that make me regret doing it in the future, or is it manable? Maybe not the best way, but still works for small scale?

Jimmacle•2mo ago

i mean, it depends

Saiyanslayer•2mo ago

ie < 25 users

Jimmacle•2mo ago

if it is really a business requirement for it to be this flexible you kind of have no choice

Saiyanslayer•2mo ago

ok thanks. Is this overall how you'd approach it? The business need is bascially being able to make custom TODO lists the list header values are essentially set when the list is made, but the the to-do tasks have to handle diverse data types im not sure if I'm being clear enough

Jimmacle•2mo ago

yeah, you just have to find a method of abstraction that balances between providing that flexibility and being a maintenance nightmare for few users i'd probably lean towards being less flexible and adding support for new user data types as needed EF Core isn't really designed to work with a dynamic schema so your options are mostly things that don't involve user defined types changing the database structure

Saiyanslayer•2mo ago

right, which basically limit me to a json column from what I'm seeing, I'll need to have the json value have the info of what the json value (either enum or the class type) to construct the class again. for example, to convert json to a Checkbox[] value I'm thinking I'd have a field that returns the type Checbox[] that gets stored in the json string

Jimmacle•2mo ago

yeah, i'd have some way to define that particular type of checkbox set and then refer to its definition along with the value for any particular instance i wouldn't store the entire definition in each place that set of checkboxes is used, that would be redundant unless you don't plan for them to be reused

Saiyanslayer•2mo ago

i think i may need to keep them separate. If you change one instance of the object, doesn't affect the others.

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✅ Designing a configurable object in EF Core