Allow specifying type of field for parameters

[petrsvihlik]

Motivation

new OrderParameter($"elements.{Article.PublishDateCodename}", SortOrder.Descending)) is not very nice.

It would be great if OrderParameter (and perhaps some others) allowed specifying the type of the codename parameter.

Proposed solution

new OrderParameter(FieldType.Element, "Article.PublishDateCodename", SortOrder.Descending))

The enum could be defined such as:

enum FieldTypeEnum
{
 Element,
 System,
....
}

Originally reported in kontent-ai/delivery-sdk-net#241 (comment)

[pokornyd]

This is partially addressed in the modernized SDK (v19, vnext branch).

Filtering — fully typed

The Where clause now uses a fluent IItemsFilterBuilder with explicit System() and Element() methods, eliminating the need for manual string formatting:

// Old SDK — manual string interpolation
new EqualsFilter($"elements.{Article.PublishDateCodename}", "2024-01-01")

// New SDK — typed field selection
var result = await client.GetItems<Article>()
    .Where(f => f
        .Element(Article.PublishDateCodename).GreaterThan("2024-01-01")
        .System("collection").IsEqualTo("blog"))
    .ExecuteAsync();

The Element() method automatically prefixes with elements. and System() with system. — so there's no ambiguity about what kind of field you're referencing.

Ordering — still uses raw strings

The OrderBy method currently takes a raw path string:

.OrderBy("elements.publish_date", OrderingMode.Descending)
.OrderBy("system.last_modified", OrderingMode.Ascending)

This hasn't been given the same typed treatment as filtering. You can use the const codenames, but still need the elements. prefix:

.OrderBy($"elements.{Article.PostDateCodename}", OrderingMode.Descending)

Adding OrderByElement / OrderBySystem overloads would eliminate that and be consistent with the filtering API design. I'll consider this for a future update.

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The SDK is currently pre-released as 19.0.0-rc3, with production release planned for early April. It's compatible with the latest beta of model generator. Sync API features are newly released as a standalone SDK.