Inconsistencies between `ResourceData.GetRaw...()` and `ResourceDiff.GetRaw...()`

[gdavison]

SDK version

github.com/hashicorp/terraform-plugin-sdk/v2 v2.20.0

Relevant provider source code

func ResourceEntityRecognizer() *schema.Resource {
	return &schema.Resource{
		...

		Schema: map[string]*schema.Schema{
			...
			"version_name": {
				Type:     schema.TypeString,
				Optional: true,
				Computed: true,
				DiffSuppressFunc: func(k, oldValue, newValue string, d *schema.ResourceData) bool {
					...
				},
			},
			...
		},

		CustomizeDiff: customdiff.All(
			...
			func(_ context.Context, diff *schema.ResourceDiff, _ interface{}) error {
				...
			},
		),
	}
}

Terraform Configuration Files

Before:

resource "aws_comprehend_entity_recognizer" "example" {
  version_name = "value"
  ...
}

After:

resource "aws_comprehend_entity_recognizer" "example" {
  version_name = ""
  ...
}

Expected Behavior

Setting version_name = "" will cause both ResourceData.GetRawConfig().GetAttr("version_name") and ResourceDiff.GetRawConfig().GetAttr("version_name") to have the value ""

Actual Behavior

In the CustomizeDiffFunc, ResourceDiff.GetRawConfig().GetAttr("version_name") has the value "value".

In the Update function, ResourceData.GetRawConfig().GetAttr("version_name") has the value "".

References

I assume this is related to how Optional & Computed do not show a diff.

[bflad]

My understanding with the old internals of the sdk is that the cty value handling (Raw* fields) is more of a resource-level thing than affected by any attributes. Those cty values are fetched early on when an RPC is received and just need to be appropriately propagated through the internal logic to where they get surfaced to provider developers.

In my quick initial investigation, I was able to find one place where the cty values were not being copied as expected: https://github.com/hashicorp/terraform-plugin-sdk/pull/1024 -- can you see if that branch helps resolve your issue?

[bflad]

Hey @gdavison 👋 Is there any improvement with using v2.21.0? If not, we'll need to figure out other potential places where the data is not being appropriately copied.

[bflad]

Closing due to lack of response. Please reach out if this is still an issue.

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