fix: improve error messages for invalid payloads in Zeebe command binding

[nelson-parente]

Problem

When a duration field in a Zeebe command binding payload contains an invalid value, the error returned is unhelpful. For example, sending "timeToLive": "PT1M" (ISO-8601 — the format Zeebe itself uses) or "timeToLive": "1minute" produced:

Zeebee binding error: Invalid duration

or

time: invalid duration "PT1M"

Neither message tells the user which field failed, what value was rejected, or what format is expected.

Root cause

metadata.Duration.UnmarshalJSON (in dapr/kit) returns a bare error from time.ParseDuration or errors.New("invalid duration") for invalid inputs. The Go JSON decoder propagates this error through json.Unmarshal with no field-level context, so callers only see the raw parse error.

Affected operations and fields:

Operation	Field
publish-message	timeToLive
activate-jobs	timeout, requestTimeout
fail-job	retryBackOff
create-instance	requestTimeout

Fix

Implemented UnmarshalJSON on each affected payload struct. Duration fields are decoded individually via a shadow struct using json.RawMessage, allowing parse errors to be wrapped with the field name and a format hint.

Before:

time: invalid duration "PT1M"

After:

invalid value for field 'timeToLive': time: invalid duration "PT1M"; expected a Go duration string (e.g. "30s", "5m", "1h30m")

Note: The accepted format is a Go time.Duration string — e.g. "30s", "5m", "1h30m". ISO-8601 duration strings (like PT1M) are not supported.

Tests

Added 14 unit tests (no live broker required) asserting that:

• Each duration field name appears in the error message
• The offending value appears in the error message
• Format guidance ("duration string") is present
• Valid Go duration strings continue to parse without error

All 80 tests pass (go test ./bindings/zeebe/...).

Fixes #4093

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📖 Documentation: dapr/docs#5220

[Copilot]

Pull request overview

This PR improves the Zeebe command binding’s user-facing error messages when JSON payload duration fields contain invalid values by adding per-payload UnmarshalJSON implementations that wrap duration parsing errors with field context, and it adds unit tests to validate the new messages.

Changes:

• Added custom UnmarshalJSON methods to Zeebe command payload structs to wrap duration parsing errors with field names and format hints.
• Added unit tests covering invalid/valid/null/numeric duration inputs for each affected payload/field.

Reviewed changes

Copilot reviewed 8 out of 8 changed files in this pull request and generated 5 comments.

Show a summary per file

File	Description
bindings/zeebe/command/publish_message.go	Adds custom unmarshal for timeToLive to wrap duration parsing errors with field context.
bindings/zeebe/command/publish_message_test.go	Adds tests asserting field-scoped duration error messages and regression coverage for numeric/null inputs.
bindings/zeebe/command/fail_job.go	Adds custom unmarshal for retryBackOff to wrap duration parsing errors with field context.
bindings/zeebe/command/fail_job_test.go	Adds tests asserting field-scoped duration error messages and regression coverage for numeric/null inputs.
bindings/zeebe/command/create_instance.go	Adds custom unmarshal for requestTimeout to wrap duration parsing errors with field context.
bindings/zeebe/command/create_instance_test.go	Adds tests asserting field-scoped duration error messages and regression coverage for numeric/null inputs.
bindings/zeebe/command/activate_jobs.go	Adds custom unmarshal for timeout and requestTimeout to wrap duration parsing errors with field context.
bindings/zeebe/command/activate_jobs_test.go	Adds tests asserting field-scoped duration error messages and regression coverage for numeric/null inputs.

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[Copilot]

Pull request overview

Copilot reviewed 8 out of 8 changed files in this pull request and generated 5 comments.