Data Trigger

Data Trigger Overview

Although data contracts provide much needed constraints on the structure of the data being stored on Dash Platform, there are limits to what they can do. Certain system data contracts may require server-side validation logic to operate effectively. For example, DPNS must enforce some rules to ensure names remain DNS compatible. Dash Platform Protocol (DPP) supports this application-specific custom logic using Data Triggers.

Details

Since all application data is submitted in the form of documents, data triggers are defined in the context of documents. To provide even more granularity, they also incorporate the document transition action so separate triggers can be created for the CREATE, REPLACE, or DELETE actions.

When document state transitions are received, DPP checks if there is a trigger associated with the document transition type and action. If there is, it then executes the trigger logic.

Note: Successful execution of the trigger logic is necessary for the document to be accepted and applied to the platform state.

Example

As an example, DPP contains several data triggers for DPNS as defined in the data trigger bindings. The domain document has added constraints for creation, replacement or deletion:

Data Contract	Document	Action(s)	Trigger Description
DPNS	domain	CREATE	Enforces DNS compatibility, validates provided hashes, and restricts top-level domain (TLD) registration
—-	—-	—-	—-
DPNS	domain	REPLACE	Prevents updates to existing documents
DPNS	domain	DELETE	Prevents deletion of existing documents
DPNS	domain	TRANSFER	Prevents transfer of existing documents
DPNS	domain	PURCHASE	Prevents purchase of existing documents
DPNS	domain	UPDATE_PRICE	Prevents updating price of existing documents

DPNS Trigger Constraints

The following table details the DPNS constraints applied via data triggers. These constraints are in addition to the ones applied directly by the DPNS data contract.

Document	Action	Constraint
domain	CREATE	Full domain length <= 253 characters
domain	CREATE	normalizedLabel matches homograph-safe conversion of label (lowercase with character substitutions: o→0, l/i→1)
domain	CREATE	normalizedParentDomainName matches homograph-safe conversion of parentDomainName
domain	CREATE	ownerId validation against records identity fields is a no-op (see note below)
domain	CREATE	Only creating a top-level domain with an authorized identity
domain	CREATE	Referenced normalizedParentDomainName must be an existing parent domain
domain	CREATE	Subdomain registration for non-top-level domains prevented if the new domain’s subdomainRules.allowSubdomains is true
domain	CREATE	Subdomain registration only allowed by the parent domain owner if the parent domain’s subdomainRules.allowSubdomains is false
domain	CREATE	Referenced preorder document must exist
domain	REPLACE	Action not allowed
domain	DELETE	Action not allowed
domain	TRANSFER	Action not allowed
domain	PURCHASE	Action not allowed
domain	UPDATE_PRICE	Action not allowed

Note

The trigger for domain CREATE attempts to validate that ownerId matches records.dashUniqueIdentityId or records.dashAliasIdentityId. However, the DPNS v1 schema defines only records.identity and sets additionalProperties: false, so neither field can exist in a valid document. Both checks are therefore permanent no-ops and records.identity is not validated against ownerId at the trigger level.

Other System Contract Triggers

In addition to DPNS, the following system contracts have registered data triggers:

Dashpay

Document	Action	Trigger Description
contactRequest	CREATE	Validates contact request fields and permissions

Masternode Rewards

Document	Action	Trigger Description
rewardShare	CREATE	Rejected unconditionally (masternodes manage reward shares via internal platform operations)
rewardShare	REPLACE	Rejected unconditionally (masternodes manage reward shares via internal platform operations)
rewardShare	DELETE	Rejected unconditionally (masternodes manage reward shares via internal platform operations)

Withdrawals

Document	Action	Trigger Description
withdrawal	REPLACE	Rejected by data trigger (withdrawal documents cannot be updated)
withdrawal	DELETE	Rejected unless status is COMPLETE