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DTO Validation

The go-mod-core-contracts leverage the go-playground/validator for DTO validation as it provides common validation function and customization mechanism.

Tag usage

EdgeX verifies the struct fields by using go-playground/validator validation tags or custom validation tags, for example: 

type Device struct {
    DBTimestamp    `json:",inline"`
    Id             string                        `json:"id,omitempty" validate:"omitempty,uuid"`
    Name           string                        `json:"name" validate:"required,edgex-dto-none-empty-string,edgex-dto-rfc3986-unreserved-chars"`
    Description    string                        `json:"description,omitempty"`
    AdminState     string                        `json:"adminState" validate:"oneof='LOCKED' 'UNLOCKED'"`
    OperatingState string                        `json:"operatingState" validate:"oneof='UP' 'DOWN' 'UNKNOWN'"`
    ...
}
The device name field contains the following validation:

  • required validation tag ensures the value is not zero, empty string, or nil
  • edgex-dto-none-empty-string validation tag trims white space and ensures the value is not an empty string
  • edgex-dto-rfc3986-unreserved-chars validation tag checks the value that does not contain reserved characters

You can find more validations in the go-playground/validator and EdgeX custom validations in the go-mod-core-contracts.

Character restriction

The EdgeX uses the custom validation edgex-dto-rfc3986-unreserved-chars to prevent the user inputting the reserved characters.

This validation allows for only the following characters:

  • alphabet: a-z, A-Z
  • digital number: 0-9
  • special character: - _ ~ : ; =

EdgeX 2.3

In EdgeX 2.3 the character restriction was reduced to support the following use cases:

  • In BACNet protocol, the user might combine object type and property as the resourceName, for example, analog_input_0:present-value
  • In OPC_UA protocol, the user might use NodeId as the resourceName, for example, ns=10;s=Hello:World