When would you use custom objectId in your projects?

jayson · January 24, 2022, 7:23am

Just out of curiosity, when would you guys use the custom objectId feature in your projects?

What would be the best use of the feature?

thanks,

cbaker6 · January 24, 2022, 3:10pm

IMO, custom objectId’s are useful in a few scenarios (I’m sure there are others):

If you have a local database that creates the uuid already and you are using a Parse Server as your cloud sync
If your client app can create and distribute data offline and use Parse to sync when it’s online
You data comes from a separate database that you sync with cloud

In the above cases, you can also just keep separate fields for objectId and uuid (other database identifier), but some people prefer to minimize fields. If data transmission doesn’t happen offline or the Parse Server is the only place that syncs your data, I don’t think you need to use custom objectId, but that’s just my opinion…

It’s easy to do replace objectId when a custom value in the Swift SDK. If you are interested you can look how I do it in one my of my projects.

Just take over the encoding of your ParseObjects by declaring the method below in your object:

github.com

netreconlab/ParseCareKit/blob/b39debcfc8df90f213b83664099526e61e7215b9/Sources/ParseCareKit/Objects/PCKPatient.swift#L96-L103

    
      
          public func encode(to encoder: Encoder) throws {
              var container = encoder.container(keyedBy: CodingKeys.self)
              try container.encodeIfPresent(allergies, forKey: .allergies)
              try container.encodeIfPresent(birthday, forKey: .birthday)
              try container.encodeIfPresent(name, forKey: .name)
              try container.encodeIfPresent(sex, forKey: .sex)
              try encodeVersionable(to: encoder)
          }

encodeVersionable eventually calls encodeObjectable. When encoding for parse use replace objectId with uuid and vice-versa locally. I do this in 2-steps, when I decode a local CareKit object that has it’s own uuid, I use it to replace the objectId of a ParseObject:

github.com

netreconlab/ParseCareKit/blob/b39debcfc8df90f213b83664099526e61e7215b9/Sources/ParseCareKit/Objects/PCKPatient.swift#L269-L277

    
      
          public static func copyCareKit(_ patientAny: OCKAnyPatient) throws -> PCKPatient {
          
          
    guard let patient = patientAny as? OCKPatient else {
                  throw ParseCareKitError.cantCastToNeededClassType
              }
          
          
    let encoded = try PCKUtility.jsonEncoder().encode(patient)
              var decoded = try PCKUtility.decoder().decode(PCKPatient.self, from: encoded)
              decoded.objectId = patient.uuid.uuidString

github.com

netreconlab/ParseCareKit/blob/b39debcfc8df90f213b83664099526e61e7215b9/Sources/ParseCareKit/Protocols/PCKObjectable.swift#L80-L88

    
      
          // MARK: Defaults
          extension PCKObjectable {
              public var uuid: UUID? {
                  guard let objectId = objectId,
                      let uuid = UUID(uuidString: objectId) else {
                      return nil
                  }
                  return uuid
              }

So encodeObjectable looks like:

github.com

netreconlab/ParseCareKit/blob/b39debcfc8df90f213b83664099526e61e7215b9/Sources/ParseCareKit/Protocols/PCKObjectable.swift#L206-L226

    
      
          /**
           Encodes the PCKObjectable properties of the object
           - Parameters:
              - to: the encoder the properties should be encoded to.
          */
          public func encodeObjectable(to encoder: Encoder) throws {
              var container = encoder.container(keyedBy: PCKCodingKeys.self)
          
          
    if encodingForParse {
                  if !(self is PCKOutcome) {
                      try container.encodeIfPresent(entityId, forKey: .entityId)
                  }
                  try container.encodeIfPresent(objectId, forKey: .objectId)
                  try container.encodeIfPresent(ACL, forKey: .ACL)
                  try container.encodeIfPresent(logicalClock, forKey: .logicalClock)
              } else {
                  if !(self is PCKOutcome) {
                      try container.encodeIfPresent(entityId, forKey: .id)
                  }
                  try container.encodeIfPresent(uuid, forKey: .uuid)
              }

You may need to setup code to access the Swift SDK encoders/decoders. That’s simple as well as you can just leverage that static methods of one of your ParseObject's:

github.com

netreconlab/ParseCareKit/blob/b39debcfc8df90f213b83664099526e61e7215b9/Sources/ParseCareKit/PCKUtility.swift#L89-L102

    
      
          /// Get the current Parse Encoder with custom date strategy.
          public class func encoder() -> ParseEncoder {
              PCKOutcome.getEncoder()
          }
          
          
/// Get the current JSON Encoder with custom date strategy.
          public class func jsonEncoder() -> JSONEncoder {
              PCKOutcome.getJSONEncoder()
          }
          
          
/// Get the current JSON Decoder with custom date strategy.
          public class func decoder() -> JSONDecoder {
              PCKOutcome.getDecoder()
          }

jayson · January 25, 2022, 6:07am

thank you for this detailed reply. It’s a lot for me to go through but I am. I didn’t think about the offline part of it which makes a lot of sense now that you mention it. I’m looking into how you set up PCK as well. Learning quite a bit from you.

thanks again.