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Guide

Constants

Constants are the simplest structure that we find inside the TypedApi. Constants are hard-coded key-value pairs that are embedded in the runtime metadata. In PAPI their structure is just a simple function that return its decoded value, with two alternatives. As explained in the previous section for getCompatibility Level, we have two options to get the value:

  • Promise-based call, without passing the compatibility token
  • Synchronous return, passing the compatibility token previously awaited for

This is because, like every other chain interaction, constants are also ran through the compatibility check in case any type has changed.

Let's use typedApi.constants.System.Version. See in this example how it's used:

// in this case the function is asynchronous
const versionAsync = await typedApi.constants.System.Version()
 
const compatibilityToken = await typedApi.compatibilityToken // we already learnt about it!
// in this case it's sync
const versionSync = typedApi.constants.System.Version(compatibilityToken)