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Version: v7.1.0

block_height/1

Description​

block_height/1 is a predicate which unifies the given term with the current block height.

Signature​

block_height(?Height) is det

where:

  • Height represents the current chain height at the time of the query.

Examples​

Retrieve the block height of the current block​

This scenario demonstrates how to retrieve the block height of the current block.

Here's the steps of the scenario:

  • Given a block with the following header:
keyvalue
Height100
  • Given the query:
block_height(Height).
  • When the query is run
  • Then the answer we get is:
height: 100
gas_used: 2222
answer:
  has_more: false
  variables: ["Height"]
  results:
  - substitutions:
    - variable: Height
      expression: "100"

Check that the block height is greater than a certain value​

This scenario demonstrates how to check that the block height is greater than 100. This predicate is useful for governance which requires a certain block height to be reached before a certain action is taken.

Here's the steps of the scenario:

  • Given a block with the following header:
keyvalue
Height101
  • Given the query:
block_height(Height),
Height > 100.
  • When the query is run
  • Then the answer we get is:
height: 101
gas_used: 2223
answer:
  has_more: false
  variables: ["Height"]
  results:
  - substitutions:
    - variable: Height
      expression: "101"