Dimension Life (DL) has 4 Read Handler: getPet、getCount、getTopPets、checkNameUnique、Info (for process information).

Let’s check them on by one and use aos to interact with DL Process.

First, Let' sent DL process id in aos (can use any process):

DL = "cO4thcoxO57AflN5hfXjce0_DydbMJclTU9kC3S75cg"

getPet

This is a query of one Pet given address (index of pet)

We can send the message in aos:

Send({ Target = DL, Action = "getPet", Data = '{"address": "0x01100"}' })

Let’s analysis the source code:

local json = require("json")
...
-- Function to execute SQL queries and return results
local function query(stmt)
  local rows = {}
  for row in stmt:nrows() do
    table.insert(rows, row)
  end
  stmt:reset()
  return rows
end
...
-- Function to get a pet by address
local function getPet(data)
  local dataJson = json.decode(data)
  local address = dataJson.address
  local stmt = DB:prepare [[
    SELECT * FROM pets WHERE address = :address;
  ]]

  if not stmt then
    error("Failed to prepare SQL statement: " .. DB:errmsg())
  end

  stmt:bind_names({ address = address })

  local rows = query(stmt)
  return rows
end
...
-- Send({ Target = ao.id, Action = "getPet", Data = '{"address": "0x01100"}' })
-- Add getPet Handler
Handlers.add(
  "getPet",
  Handlers.utils.hasMatchingTag("Action", "getPet"),
  function (msg)
    local pet = getPet(msg.Data)
    local petsJson = json.encode(pet)
    print(pet)
    Handlers.utils.reply(petsJson)(msg)
  end
)

The json module is imported to provide json.encoding function

local json = require("json")

The code that handles the query is

-- Send({ Target = ao.id, Action = "getPet", Data = '{"address": "0x01100"}' })
-- Add getPet Handler
Handlers.add(
  "getPet",
  Handlers.utils.hasMatchingTag("Action", "getPet"),
  function (msg)
    local pet = getPet(msg.Data)
    local petsJson = json.encode(pet)
    print(pet)
    Handlers.utils.reply(petsJson)(msg)
  end

About Handler

Hanler.add has three parameters：name，pattern and handler

💡 Ref：

https://cookbook_ao.arweave.dev/references/handlers.html