Read the REST Response Body in Chunks

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Demonstrates Rest.ReadRespChunkBd, which reads the response body one chunk at a time, appending each chunk to a BinData. A return value of 0 signals the body is complete, while -1 indicates a read failure.

local chilkat = require("chilkat")

local rest = chilkat.Rest.new()
local bTls = true
local bAutoReconnect = true
local success = rest:connect("example.com", 443, bTls, bAutoReconnect)
if not success then
    print(rest.last_error_text)
    return
end

success = rest:send_req_no_body("GET", "/api/largefile")
if not success then
    print(rest.last_error_text)
    return
end

local statusCode = rest:read_response_header()
if statusCode < 0 then
    print(rest.last_error_text)
    return
end

-- Check for the expected success status code.  If the response is not 200, the body is likely
-- error text formatted as JSON, XML, or HTML rather than the expected content.  In that case read
-- the body as text, report it, and return.
if statusCode ~= 200 then
    local sbError = chilkat.StringBuilder.new()
    success = rest:read_resp_sb(sbError)
    if not success then
        print(rest.last_error_text)
        return
    end

    print("Request failed with status code " .. statusCode)
    print(sbError:get_as_string())
    return
end

-- The status code is 200.  Read the response body in chunks, appending each chunk to the BinData.
-- Each call waits until at least the requested number of bytes is available, unless the response
-- ends first.  A return value of 0 means the final bytes were returned and the body is complete;
-- -1 indicates a read failure.
local bdBody = chilkat.BinData.new()
local chunkResult = rest:read_resp_chunk_bd(8192, bdBody)
while chunkResult > 0 do
    chunkResult = rest:read_resp_chunk_bd(8192, bdBody)
end

if chunkResult < 0 then
    print(rest.last_error_text)
    return
end

print("Received " .. bdBody.num_bytes .. " bytes.")