Lua

Find and Update an XML Attribute Value

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Demonstrates how to find an element in XML with a specified attribute name and then update the attribute value. Lua

local chilkat = require("chilkat")

-- Let's say you have 2 XML files with identical structures as shown directly below,
-- and you wish to update the values in the 1st XML file with those in the 2nd XML file.

-- <global>
--     <phrase id="2FADisabled" value="2factor authentication disabled"/>
--     <phrase id="2FAEnabled" value="2factor authentication enabled"/>
--     <phrase id="2FAResetFailed" value="Failed to disable two factor authentication"/>
-- </global>

-- <global>
--     <phrase id="2FAResetFailed" value="Failed to reset two factor authentication"/>
--     <phrase id="2FADisabled" value="2FA authentication disabled"/>
--     <phrase id="2FAEnabled" value="2FA authentication enabled"/>
-- </global>

-- First, initialize each of the Chilkat XML objects.
-- These could be loaded from files, but we'll just create them manually for this example..

local xml1 = chilkat.Xml.new()
xml1.tag = "global"
xml1:update_attr_at("phrase", true, "id", "2FADisabled")
xml1:update_attr_at("phrase", true, "value", "2factor authentication disabled")
xml1:update_attr_at("phrase[1]", true, "id", "2FAEnabled")
xml1:update_attr_at("phrase[1]", true, "value", "2factor authentication enabled")
xml1:update_attr_at("phrase[2]", true, "id", "2FAResetFailed")
xml1:update_attr_at("phrase[2]", true, "value", "Failed to disable two factor authentication")

local xml2 = chilkat.Xml.new()
xml2.tag = "global"
xml2:update_attr_at("phrase", true, "id", "2FAResetFailed")
xml2:update_attr_at("phrase", true, "value", "Failed to reset two factor authentication")
xml2:update_attr_at("phrase[1]", true, "id", "2FADisabled")
xml2:update_attr_at("phrase[1]", true, "value", "2FA authentication disabled")
xml2:update_attr_at("phrase[2]", true, "id", "2FAEnabled")
xml2:update_attr_at("phrase[2]", true, "value", "2FA authentication enabled")

-- Iterate over attribute values in xml2 and update the same in xml1.

local phrase_id = ""
local phrase_value = ""

local sbPath = chilkat.StringBuilder.new()

local i = 0
local count_i = xml2:num_children_having_tag("phrase")
while i < count_i do
    xml2.i = i
    phrase_id = xml2:chilkat_path("phrase[i]|(id)")
    phrase_value = xml2:chilkat_path("phrase[i]|(value)")

    -- Notice how the UpdateAttrAt method's 1st argument is a Chilkat path -- which is an expression
    -- to find the location of the XML element to be updated.
    -- Here we create a path of the form "/A/tagName,attributeName,attributeValuePattern", which means
    -- find the direct descendent of xml2 having tag=tagName, with an attribute=attributeName where the attribute value
    -- matches the attributeValuePattern.  If attributeValuePattern does not contain a "*", then it must match directly.
    -- We'll build a Chilkat path such as "/A/phrase,id,2FADisabled"
    sbPath:set_string("/A/phrase,id,")
    sbPath:append(phrase_id)

    -- This assumes the corresponding element exists in xml1.
    xml1:update_attr_at(sbPath:get_as_string(), true, "value", phrase_value)

    i = i + 1
end

-- Now see how xml1 has been updated..
print(xml1:get_xml())

-- <global>
--     <phrase id="2FADisabled" value="2FA authentication disabled"/>
--     <phrase id="2FAEnabled" value="2FA authentication enabled"/>
--     <phrase id="2FAResetFailed" value="Failed to reset two factor authentication"/>
-- </global>