Convert a field that is XML to an object

[rhscjohn-dev]

I have an old SQlite db whose tables have fields that contain XML. An example of one such field in the table: CHANNEL.
"epgMapping" varchar(50) NOT NULL

Here is an example of a row fetched by an SQlite query,

 {
  oid: 7148,
  name: 'WBTV-DT',
  epgSource: 'Schedules Direct',
  epgMaping: '<epg>\r\n' +
    '  <source>Schedules Direct</source>\r\n' +
    '  <lineup>USA-OTA-29730</lineup>\r\n' +
    '  <station>19603</station>\r\n' +
    '</epg>\r\n'
}

In Zod the initial declaration for the column: epgMapping would be
epgMapping: z.string()

I wanted to convert this XML column/field to an object before passing it onto the client. I want to use Zod's preprocess(). I decided to use the npm package: fast-xml-parser for parsing xml to an object.

Here are the the zod schemas for an individual record and for an array of records.

const channelSchema = z.object({
  oid: z.number().int(),
  name: z.string(),
  epgSource: z.string(),
  epgMaping: z.preprocess((xml) => {
    const parseResult = xmlParser.parse(xml)
    return parseResult.epg
  }, z.object({ source: z.string(), lineup: z.string(), station: z.number().int() })
  )
})
const channelsSchema = z.array(channelSchema)

Javascript code to parse an individual record and an array of records.

const { z } = require('zod')
const { XMLParser } = require('fast-xml-parser')
....
const channelObj = {
  oid: 7148,
  name: 'WBTV-DT',
  epgSource: 'Schedules Direct',
  epgMaping: '<epg>\r\n' +
    '  <source>Schedules Direct</source>\r\n' +
    '  <lineup>USA-OTA-29730</lineup>\r\n' +
    '  <station>19603</station>\r\n' +
    '</epg>\r\n'
}
...
const xmlParser = new XMLParser()
...
try {
  const zodChannelObj = channelSchema.parse(channelObj)
  console.info("zodChannelObj: ", zodChannelObj)
  const zodChannelsObj = channelsSchema.parse(channelsObj)
  console.info("zodChannelsObj: ", zodChannelsObj)
} catch (error) {
  console.error(error)
}

The console. log for an individual record.

zodChannelObj:  {
  oid: 7148,
  name: 'WBTV-DT',
  epgSource: 'Schedules Direct',
  epgMaping: {
    source: 'Schedules Direct',
    lineup: 'USA-OTA-29730',
    station: 19603
  }
}