Create a meta-data document

Orders in CoW Protocol can contain arbitrary data in a field called AppData.

The SDK facilitates the creation of these documents, and getting the AppData Hex number that summarizes it.

The most important thing to define in the meta-data is the name of your app, so the order-flow can be credited to it.

import { MetadataApi } from '@cowprotocol/app-data'

export const metadataApi = new MetadataApi()

const appCode = 'YOUR_APP_CODE'

const appDataDoc = await metadataApi.generateAppDataDoc({
    appDataParams: { appCode },
})

console.log(appDataDoc)

This will create a document similar to:

{
  "version": "0.5.0",
  "appCode": "YOUR_APP_CODE",
  "metadata": {}
} 

After creating the most basic document, you can see how to attach additional meta-data items.

For example, you could give information about who reffered the user creating the order.

import { MetadataApi } from '@cowprotocol/app-data'

export const metadataApi = new MetadataApi()

const appCode = 'YOUR_APP_CODE'
const referrerParams = { address: '0x1f5B740436Fc5935622e92aa3b46818906F416E9' }

const appDataDoc = await metadataApi.generateAppDataDoc({
    appDataParams: { appCode },
    metadataParams: { referrerParams },
})

console.log(appDataDoc)

This will create a document similar to:

{
    "version": "0.5.0",
    "appCode": "YOUR_APP_CODE",
    "metadata": {
      "referrer": {
        "address": "0x1f5B740436Fc5935622e92aa3b46818906F416E9",
        "version": "0.2.0"
      },
    },
}

For a complete list of meta-data that can be attach check @cowprotocol/app-data

Know that you know how to create meta-data documents, let's review how to get the appData that we need when we post orders. Just a hint, this appData is deterministic based on the content of the meta-data document.