Function: cascadeKvDeleteWithDoc

Enterprise Edition

Goal: Perform a cascade delete operation using just the Data Service (or KV).

This function cascadeKvDeleteWithDoc merely demonstrates two different Eventing solutions
- A cascade delete using just KV or the Data Service.
- A work around for the fact that the OnDelete() entry point does not supply the actual document being deleted.
Requires Eventing Storage (or metadata collection) and a "source" collection.
Needs a Binding of type Bucket Alias (as documented in the Scriptlet).
Will utilize a special doc.type === "proxy" with a prefix KEY of "proxy::" where the suffix after "proxy::" is the KEY to the actual document.
Will operate on any mutation where 1) doc.type exists and 2) doc.type !== "proxy".
When a "proxy" document is deleted the corresponding "real" document is read from KV. This allows actions such as cURL calls to be taken based on the data in the "real document.
After the real document is read it is then deleted.
This Scriptlet uses just KV unlike the similar example Cascade Delete which uses SQL++ (or N1QL).

cascadeKvDeleteWithDoc
Input Data/Mutation(s)
Output Data/Logged

// To run configure the settings for this Function, cascadeKvDeleteWithDoc, as follows:
//
// Version 7.1+
//   "Function Scope"
//     *.* (or try bulk.data if non-privileged)
// Version 7.0+
//   "Listen to Location"
//     bulk.data.source
//   "Eventing Storage"
//     rr100.eventing.metadata
//   Binding(s)
//    1. "binding type", "alias name...", "bucket.scope.collection", "Access"
//       "bucket alias", "src_col",       "bulk.data.source",        "read and write"
//
// Version 6.X
//   "Source Bucket"
//     source
//   "MetaData Bucket"
//     metadata
//   Binding(s)
//    1. "binding type", "alias name...", "bucket",     "Access"
//       "bucket alias", "src_col",       "source",     "read and write"

function OnUpdate(doc, meta) {
    // filter out any proxy:: docs, ignore all others
    if ((meta.id).startsWith("proxy::") === true) return;
    log('OnUpdate notified of insert/update to key', meta.id);
}

function OnDelete(meta, options) {
    // only process proxy:: docs, ignore all others
    if ((meta.id).startsWith("proxy::") === false) return;

    // optional filter for just type == real or apply logic to all non 'proxy' types
    // if ((meta.id).startsWith("real::") !== true) return;

    log('A. OnDelete notified of '+options.expired ? 'delete' : 'expiry'+' of proxy', meta.id);
    var real_key = (meta.id).substr(7);
    var real_doc = src_col[real_key];
    if (real_doc) {
        delete src_col[real_key];
        log('B. OnDelete removed the real doc via key',real_key);
        log('C. OnDelete do what you want curl, etc. with the real doc',real_doc)
    } else {
        log('D. OnDelete unexpected no real doc present for key', real_key);
    }
}

We want a small "proxy" doc as a placeholder that we delete instead of the "real" document

INPUT: KEY: proxy::real::1

{
    "id": "real::1",
    "type": "proxy"
}

INPUT: KEY: real::1

{
  "id": 1,
  "type": "real",
  "f1": "yes",
  "f2": 1100,
  "fn": "n"
}

Steps to run:

Deploy the function
Then add the two test documents via the UI’s doc editor.
Then delete the proxy:real::1 doc via the UI’s doc editor.
The OnDelete() function will:
- Read and store the "real" doc for processing based on the "real" doc’s internal data.
- Perform a cascade delete of the "real" doc.

2021-07-18T20:08:04.459-07:00 [INFO] "C. OnDelete do what you want curl, etc. with the real doc" {"id":1,"type":"real","f1":"yes","f2":1100,"fn":"n"}

2021-07-18T20:08:04.459-07:00 [INFO] "B. OnDelete removed the real doc via key" "real::1"

2021-07-18T20:08:04.457-07:00 [INFO] "A. OnDelete notified of expiry of proxy" "proxy::real::1"

2021-07-18T20:08:00.757-07:00 [INFO] "OnUpdate notified of insert/update to key" "real::1"