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Function: cascadeKvDeleteWithDoc

    March 16, 2025
    + 12

    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).

    javascript
    Copy
    // To run configure the settings for this Function, cascadeKvDeleteWithDoc, as follows:
//
// 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