lokijs - is there a way to make a compound unique index in loki?

Question

Is there a way to specify a compound unique index in loki ? I tried something like:

db.addCollection('contents', {unique: ['id', 'wsID']});

but this appears to make 2 different unique indexes.. it's the combination of the two that I'd like to make unique.

Many thanks for any suggestions.

score 1 · Answer 1 · answered Dec 27 '16 at 22:42

I did something like this by making a surrogate key:

db.addCollection('contents', {unique: 'mySurrogateKey'});

When adding records to the collection, you can create a custom property and set it to be a simple concatenation:

record.mySurrogateKey = `${record.id}${record.wsID}`
collection.insert(record)

score 0 · Answer 2 · answered Aug 28 '19 at 11:50

Related: https://github.com/techfort/LokiJS/issues/450

What I really use

import SparkMD5 from "spark-md5";
import stringify from "fast-json-stable-stringify";

public getTemplateId(t: IDbTemplate) {
    const {front, back, css, js} = t;
    return SparkMD5.hash(stringify({front, back, css, js}));
}

const tHook = (t: IDbTemplate) => {
    t.key = this.getTemplateId(t);
};

this.template.on("pre-insert", tHook);
this.template.on("pre-update", tHook);

lokijs - is there a way to make a compound unique index in loki?

2 Answers2