CODEWITHSUNDEEP
lokijs
richpicking
richpicking

Reputation: 51

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

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.

Upvotes: 3

Views: 1187

Answers (2)

Polv
Polv

Reputation: 2208

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);

Upvotes: 0

James Wilson
James Wilson

Reputation: 289

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)

Upvotes: 1

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