sampledb/src/SampleDB.idb.js

Sample data in a database style format.

export default dbName => new manager(dbName);

class manager {

    constructor(dbName) {
        this.dbName = dbName;
    }

    reset (
        json, 
        keysToInclude,
        deleteIfKeyNotFound = false
    ) {

        this.doReset = true;
        this.json = json;
        this.deleteIfKeyNotFound = deleteIfKeyNotFound;
        this.fullReset = !keysToInclude && deleteIfKeyNotFound;
        this.keysToInclude = keysToInclude;
        return this;

    }

    async connect () {

        if (this.doReset) 
            await this._reset();

        let version = await getDbVersion(this.dbName);
        version = this.fullReset ? 2 
            : this.doReset ? version + 1
            : version;

        let dbOpenRequest = indexedDB.open(this.dbName, version);

        return await new Promise((res,rej) => {
            dbOpenRequest.onsuccess = event => res(event.target.result);
            dbOpenRequest.onerror = () => rej(`error opening ${this.dbName}`)
            dbOpenRequest.onupgradeneeded = event => this.upgrade(event.target.result);
        });

    }

    async _reset () {
    
        if (this.json.endsWith('.json')) {
            this.json = await fetch(this.json);
            this.json = await this.json.json();
        }
    
        if (typeof this.json === 'string')
            this.json = JSON.parse(json);

        // trim irrelevant keys from source
        if (this.keysToInclude) {

            this.keysToInclude = this.keysToInclude
                .split(',')
                .map(k => k.trim());

            for(let jkey of Object.keys(this.json)) 
                if (!this.keysToInclude.includes(jkey))
                    delete this.json[jkey];

        }
        
        // Reset the entire database if parameters imply full reset
        if (this.fullReset)
            new Promise((res,rej) => {
                let request = indexedDB.deleteDatabase(this.dbName);
                request.onsuccess = event => {
                    console.log(`deleting database ${this.dbName}`);
                    res(event.target.result);
                }
                request.onerror = () => 
                    rej(`error deleteing ${this.dbName}`);
            });

        
    }    

    async upgrade (db) { 
    
        let targetKeys = [...db.objectStoreNames];
        let sourceKeys = Object.keys(this.json);
        let droppedStores = [];
        let createdStores = [];
    
        // delete irrelevant stores from target
        if (this.deleteIfKeyNotFound) {
    
            let keysToDelete = targetKeys
                .filter(tk => !sourceKeys.includes(tk));
    
            for (let key of keysToDelete) 
                await db.deleteObjectStore(key);
    
            droppedStores.push(...keysToDelete);
    
        }
    
        // add relevant stores to target
        for (let sourceKey of sourceKeys) { 
    
            if (targetKeys.includes(sourceKey)) {
                await db.deleteObjectStore(sourceKey);
                deletedStores.push(sourceKey);
            }
    
            // This gets the first key of the first row
            // (order of non-numeric keys is by insertion).
            // This is if you want to return to defaulting 
            // to first column as the primary key.  But 
            // for now I believe an out-of-line autogenerated
            // key is the best.
            let keyPath = Object.keys(this.json[sourceKey][0])[0];

            let store = await db.createObjectStore(
                sourceKey, 
                { /*keyPath,*/ autoIncrement: true }
            );
        
            for (let row of this.json[sourceKey]) 
                store.put(row);
    
            createdStores.push(sourceKey);
    
        }
    
        // log changes
        if (droppedStores.length > 0) console.log(
            `\ndropped idb.${db.name} stores:` + 
            `${droppedStores.join(',')}.\n`
        );
        if (createdStores.length > 0) console.log(
            `\ncreated idb.${db.name} stores: ` + 
            `${createdStores.join(',')}.\n`
        );
    
    }

}

function getDbVersion(dbName) {
    return new Promise((res,rej) => {
        let dbOpenRequest = indexedDB.open(dbName);
        dbOpenRequest.onsuccess = event => {
            let db = event.target.result;
            let v = db.version;
            db.close();
            res(v);
        };
    });
}