[PWA] 13. New db and object store

Posted 2020-07-07 Answer1215

Create a db:

import idb from \'idb\';

var dbPromise = idb.open(\'test-db\', 2, function (upgradeDb) {
    switch (upgradeDb.oldVersion) {
        case 0:
            // keyval store is already created at version 1
            var keyValStore = upgradeDb.createObjectStore(\'keyval\');
            keyValStore.put("world", "hello");
        case 1:
            // new version
            upgradeDb.createObjectStore(\'people\', {keyPath: \'name\'});
    }
});

The oldVersion switch between old db and new db. So here we create a new people db.

 

ReadWrite:

dbPromise.then(function (db) {
    var tx = db.transaction(\'people\', \'readwrite\');
    var peopleStore = tx.objectStore(\'people\');

    peopleStore.put({
        name: "John", // name is the key
        age: 23,
        favoriteAnimal: \'cat\'
    });
    peopleStore.put({
        name: "Joe", // name is the key
        age: 21,
        favoriteAnimal: \'cat\'
    });
    peopleStore.put({
        name: "Jie", // name is the key
        age: 22,
        favoriteAnimal: \'dog\'
    });
    peopleStore.put({
        name: "Jay", // name is the key
        age: 24,
        favoriteAnimal: \'dog\'
    });
    return tx.complete;
}).then(function () {
    console.log("People are added");
});

dbPromise.then(function (db) {
    var tx = db.transaction(\'people\');
    var peopleStore = tx.objectStore(\'people\');
    return peopleStore.getAll();
}).then(function (people) {
    console.table(people);
});

 

---

 

Group By:
TO do gourp by we need to create index:

import idb from \'idb\';

var dbPromise = idb.open(\'test-db\', 3, function (upgradeDb) {
    switch (upgradeDb.oldVersion) {
        case 0:
            // keyval store is already created at version 1
            var keyValStore = upgradeDb.createObjectStore(\'keyval\');
            keyValStore.put("world", "hello");
        case 1:
            // new version
            upgradeDb.createObjectStore(\'people\', {keyPath: \'name\'});
        case 2:
            var peopleStore = upgradeDb.transaction.objectStore(\'people\');
            peopleStore.createIndex(\'animal\', \'favoriteAnimal\');
    }
});

 

Group by animal:

dbPromise.then(function (db) {
    var tx = db.transaction(\'people\');
    var peopleStore = tx.objectStore(\'people\');
    var animalIndex = peopleStore.index(\'animal\');
    //return animalIndex.getAll(); // all the animals
    return animalIndex.getAll(\'cat\'); // only cat
}).then(function (people) {
    console.table(people);
});