前言
indexedDb是一种非关系型数据库，跟以往用到的数据库结构还是有蛮大差距的。结合实际的应用场景，我对indexedDb做了Promise二次封装。不多说，直接上代码。
代码
let idxDb = {
dbName: "indexedDb",
dbVersion: 20191216,
db: {},
initDb(cbk_rslt) {
let dbVersion = 20191216;
let request = window.indexedDB.open("example", dbVersion);
request.onerror = (event) => {
console.log('数据库打开报错');
cbk_rslt({
event: 'onerror'
});
};
request.onsuccess = (event) => {
this.db = event.target.result;
console.log('数据库打开成功');
cbk_rslt({
event: 'onsuccess'
});
};
request.onupgradeneeded = (event) => {
console.log('数据库打开成功2');
this.db = event.target.result;
let objectStore;
if (!this.db.objectStoreNames.contains('student')) {
objectStore = this.db.createObjectStore('student', {
keyPath: 'kjh'
});
objectStore.createIndex('name', 'name', {
unique: false
});
objectStore.createIndex('xm', 'xm', {
unique: true
});
}
cbk_rslt({
event: 'onupgradeneeded'
});
}
},
openDB() {
return new Promise((resolve, reject) => {
let request = window.indexedDB.open(this.dbName, this.dbVersion);
request.onerror = (event) => {
reject("IndexedDB数据库打开错误，" + event);
};
request.onsuccess = (event) => {
resolve(event.target.result);
};
});
},
closeDb() {
this.db.close();
},
deleteDb(dbname) {
this.db.deleteDatabase(dbname);
},
addData(table, value) {
try {
let p = this.openDB();
p.then(data => {
this.db = data;
}).catch(error => {
return console.log(error);
});
let request = this.db.transaction([table], 'readwrite')
.objectStore(table)
.add(value);
return new Promise(resolve => {
request.onsuccess = () => {
resolve({
flag: true
});
};
request.onerror = () => {
resolve({
flag: false
});
};
});
} catch (error) {
return Promise.resolve({
flag: false
});
}
},
getData(table, key) {
try {
let transaction = this.db.transaction([table], 'readonly');
let store = transaction.objectStore(table);
let request = store.get(key);
// let request = this.db.transaction([table], 'read')
// .objectStore(table)
// .get(key);
return new Promise(resolve => {
request.onsuccess = () => {
resolve({
flag: true,
result: request.result
});
};
request.onerror = () => {
resolve({
flag: false
});
};
});
} catch (error) {
return Promise.resolve({
flag: false
});
}
},
putData(table, value) {
try {
let p = this.openDB();
p.then(data => {
this.db = data;
}).catch(error => {
return console.log(error);
});
let request = this.db.transaction([table], 'readwrite')
.objectStore(table)
.put(value);
return new Promise(resolve => {
request.onsuccess = () => {
resolve({
flag: true
});
};
request.onerror = () => {
resolve({
flag: false
});
};
});
} catch (error) {
return Promise.resolve({
result: false
});
}
},
selectData(table, index, value) {
try {
let p = this.openDB();
p.then(data => {
this.db = data;
}).catch(error => {
return console.log(error);
});
let selectQuene = new Array(0);
let request = this.db.transaction([table], 'readwrite')
.objectStore(table).index(index)
.openCursor(IDBKeyRange.only(value));
return new Promise(resolve => {
request.onsuccess = (e) => {
let cursor = e.target.result;
if (cursor) {
selectQuene.push(request.result.value);
// resolve({
// flag: true,
// result: request.result
// });
// console.log(cursor);
cursor.continue();
} else {
resolve({
flag: true,
result: selectQuene
});
}
};
request.onerror = () => {
resolve({
flag: false
});
};
});
} catch (error) {
return Promise.resolve({
flag: false
});
}
},
selectDataBound(table, index, valueX, valueY) {
try {
let p = this.openDB();
p.then(data => {
this.db = data;
}).catch(error => {
return console.log(error);
});
let selectQuene = new Array(0);
let request = this.db.transaction([table], 'readwrite')
.objectStore(table).index(index)
.openCursor(IDBKeyRange.bound(valueX, valueY));
return new Promise(resolve => {
request.onsuccess = (e) => {
let cursor = e.target.result;
if (cursor) {
selectQuene.push(request.result.value);
// resolve({
// flag: true,
// result: request.result
// });
// console.log(cursor);
cursor.continue();
} else {
resolve({
flag: true,
result: selectQuene
});
}
};
request.onerror = () => {
resolve({
flag: false
});
};
});
} catch (error) {
return Promise.resolve({
flag: false
});
}
},
countData(table, index, value) {
try {
let p = this.openDB();
p.then(data => {
this.db = data;
}).catch(error => {
return console.log(error);
});
console.log(index);
let request = this.db.transaction([table], 'readonly')
.objectStore(table).count();
return new Promise(resolve => {
request.onsuccess = () => {
resolve({
flag: true,
result: request.result
});
};
request.onerror = () => {
resolve({
flag: false
});
};
});
} catch (error) {
return Promise.resolve({
result: false
});
}
},
countData2(table, index, value) {
try {
let p = this.openDB();
p.then(data => {
this.db = data;
}).catch(error => {
return console.log(error);
});
console.log(1)
let nCount = 0;
let request = this.db.transaction([table], 'readonly')
.objectStore(table).index(index)
.openCursor(IDBKeyRange.only(value));
return new Promise(resolve => {
request.onsuccess = (e) => {
let cursor = e.target.result;
if (cursor) {
nCount++;
cursor.continue();
} else {
resolve({
flag: true,
result: nCount
});
}
};
request.onerror = () => {
resolve({
flag: false
});
};
});
} catch (error) {
return Promise.resolve({
flag: false
});
}
},
cleaerObjectstore(table) {
try {
let p = this.openDB();
p.then(data => {
this.db = data;
}).catch(error => {
return console.log(error);
});
let request = this.db.transaction([table], 'readwrite')
.objectStore(table).clear();
return new Promise(resolve => {
request.onsuccess = () => {
resolve({
flag: true
});
};
request.onerror = () => {
resolve({
flag: false
});
};
});
} catch (error) {
return Promise.resolve({
result: false
});
}
}
}
export default idxDb;
分析
initDb() 和 openDB() 分别用来创建数据库和打开数据库
addData() 用来添加新的数据，等同于insert
putData() 用来修改数据，等同于update
selectData 用来选择指定数据，等同于select
selectDataBound 用来选择指定数据并添加条件筛选，等同于select+where
countData 用来统计数据
总结
对indexedDb的接口进行这样的封装后，能够基本完成常规数据库的增删改查的操作。当然如果有其他的应用也可以进一步的去实现。
