Javascript react本机react本机sqlite存储未返回结果
我正在使用react原生SQLite存储中的SQLite数据库 我没有得到警报中显示的结果Javascript react本机react本机sqlite存储未返回结果,javascript,reactjs,react-native,sqlite,Javascript,Reactjs,React Native,Sqlite,我正在使用react原生SQLite存储中的SQLite数据库 我没有得到警报中显示的结果 它显示未定义的 我也尝试不使用wait和async 主文件 数据库助手 import React,{Component}来自'React'; var SQLite=require('react-native-SQLite-storage'); var dbName=“test.db”; var tableName=“tableName”; 常量DBHelper={ getWatchList:()=>{ v
它显示未定义的 我也尝试不使用wait和async 主文件 数据库助手
import React,{Component}来自'React';
var SQLite=require('react-native-SQLite-storage');
var dbName=“test.db”;
var tableName=“tableName”;
常量DBHelper={
getWatchList:()=>{
var db=SQLite.openDatabase({name:dbName,createFromLocation:1},openCB,errorCB);
数据库事务((tx)=>{
tx.executeSql(“从”+表名中选择*,
[],(发送,结果)=>{
console.log(“\n\n查询已完成\n”);
var resultItemIdArr=新数组();
for(设i=0;i{
log(“SQL错误:+err”);
}
const successCB=()=>{
log(“SQL执行良好”);
}
常量openCB=()=>{
console.log(“数据库已打开”);
}
导出默认DBHelper;
我想打印alert中的resultItemIdArr值。您在这里使用回调
db.transaction((tx)=>{
,因此您在回调中返回resultItemIdArr
。如果lib不支持承诺,您应该这样做:
getWatchList: (callback) => {
var db = SQLite.openDatabase({name : dbName, createFromLocation : 1}, openCB,errorCB);
db.transaction( (tx) => {
tx.executeSql("select * from " + tableName,
[], (tx, results) => {
console.log("\n\nQuery completed\n");
var resultItemIdArr = new Array();
for (let i = 0; i < results.rows.length; i++) {
resultItemIdArr.push(results.rows.item(i).itemId);
console.log(results.rows.item(i).itemId);
}
callback(resultItemIdArr);
});
});
},
我对react native中的sqlite有一些问题,您能帮助我吗?
import React, {Component} from 'react';
var SQLite = require('react-native-sqlite-storage');
var dbName = "test.db";
var tableName = "tableName";
const DBHelper = {
getWatchList: () => {
var db = SQLite.openDatabase({name : dbName, createFromLocation : 1}, openCB,errorCB);
db.transaction( (tx) => {
tx.executeSql("select * from " + tableName,
[], (tx, results) => {
console.log("\n\nQuery completed\n");
var resultItemIdArr = new Array();
for (let i = 0; i < results.rows.length; i++) {
resultItemIdArr.push(results.rows.item(i).itemId);
console.log(results.rows.item(i).itemId);
}
return resultItemIdArr;
});
});
},
}
const errorCB = (err) => {
console.log("SQL Error: " + err);
}
const successCB = () => {
console.log("SQL executed fine");
}
const openCB = () => {
console.log("Database OPENED");
}
export default DBHelper;
getWatchList: (callback) => {
var db = SQLite.openDatabase({name : dbName, createFromLocation : 1}, openCB,errorCB);
db.transaction( (tx) => {
tx.executeSql("select * from " + tableName,
[], (tx, results) => {
console.log("\n\nQuery completed\n");
var resultItemIdArr = new Array();
for (let i = 0; i < results.rows.length; i++) {
resultItemIdArr.push(results.rows.item(i).itemId);
console.log(results.rows.item(i).itemId);
}
callback(resultItemIdArr);
});
});
},
dbTransaction = () => {
DBHelper.getWatchList(value=>{
alert(value)
})
}