未调试时,我无法获得任何查询的结果,但是在调试
时,效果很好我还注意到,根据是否进行了调试,Realm的行为有很大不同
这只是这个想法的摘要:
我正在打印object.constructor.name
以找到对象的类型
调试时(远程使用Chrome或Safari):
let realm = new Realm(config);
realm.constructor.name --> will print (Realm)
let dogs = realm2.objects('Dog');
dogs.constructor.name --> will print (Results)
(inserting few dogs)
for (let oneDog of dogs) {
oneDog.constructor.name --> will print (RealmObject)
} --> works perfectly
但是在不进行调试时,一切都不同:
let realm = new Realm(config);
realm.constructor.name --> will print (Object)
let dogs = realm2.objects('Dog');
dogs.constructor.name --> will print nothing
(inserting few dogs)
for (let oneDog of dogs) {
oneDog.constructor.name --> not compiled
} --> will give the error below
TypeError: undefined is not a function (evaluating ‘_iterator[typeof
Symbol === “function” ? Symbol.iterator : “@@iterator”]()')
我不确定这是错误还是我的代码有问题
import React, { Component } from 'react';
import { View, Text } from 'react-native';
const Realm = require('realm');
export default class Page3Screen extends Component {
state = { messege : 'no messege' }
componentWillMount() {
const config = {
schema: [{ name: 'Dog', properties: { name: 'string' } }],
};
let realm = new Realm(config);
console.log(realm.constructor.name);
this.setState({ messege: realm.constructor.name });
realm.write(() => {
realm.create('Dog', { name: 'Zozo' });
});
let dogs = realm.objects('Dog');
// console.log(dogs.constructor.name);
// this.setState({ messege: dogs.constructor.name });
// for (let oneDog of dogs) {
// console.log(oneDog.constructor.name);
// this.setState({ messege: oneDog.constructor.name });
// }
}
render() {
return (
<View style={{ alignSelf: 'stretch', flex: 1, alignItems: 'center', justifyContent: 'center' }}>
<Text>{this.state.messege}</Text>
</View>
);
}
}
答案 0 :(得分:1)
我发现问题与this issue
有关无论出于何种原因,android上的react-native都会将旧的东西当作屎 版本的JSC,不支持语言功能 当前的React版本需要工作
updating the JSC version that ships with android解决了该问题,但我使用的是JSC版本 216113 ,而不是最新版本,以保留 minSdkVersion 17 而不是 21 < / strong>
以下是说明:
Follow steps below in order for your React Native app to use new version of JSC VM on android:
1. Add `jsc-android` to the "dependencies" section in your `package.json`:
```
dependencies {
+ "jsc-android": "^216113.0.0",
```
then run `npm install` or `yarn` (depending which npm client you use) in order for the new dependency to be installed in `node_modules`
2. Modify `andorid/build.gradle` file to add new local maven repository packaged in the `jsc-android` package to the search path:
```
allprojects {
repositories {
mavenLocal()
jcenter()
maven {
// All of React Native (JS, Obj-C sources, Android binaries) is installed from npm
url "$rootDir/../node_modules/react-native/android"
}
+ maven {
+ // Local Maven repo containing AARs with JSC library built for Android
+ url "$rootDir/../node_modules/jsc-android/android"
+ }
}
}
```
3. Update your app's `build.gradle` file located in `android/app/build.gradle` to force app builds to use new version of the JSC library as opposed to the version specified in [react-native gradle module as a dependency](https://github.com/facebook/react-native/blob/e8df8d9fd579ff14224cacdb816f9ff07eef978d/ReactAndroid/build.gradle#L289):
```
}
+configurations.all {
+ resolutionStrategy {
+ force 'org.webkit:android-jsc:r216113'
+ }
+}
dependencies {
compile fileTree(dir: "libs", include: ["*.jar"])
```
4. You're done, rebuild your app and enjoy updated version of JSC on android!
答案 1 :(得分:0)
在debugging
模式下,react-native在浏览器而不是设备中运行js代码。
由于您说它可以在浏览器上正常运行,但在设备上会损坏,因此建议您检查以下内容:
adb reverse tcp:8081 tcp:8081
$ react-native start
一些JS功能需要在React-native中使用polyfill,例如Symbol
。因此,请将以下内容添加到index.js
:
import 'core-js/es6/symbol';
import 'core-js/fn/symbol/iterator';
在非常罕见的情况下,浏览器上的JS引擎与android / ios设备之间存在差异
祝你好运。