Realm 数据库的使用（iOS &Android）

技术文档参考地址https://realm.io/docs/javascript/latest/index.html

直接上步骤：

1. 打开终端运行如下命令 cd （前提是已建项目）
   2.添加依赖库 npminstall--saverealm
   3.关联依赖库 rnpmlinkrealm
   4.先看效果图（包含建表，增，删，改，查功能）

屏幕快照 2017-05-16 下午5.50.15.png

屏幕快照 2017-05-16 下午5.50.24.png

屏幕快照 2017-05-16 下午5.49.38.png

屏幕快照 2017-05-16 下午5.49.46.png

屏幕快照 2017-05-16 下午5.49.53.png

最后直接上代码：

import React, {Component} from 'react'
import {
    View,
    Text,
    StyleSheet,
    Button,
} from 'react-native'
const  Realm = require('realm');
let realm;
//1.  主键primaryKey(string|int)   表名name   内容properties
const StudentsScheam = {
    name: 'Student',
    primaryKey: 'id',
    properties: {
        id: 'int',
        s_sex: 'string',
        s_name: 'string',
        s_age: 'string',
        phone: {
            type: 'string',
            default: '15980673237'
        },//添加默认值的写法

    }
};


export default class RealmTest extends Component {


    constructor(props) {
        super(props);
        // 2.初始化 Realm
        realm = new Realm({schema: [StudentsScheam]});
        this.state = {
            s_content: (Realm.defaultPath),
            s_Length: 0,
        }
    }

    componentDidMount() {
    }


    render() {


        return (
            
                {
                        realm.write(()=>{
                            realm.create('Student',{id:1,s_age:'10',s_name:'学生1',s_sex:'男'});
                            realm.create('Student',{id:2,s_age:'11',s_name:'学生2',s_sex:'女'});
                            realm.create('Student',{id:3,s_age:'12',s_name:'学生3',s_sex:'男'});
                            realm.create('Student',{id:4,s_age:'13',s_name:'学生4',s_sex:'女'});
                            realm.create('Student',{id:5,s_age:'14',s_name:'学生5',s_sex:'男'});
                            realm.create('Student',{id:6,s_age:'15',s_name:'学生6',s_sex:'女'});
                            alert('添加数据成功！');
                        })
                    }}
                />

                {
                        let students = realm.objects('Student');
                        let student = students.filtered('id==3');
                        if (student.length > 0) {
                            realm.write(()=>{
                                realm.create('Student',{id:3,s_age:'33',s_name:'学生33'},true)
                                console.log(student[0].id+student[0].s_age+student[0].s_name+student[0].s_sex);
                                alert('id=3这条数据修改了！')
                            })

                        }else {
                            alert('该数据不存在');
                        }
                    }}
                />

                {
                        realm.write(()=>{
                            let students = realm.objects('Student');
                            let student = students.filtered('id==3');
                            if (student.length > 0){
                                realm.delete(student);
                                alert('删除成功');
                            }else {
                                alert('该数据不存在');
                            }
                        })
                    }}
                />

                {
                        realm.write(()=>{
                            let students = realm.objects('Student');
                            realm.delete(students);
                            alert('删除所有数据成功！');
                        })
                    }}
                />

                {
                        let students = realm.objects('Student');
                        let student;
                        for (var index = 1;index  0){
                                console.warn(student[0].s_name+student[0].s_age+student[0].s_sex);
                            }else {
                                alert('查询不到数据')
                            }
                        }
                    }}
                />

                {
                        let students = realm.objects('Student');
                        if (students.length > 0){
                            let student = students.filtered('id==4');
                            if (student){
                                console.warn(student[0].s_name+student[0].s_age+student[0].s_sex);

                            }
                        } else {
                            alert('未查询到id==4的数据')
                        }
                    }}
                />


            


        );
    }
}

const styles = StyleSheet.create({
    container: {
        flex: 1,
        justifyContent: 'center',
        alignItems: 'center',
        backgroundColor: '#F5FCFF',
        marginTop:20,
    },

});