我的父组件代码

import React from 'react';
import ComponentChild from './component-child.jsx';

export default class Hello extends React.Component {
     render() {
        return  

                    
Hello world
                    
                
;
      }
}
Hello.defaultProps = {
    jsonArray: [
            {
                id: 3,
                val: "test3"
            },
            {
                id: 4,
                val: "test4"
            }
        ]
};   

我的子组件代码

import React from 'react';

//item
export default class ComponentChildList extends React.Component {
    render() {
        return 
{this.props.jsonArrayTest.val}
;
    }
}

export default class ComponentChild extends React.Component {
    constructor(props) {
        super(props);
        this.state = {
            example: 'example',
        };
    }
    render() {
        return  

                    

                        {
                            this.props.jsonArrayTest.map(function(item){
                                return 
                            })
                        }
                    
                
;
    }
}
ComponentChild.defaultProps = {
    jsonArrayTest: [
            {
                id: 1,
                val: "test1"
            },
            {
                id: 2,
                val: "test2"
            }
        ]
};     

问题:
1, 子组件报错Cannot read property 'val' of undefined
2, 父组件如何传递props覆盖子组件的默认值