类型错误：this.state.contracts.map 不是函数 React

Question

I have seen this before but I still am stuck. My code where I fetch the data is as follows:

 async componentDidMount(){
   try {
     const res = await 
     fetch('https://templates.accordproject.org/template-library.json');
  const data = await res.json();
  this.setState({
  contracts: data,
  });
 } catch(e) {
 console.log(e);
   }
 }

I call it here:

 {this.state.contracts.map(contract => <Contract key={contract.id} contract={contract} />)}

I can see that state is:

 contracts: 

 {
"acceptance-of-delivery@0.0.3": {
    "name": "acceptance-of-delivery",
    "description": "This clause allows the receiver of goods to inspect them for a given time period after delivery.",
    "version": "0.0.3",
    "ciceroVersion": "^0.3.0",
    "type": 1
},   /// etcv for long string of json

I get the following error:

 TypeError: this.state.contracts.map is not a function

I am fairly certain that map expects an array but this isn't one. My question is:

If this is the problem how do I make this.state.contracts an Array so that map will work?

Answer 1

map() is an array method. You can use

Object.keys(this.state.contracts).map(key=>({[key]:this.state.contracts[key]}))

This will convert the object into an array of each contract.

Or, in the above example you can try:

Object.keys(this.state.contracts).map(key=>(<Contract key={this.state.contracts[key].id} contract={this.state.contracts[key]} />))

MDN Object.keys - Detailed on Mozilla Dev.

Also, Object.values() and Object.entries() may help.