对Json数据进行2级或以上深度的Javascript过滤

Question

I am working on an API in Express that filters a JSON file which contains events using the query string sent by the route.

My JSON file has the below structure

{ "events": [
   {
     "venue": {
          "name": "Name of Venue",
          "address": "Address of Venue
              }
    }]
 }

I want to place the name of venue in the QueryString and filter the object, so something like this

app.get('/api/events', function(req, res){
  var response = [];
  const { venue=null } = req.query;
  console.log(req.query);


 if (venue) {
  eventdata.filter((event) => {
   if(event.venue.name === venue){
    response.push(event);
  }
 });
}

// in case no filtering has been applied, respond with all venues
  if(Object.keys(req.query).length === 0){
    response = eventdata;
  }

  res.json(response);
});

But I think because the venue name is 2 layers deep into the object it is not creating a match. I get an error

Cannot read property 'name' of undefined

If I don't put in a query string I get all the results.

If I use localhost:3000/api/events?venue=abc%20bar I get the error.

I'm guessing it is something to do with the depth of the "name" key/value pair in the JSON but I'm not sure. ie line

if(event.venue.name === venue)

Any ideas? Thanks

Answer 1

U can do something like this:

  **if(event.venue && event.venue.name) {

    }**

You can do a nested check so that you do not encounter the error( cannot read name of undefined)

Answer 2

That's not how filter works. The function inside should return a boolean which indicates whether the element should be kept.

So something like

var response = eventdata.filter((evt) => {
    return evt.venue && evt.venue.name && evt.venue.name == venue;
});