I'm working on a small project at work and we have an Express.js based node application running that sends a json response that has keys in snake_case format. We have another node application that consumes this service but the response object keys are accessed in camelCase format here. I'd like to know what happens in the background to make this work.

This is the code in the REST API

app.get('/api/customer/:id', (req, res) => {
    const data = {
        "arr": [{
             "my_key": "609968029"
        }]
    }
    res.send(data);
});

This is how it is consumed in the other node application

getData = (id) => {
  const options = {
    url: `api/customer/${id}`
  };

  return httpClient.get(options)
    .then(data => {
      const arr = data.arr.map(arrEntry => {
        return {
          myKey: arrEntry.myKey
        };
      });

      return {
        arr
      };
    });
};

Here myKey correctly has the data from the REST API but I'm not sure how my_key is converted to myKey for it work.

I'm working on a small project at work and we have an Express.js based node application running that sends a json response that has keys in snake_case format. We have another node application that consumes this service but the response object keys are accessed in camelCase format here. I'd like to know what happens in the background to make this work.

This is the code in the REST API

app.get('/api/customer/:id', (req, res) => {
    const data = {
        "arr": [{
             "my_key": "609968029"
        }]
    }
    res.send(data);
});

This is how it is consumed in the other node application

getData = (id) => {
  const options = {
    url: `api/customer/${id}`
  };

  return httpClient.get(options)
    .then(data => {
      const arr = data.arr.map(arrEntry => {
        return {
          myKey: arrEntry.myKey
        };
      });

      return {
        arr
      };
    });
};

Here myKey correctly has the data from the REST API but I'm not sure how my_key is converted to myKey for it work.

• javascript
• node.js
• express

Share Improve this question Follow asked Sep 18, 2017 at 8:02 Dinesh PandiyanDinesh Pandiyan 6,31933 gold badges3535 silver badges5050 bronze badges 2

• Are there any middleware(s) installed on either end to do processing on the data? What does the data look like on the wire? What Content-Type is it sent with? – T.J. Crowder Commented Sep 18, 2017 at 8:14
• What is httpClient? – robertklep Commented Sep 18, 2017 at 8:15

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2 Answers 2

Sorted by: Reset to default 5

Turns out we have used humps library to resolve the response object from keys snake-case to camelCase.

I found this code in the lib call

const humps = require('humps');
...
axios(optionsObj)
  .then(response => {
    resolve(humps.camelizeKeys(response.data));
  })
  .catch(err => {
    reject(err);
  });

lodash can do this

_.camelCase('Foo Bar');
// => 'fooBar'