[Ramda] Handle Errors in Ramda Pipelines with tryCatch

Handling your logic with composable functions makes your code declarative, leading to code that's easy to read and easy to test. Breaking that up to wrap some risky function in a try/catch block introduces imperative code and makes it harder to maintain that declarative approach. With Ramda's tryCatch function, you can handle errors right in the middle of a composition and leave your code clean and functional. We'll also see how you can use propOr to avoid common "cannot find X of undefined" errors.

 

const R = require('ramda');

const person = {
    id: 1,
    name: 'Joe'
};

/*
* The problem for this code:
* R.prop('name') assume that the object passed in has 'name' prop
* But what if the object is undefined? Then we will get error.
*
* Solution: R.tryCatch()
* */
/*
const getPersonName = R.prop('name');
const getUpperCaseName = R.pipe(
    getPersonName,
    R.toUpper
);
const res = getUpperCaseName(person); // ERROR
*/

const getPersonName = R.tryCatch(R.prop('name'), R.always('Default'));
const getUpperCaseName = R.pipe(
    getPersonName,
    R.toUpper
);
const res = getUpperCaseName(undefined);  // DEFAULT


console.log(res);

 

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