"Sweet syntax" for assigning object property if the value is true

Question

"Sweet syntax" for assigning object property if the value is true

In the project I'm working on, I find myself dealing with a lot of parsing and validating tasks. This often results in 5-10+ lines of code like if(value) object.value = value.

I considered using

object.value = value || (your favorite falsy value)

approach, but then the property ends up with a falsy value.

Here's an example (not actual production code):

let filter = {}

let thing = ctx.query.thing

thing = Validation.validateThingy(thing)

if(thing) filter.thing = thing

// +50 more parameter parsing/request body parsing

return DB.find(filter).then(etc...)

Is there a more elegant solution to handle this situation without resorting to || or iterating over the object's properties to filter out falsy values?

javascript ecmascript-6

Answer 1

Answer №1

If you want to set a value using a function, you can pass an object along with the key and value parameters.

function assignValue(object, key, value) {
    if (value) {
        object[key] = value;
    }
}

// example of how to use the function
let data = {};

assignValue(data, 'property', Validation.validateField(ctx.query.property));

Alternatively, you have the option to include the validation process inside the function itself.

function assignValue(object, key) {
    var value = Validation.validateField(ctx.query[key]);
    if (value) {
        object[key] = value;
    }
}

// example of how to use this updated function
let data = {};

assignValue(data, 'property');

Answer 2

If you want to set a value using a function, you can pass an object along with the key and value parameters.

function assignValue(object, key, value) {
    if (value) {
        object[key] = value;
    }
}

// example of how to use the function
let data = {};

assignValue(data, 'property', Validation.validateField(ctx.query.property));

Alternatively, you have the option to include the validation process inside the function itself.

function assignValue(object, key) {
    var value = Validation.validateField(ctx.query[key]);
    if (value) {
        object[key] = value;
    }
}

// example of how to use this updated function
let data = {};

assignValue(data, 'property');

Answer 3

Answer №2

One potential approach is to take advantage of short circuit evaluation with && and use

thing && (filter.thing = thing)

, but in my opinion, it would make the code harder to read. Personally, I believe sticking with your original implementation or creating a separate function would be more effective choices.

Answer 4

One potential approach is to take advantage of short circuit evaluation with && and use

thing && (filter.thing = thing)

, but in my opinion, it would make the code harder to read. Personally, I believe sticking with your original implementation or creating a separate function would be more effective choices.

Answer 5

Answer №3

What if we try this:

   item && (filter.item = item);

Answer 6

What if we try this:

   item && (filter.item = item);

Answer 7

Answer №4

Oops, my mistake, the original poster clearly mentioned:

...without using an || operator or iterating over the object's properties to filter out the false values?

...I must have overlooked that. The following code accomplishes exactly that.

For those reading this in the future without knowing the OP's preference:

You can gather the values in an object and then utilize a utility function to iterate through those values and only copy the truthy ones:

let values = {};
values.thing = Validation.validateThingy(ctx.query.thing);
// +50 others...
let filteredValues = copyTruthy({}, values);
return DB.find(filteredValues).then(/*etc...*/);

where copyTruthy is defined as:

function copyTruthy(destination, source) {
    for (const key of Object.keys(source)) {
        if (source[key]) {
            destination[key] = source[key];
        }
    }
    return destination;
}

Answer 8

Oops, my mistake, the original poster clearly mentioned:

...without using an || operator or iterating over the object's properties to filter out the false values?

...I must have overlooked that. The following code accomplishes exactly that.

For those reading this in the future without knowing the OP's preference:

You can gather the values in an object and then utilize a utility function to iterate through those values and only copy the truthy ones:

let values = {};
values.thing = Validation.validateThingy(ctx.query.thing);
// +50 others...
let filteredValues = copyTruthy({}, values);
return DB.find(filteredValues).then(/*etc...*/);

where copyTruthy is defined as:

function copyTruthy(destination, source) {
    for (const key of Object.keys(source)) {
        if (source[key]) {
            destination[key] = source[key];
        }
    }
    return destination;
}

Answer 9

Answer №5

A ternary expression can be used as a standalone statement and will function properly.

If value is true, set object.value to that value; otherwise, set it to null:

Answer 10

A ternary expression can be used as a standalone statement and will function properly.

If value is true, set object.value to that value; otherwise, set it to null:

"Sweet syntax" for assigning object property if the value is true

Answer №1

Answer №2

Answer №3

Answer №4

Answer №5

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