Class Result

💬 Chains multiple callbacks (which return Results) together (on this Result), where every previous value is forwarded to the next callback.

• if one of the callback Results fails, the chain will return it
• on success, the last callbacks Result will be returned

Example

// every validate*** returns a Result<number>:
const veryValid: Result<number> = this.validateNumber(420).chain(
  (valid) => this.validateIntegerAndRound(valid),
  (valid) => this.validateInterval(valid, {min: 69})
);

💬 Converts the value of this Result to another Result, if this Result is successful.

Returns this failed Result otherwise.

Example

// Result<number> => Result<Integer>
this.validate(420).convertTo((valid) => new Integer(valid));

💬 Indicates if this Result was successful and converts it to reveal the getValue() method.

• To use the getValue() method, which returns the actual value, you need to check if the result was successful.
• This is necessary to avoid trying to get the value from a result that failed.
• (Result.fail('message').getValue() throws an Error because there is no value!)
• For this reason, this method has a return value of something like is Result+getValue() - i.e. after checking, getValue() is "activated".

Returns

true if the Result is successful + activation of the getValue() method on the Result

Example

const result = Result.ok('test');
result.getValue();   // ❌ TS: Property 'getValue' is protected and only accessible ...
if (result.isSuccess()) {
  result.getValue(); // ✅ fine
} else {
  result.getValue(); // ❌ same
}

💬 Calls the given callback if the Result fails.

• provides the error for the callback
• can be chained with the corresponding onSuccess() method

Example

Integer.validate(42) .onFail((error) => console.error(error)) .onSuccess((value) => console.log(Yes ${value} is an integer));

💬 Calls the given callback if the Result is successful.

• provides the value for the callback
• can be chained with the corresponding onFail() method

Example

Integer.validate(42) .onSuccess((value) => console.log(Yes ${value} is an integer)); .onFail((error) => console.error(error))

💬 Combines multiple Results in a map, checks every Result and:

• success: returns a single Result with a Record of all Results' values
• failure: returns a single Result with the error of the first failed Result

Example

const book = Result.combine({
  title: Result.ok('MyBook'),
  author: Result.ok('My Self'),
})

book.getValue() // === {title: 'MyBook', author: 'My Self'}

💬 Static constructor for a failed validation *

Returns

a failed Result

💬 Static constructor for a successful validated value

Returns

a successful Result