## public Election::addConstraint

### Description    

```php
public Election->addConstraint ( string $constraintClass ): bool
```

Add a constraint rules as a valid class path.
    

##### **constraintClass:** *```string```*   
A valid class path. Class must extend VoteConstraint class.    


### Return value:   

*(```bool```)* True on success.



### Throws:   

* ```CondorcetPHP\Condorcet\Throwable\VoteConstraintException```

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### Related method(s)      

* [Election::getConstraints](../Election%20Class/public%20Election--getConstraints.md)    
* [Election::clearConstraints](../Election%20Class/public%20Election--clearConstraints.md)    
* [Election::testIfVoteIsValidUnderElectionConstraints](../Election%20Class/public%20Election--testIfVoteIsValidUnderElectionConstraints.md)    

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### Examples and explanation

* **[Manual - Vote Constraints](https://github.com/julien-boudry/Condorcet/wiki/II-%23-C.-Result-%23-5.-Vote-Constraints)**