Merge branch '3.4' into 4.1

* 3.4:
  Added a note about the usage of NotBlank

Author: javiereguiluz

reference/constraints/Bic.rst

@@ -80,6 +80,8 @@ will contain a Business Identifier Code (BIC).
             }
         }
 
+.. include:: /reference/constraints/_empty-values-are-valid.rst.inc
+
 Available Options
 -----------------
 

reference/constraints/CardScheme.rst

@@ -96,6 +96,8 @@ on an object that will contain a credit card number.
             }
         }
 
+.. include:: /reference/constraints/_empty-values-are-valid.rst.inc
+
 Available Options
 -----------------
 

reference/constraints/Country.rst

@@ -73,6 +73,8 @@ Basic Usage
             }
         }
 
+.. include:: /reference/constraints/_empty-values-are-valid.rst.inc
+
 Options
 -------
 

reference/constraints/Currency.rst

@@ -76,6 +76,8 @@ a valid currency, you could do the following:
             }
         }
 
+.. include:: /reference/constraints/_empty-values-are-valid.rst.inc
+
 Options
 -------
 

reference/constraints/Date.rst

@@ -75,6 +75,8 @@ Basic Usage
             }
         }
 
+.. include:: /reference/constraints/_empty-values-are-valid.rst.inc
+
 Options
 -------
 

reference/constraints/DateTime.rst

@@ -76,6 +76,8 @@ Basic Usage
             }
         }
 
+.. include:: /reference/constraints/_empty-values-are-valid.rst.inc
+
 Options
 -------
 

reference/constraints/Email.rst

@@ -88,6 +88,8 @@ Basic Usage
             }
         }
 
+.. include:: /reference/constraints/_empty-values-are-valid.rst.inc
+
 Options
 -------
 

reference/constraints/File.rst

@@ -150,6 +150,8 @@ The ``bioFile`` property is validated to guarantee that it is a real file.
 Its size and mime type are also validated because the appropriate options
 have been specified.
 
+.. include:: /reference/constraints/_empty-values-are-valid.rst.inc
+
 Options
 -------
 

reference/constraints/Iban.rst

@@ -90,6 +90,8 @@ will contain an International Bank Account Number.
             }
         }
 
+.. include:: /reference/constraints/_empty-values-are-valid.rst.inc
+
 Available Options
 -----------------
 

reference/constraints/Ip.rst

@@ -76,6 +76,8 @@ Basic Usage
             }
         }
 
+.. include:: /reference/constraints/_empty-values-are-valid.rst.inc
+
 Options
 -------
 

reference/constraints/Isbn.rst

@@ -94,6 +94,8 @@ on an object that will contain an ISBN.
             }
         }
 
+.. include:: /reference/constraints/_empty-values-are-valid.rst.inc
+
 Available Options
 -----------------
 

reference/constraints/Issn.rst

@@ -76,6 +76,8 @@ Basic Usage
             }
         }
 
+.. include:: /reference/constraints/_empty-values-are-valid.rst.inc
+
 Options
 -------
 

reference/constraints/Language.rst

@@ -74,6 +74,8 @@ Basic Usage
             }
         }
 
+.. include:: /reference/constraints/_empty-values-are-valid.rst.inc
+
 Options
 -------
 

reference/constraints/Length.rst

@@ -110,6 +110,8 @@ and "50", you might add the following:
             }
         }
 
+.. include:: /reference/constraints/_empty-values-are-valid.rst.inc
+
 Options
 -------
 

reference/constraints/Locale.rst

@@ -84,6 +84,8 @@ Basic Usage
             }
         }
 
+.. include:: /reference/constraints/_empty-values-are-valid.rst.inc
+
 Options
 -------
 

reference/constraints/Luhn.rst

@@ -85,6 +85,8 @@ will contain a credit card number.
             }
         }
 
+.. include:: /reference/constraints/_empty-values-are-valid.rst.inc
+
 Available Options
 -----------------
 

reference/constraints/Regex.rst

@@ -161,6 +161,8 @@ it a custom message:
             }
         }
 
+.. include:: /reference/constraints/_empty-values-are-valid.rst.inc
+
 Options
 -------
 

reference/constraints/Time.rst

@@ -78,6 +78,8 @@ of the day when the event starts:
             }
         }
 
+.. include:: /reference/constraints/_empty-values-are-valid.rst.inc
+
 Options
 -------
 

reference/constraints/Url.rst

@@ -77,6 +77,8 @@ Basic Usage
             }
         }
 
+.. include:: /reference/constraints/_empty-values-are-valid.rst.inc
+
 Options
 -------
 

reference/constraints/Uuid.rst

@@ -78,6 +78,8 @@ Basic Usage
             }
         }
 
+.. include:: /reference/constraints/_empty-values-are-valid.rst.inc
+
 Options
 -------
 

reference/constraints/_empty-values-are-valid.rst.inc

@@ -0,0 +1,7 @@
+.. note::
+
+    As with most of the other constraints, ``null`` values and empty strings
+    are considered valid values. Otherwise, in addition to validating this value,
+    you would also be requiring it, making it impossible to be optional. That's
+    why it's common to combine this constraint with
+    :doc:`NotBlank </reference/constraints/NotBlank>`.