Contributed EmailAddress Scalar

scalars/contributed/Juke-Duke/email-address.md

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+# EmailAddress — GraphQL Custom Scalar
+
+Author - Juke-Duke
+
+Date - 2023-02-06
+
+This is a String-based Scalar.
+
+**License and Copyright**
+
+Copyright © GraphQL contributors. This specification is licensed under
+[OWFa 1.0](https://www.openwebfoundation.org/the-agreements/the-owf-1-0-agreements-granted-claims/owfa-1-0).
+
+# Overview
+
+This Scalar represents a valid electronic mail address using a simplified version of [RFC 5322](https://www.rfc-editor.org/rfc/rfc5322).
+
+The format of an email address is `local@domain`, where the local part may consist of up to 64 UTF-8 characters, the domain part may consist of up to 63 UTF-8 characters for the domain name and 63 UTF-8 characters for the top-level domain, and the two parts are separated by an `@` sign.
+
+Other formats, including using square-bracketed IP addresses in the domain part, and quoted-string local parts, are not supported for simplicity.
+
+The local component may contain any of the following ASCII characters:
+- Uppercase and lowercase Latin letters `A` to `Z` and `a` to `z`.
+- Digits `0` to `9`.
+- Printable characters ``!#$%&'*+-/=?^_`{|}~``.
+- Dot `.`, provided that it is not the first or last character and provided also that it does not appear consecutively.
+
+The domain component may contain any of the following ASCII characters:
+- Uppercase and lowercase Latin letters `A` to `Z` and `a` to `z`.
+- Digits `0` to `9`, provided that top-level domain names are non-all-numeric (.com, .net, .org, .b2b, etc.).
+- Hyphen `-`, provided that it is not the first or last character of the domain name.
+
+**Examples**
+
+The general format is described in [RFC5322 Section 3.4.1](https://www.rfc-editor.org/rfc/rfc5322#section-3.4.1).
+These examples are taken from [WikiPedia](https://en.wikipedia.org/wiki/Email_address#Examples), which is also based off of [RFC5322 Section 3.4.1](https://www.rfc-editor.org/rfc/rfc5322#section-3.4.1).
+
+These are valid examples:
+
+| String                                           | Explanation                                                       |
+| ------------------------------------------------ | ----------------------------------------------------------------- |
+| `[email protected]`                             | An EmailAddress without any special characters.                   |
+| `[email protected]`                        | An EmailAddress with a dot inside the local part.                 |
+| `[email protected]` | An EmailAddress with dots and a plus sign inside the local part.  |
+| `[email protected]`            | An EmailAddress with a dot and hyphens inside the local part.     |
+| `[email protected]`             | An EmailAddress with hyphens inside the local part.               |
+| `[email protected]`              | An EmailAddress with a dot and plus signs inside the local part   |
+| `[email protected]`                                  | An EmailAddress with a single character in the local part.        |
+| `[email protected]`             | An EmailAddress with a hyphen in both the local and domain parts. |
+| `test/[email protected]`                             | An EmailAddress with a slash in the local part.                   |
+| `[email protected]`                              | An EmailAddress with a dot in the domain part.                    |
+| `[email protected]`                  | An EmailAddress with a bang in the local part.                    |
+| `user%[email protected]`                   | An EmailAddress with a percent sign in the local part.            |
+| `[email protected]`                              | An EmailAddress with a hyphen in the local part.                  |
+| `[email protected]`         | An EmailAddress with a non-all-numerical top-level domain.        |
+
+These are invalid examples:
+| String                                                                           | Explanation                                                       |
+| -------------------------------------------------------------------------------- | ----------------------------------------------------------------- |
+| `Abc.example.com`                                                                | No `@` sign separating the local and domain components.           |
+| `A@b@[email protected]`                                                              | Only one is allowed to divide the local and domain components.    |
+| `a"b(c)d,e:f;g<h>i[j\k][email protected]`                                            | The local part contains invalid characters.                       |
+| `just"not"[email protected]`                                                     | Quotes are not allowed in the local component.                    |
+| `this is"not\[email protected]`                                                | Spaces and backslashes are not allowed in the local component.    |
+| `this\ still\"not\\[email protected]`                                          | Spaces and backslashes are not allowed in the local component.    |
+| `1234567890123456789012345678901234567890123456789012345678901234+x@example.com` | The local component is longer than 64 characters.                 |
+| `i_like_underscore@but_its_not_allowed_in_this_part.example.com`                 | Underscores are not allowed in the domain component.              |
+| `QA[icon]CHOCOLATE[icon]@test.com`                                               | Non UTF-8 characters are not allowed in the local component.      |
+| `[email protected]`                                            | Top-level domains cannot be all numerical.                        |
+| `admin@mailserver1`                                                              | The top-level domain component is missing.                        |
+| `[email protected]`                                                 | The domain component can not have hyphes in the beginning or end. |
+
+This regex provided below follows the above examples:
+```regex
+^(?!\.)(?!.*\.\.)[a-zA-Z0-9!#$%&'*+-/=?^_`{|}~\.]{0,63}[^.]@(?!\-)[a-zA-Z0-9-]{0,62}[^-]\.(?![0-9]*$)[a-zA-Z0-9]{2,63}$
+```
+
+Regex Breakdown:
+- `^` Beginning of the string.
+- `(?!\.)(?!.*\.\.)` Look aheads that assert the local component does not start and contain consecutive dots.
+- `[a-zA-Z0-9!#$%&'*+-/=?^_`{|}~\.]` Asserts the local component may contain any of these characters.
+- `{0,63}` Asserts the length of the local component is between 1 and 64 characters inclusive.
+- `[^.]` Asserts that the local component does not end with a dot.
+- `@` Asserts that the local component is followed by an `@` sign.
+- `(?!\-)(?!.*\-\-)` Look aheads that assert the domain component name does not start or contain consecutive hyphens.
+- `[a-zA-Z0-9-]` Asserts the domain component name may contain any of these characters.
+- `{0,62}` Asserts the length of the domain component name is between 1 and 63 characters inclusive.
+- `[^-]` Asserts that the domain component name does not end with a hyphen.
+- `\.` Asserts that the domain component name is followed by a dot.
+- `(?![0-9]*$)` Look ahead that asserts the top-level domain does not only contain numbers.
+- `[a-zA-Z0-9]` Asserts the top-level domain may contain any of these characters.
+- `{2,63}` Asserts the length of the top-level domain is between 2 and 63 characters inclusive.
+- `$` End of the string.
+
+# Name
+
+The recommended name is `EmailAddress`. Alternatives may be `Email`, `E-Mail`, `MailAddress`.
+
+# Result
+
+Every result must follow the valid String formats as described above.
+
+# Input
+
+Every input following the valid String formats as described above must be accepted.
+
+# References
+
+[RFC 5322](https://www.rfc-editor.org/rfc/rfc5322)
+
+[RFC 6531](https://www.rfc-editor.org/rfc/rfc6531)
+
+[Wikipedia](https://en.wikipedia.org/wiki/Email_address)