Best Practices For Phone Number Validation In Sharepoint Columns

Why Phone Number Validation Matters

Validating phone numbers entered into SharePoint columns is an important data governance practice. Requiring phone numbers to conform to specific formats improves overall data quality and consistency within SharePoint. Normalized phone number data enables additional functionality like click-to-call from listings, search, and business applications.

Standardizing phone number storage eliminates variations like extraneous formatting characters that complicate reporting and analysis. Strict validation catches typos and malformed entries that would otherwise break features that rely on correctly structured data.

Built-in Validation Options

Regular Expressions

SharePoint’s column validation settings support specifying regular expressions to restrict values entered into a Phone Number field. Admins can apply a regex pattern requirement to constrain users to a defined phone number structure.

Leveraging regex validation ensures only properly formatted values are committed to the data store. Regex also standardizes storage by stripping unnecessary characters often entered by users. Some common regex patterns used for phone number validation:

• ^\d{10}$ – 10 digit North American numbering
• ^\d{10}(\s?\d{4})?$ – 10 digit with optional 4 digit extension
• ^(\+\d{1,2}\s)?\(?\d{3}\)?[\s.-]\d{3}[\s.-]\d{4}$ – International numbering

Data Annotation Attributes

SharePoint columns can also leverage .NET data annotation attributes to define validation rules, messages, and formatting. The Phone attribute applies a standard phone number mask during entry. Regex and range settings further constrain values.

Data annotations enable centralized validation logic that can be applied across applications and environments. Annotations also integrate with robust client-side capabilities of SharePoint Framework solutions and Power Apps.

Custom Validation Approaches

Event Receivers

When the built-in validation options are insufficient, custom event receiver code can carry out additional validation in the SharePoint data tier. Event receivers invoke C# or VB.NET logic during events like adding, updating, and deleting list items.

By handling the ItemAdding and ItemUpdating events and checking the new phone number value, event receivers can evaluate complex formatting rules. Rejecting invalid submissions prevents bad data from persisting.

Custom Field Types

For advanced phone number handling, custom SharePoint field types can encapsulate validation, rendering, and storage logic specific to phone numbers. Custom field types are defined in XML, with associated class libraries to manage logic.

In addition to server-side validation, custom field types emit client-side components for a seamless entry experience in forms. Since serialization is handled by the field type, phone numbers can be persisted in optimal formats.

Client-Side Rendering

SharePoint Framework client-side web parts open up client-side rendering and validation options for individual fields through the SharePoint REST API. Column formatting can apply patterns and restrictions directly in the browser.

Client-side validation through web parts catches bad submissions earlier in the process before a postback. Script editors can also add jQuery validation, achieving a similar effect by altering the form before submission.

Example Regex Patterns

Basic North American Number

A common regex pattern for basic 10 digit North American phone numbers (not including extensions) is:

^\d{10}$

Breaking this regex pattern down:

• ^ – Start anchor matching the beginning of the input.
• \d – Match a digit 0-9.
• {10} – Match the previous token exactly 10 times.
• $ – End anchor matching the end of the input.

With Optional Extension

To allow 4 digit extensions in addition to the base 10 digit number:

^\d{10}(\s?\d{4})?$

Explanation of components:

• ^ – Start anchor.
• \d{10} – Match 10 digits.
• (\s?\d{4}) – Optionally match a space and 4 more digits.
• ? – Marks the previous group as optional.
• $ – End anchor.

International Formats

Supporting varied international numbering requires a more flexible pattern. This one includes optional + country code, parentheses around area code, as well as hyphenated or space delimited formats:

^(\+\d{1,2}\s)?\(?\d{3}\)?[\s.-]\d{3}[\s.-]\d{4}$

Breakdown:

• ^ – Start anchor
• (\+\d{1,2}\s)? – Optionally match + plus 1-2 digit country code followed by space
• \(?\d{3}\)? – Match 3 digit area code, optionally surround by parens
• [\s.-] – Match a space, hyphen, or period delimiter
• \d{3} – Match 3 digit prefix
• [\s.-] – Delimiter
• \d{4} – Match 4 digit line number
• $ – End anchor

Best Practices

Be Specific on Allowed Formats

Document exactly which phone number formats are permitted and validate against those. Striking a balance between flexibility and strictness stabilizes data quality.

Validate on Both Server and Client

Leverage regex, custom code, and data annotations on the server to protect the database. Also implement client-side validation to catch bad data earlier and improve the user experience.

Provide User-Friendly Errors

When validation fails, display specific helpful error messages indicating exactly what needs to be corrected rather than generic failures. Guide users to enter fully valid data.

Additional Considerations

Handling Complex Use Cases

Special types of numbers like extensions, internal directories, and vanity formats may call for adjustments to validation logic. Consider these edge cases compared to requirements.

Optimizing Performance

Take care not to make regex patterns overly broad or complex since that can hamper system performance at scale. Validate only what is absolutely necessary.

Managing Legacy Data

When applying new validation, account for existing data lagging behind in quality. Provide tools to identify, report on, and remediate older entries.