Starts, Ends and Contains

The starts, ends, and contains constraints validate whether a text value begins with, ends with, or contains a specified substring.

These constraints provide a lightweight and portable alternative to regular expressions and are often sufficient for enforcing simple naming conventions. They apply only to text values and can be combined with the case sensitivity flag.

Type Matrix

The following table summarizes how these constraints apply to different node types.

Node Type	S	Value Type	Details
Integer
Boolean
Float
Text		Text ValueList[Text]	Constrains the text to start with, end with, or contain one of the specified values.
Date
Time
DateTime
Bytes
TimeDelta
RegEx
Value
ValueList
ValueMatrix
Section
SectionList
SectionWithTexts
NotValidated

Rules for Starts, Ends and Contains

1. Starts: The starts constraint succeeds if the text begins with the specified substring.

   [server.identifier]
   type: "text"
   starts: "id"
   

   [server]
   identifier: "id5000"  # VALID
   

2. Ends: The ends constraint succeeds if the text ends with the specified substring.

   [server.identifier]
   type: "text"
   ends: "_id"
   

   [server]
   identifier: "example_id"  # VALID
   

3. Contains: The contains constraint succeeds if the text includes the specified substring anywhere.

   The negated form not_contains ensures that the substring does not appear.

   [server.identifier]
   type: "text"
   not_contains: "example"
   

   [server]
   identifier: "one_example_id"  # ERROR: Must not contain "example"
   

4. Multiple Values (OR Semantics): If a value list is provided, the constraint is satisfied if the text matches any of the listed values.

   [server.identifier]
   type: "text"
   starts: "server_", "client_"
   

   [server]
   identifier: "server_001"
   

   Design Rationale

   OR semantics keep these constraints simple and predictable. More complex matching scenarios that require logical AND combinations or pattern grouping should instead be implemented using matches (regular expressions).

5. Case Sensitivity: By default, comparisons are case-insensitive.

   This behavior applies equally to starts, ends, and contains and can be changed using the case_sensitive flag. See The Case Sensitive Flag for details.

Example

[api.function]
type: "text"
starts: "fn"
ends: "(x)", "(x,y)"

[api]
function: "fnAdd(x,y)"  # VALID

[server]
function: "sub(x)"  # ERROR: Must start with "fn"