> For the complete documentation index, see [llms.txt](https://help.santesuite.org/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://help.santesuite.org/developers/applets/recipes/generating-id-on-registration.md).
# Generating ID on Registration
SanteMPI can generate a unique identifier in any format you choose whenever a patient is registered. This generation can occur regardless of where the registration originated (FHIR, HL7v2, UI, etc.).
This generator will use the [Business Rules Engine](/developers/applets/business-rules.md) to generate a new ID each time a master record is created for the patient.
### Create a new Business Rules File
Create a new JavaScript file in the **rules/** folder of your applet / plugin for SanteMPI. The basic structure of this file should be:
```javascript
///
///
///
/**
* Elbonia MPI / SanteMPI Rules for Generating new ID
* --
*/
```
### Write Generator Function
Next, write your ID generator in JavaScript, for example, this generator will create a 10 digit random identifier from UUID, and appends a mod 97 check digit to the end:
```javascript
/**
* @summary Generates an Elbonia Health Card ID
*/
function generateElboniaId() {
// Use UUID RNG to get a random string
var source = SanteDBBre.NewGuid().replace(/[a-zA-Z\-]/ig, '').substring(0, 10);
// Pad to 10 digits
source = source.pad('0', 10);
// Convert to an array of digits
var key = "0123456789";
var seed = ("0" + source).split('')
.map(function (c) {
return key.indexOf(c);
}).reduce(function (a, v, i) {
return ((a + v) * 10) % 97;
});
// Generate check digit
seed *= 10; seed %= 97;
var checkDigit = (97 - seed + 1) % 97;
checkDigit += "";
// Return identifier
var retVal = source + checkDigit.pad('0', 2);
return retVal;
};
```
### Write Business Rule
Next, we'll write a small function which accepts a patient as a parameter and adds a new identifier if one has not already been assigned
```javascript
/**
* @summary Business rule function
*/
function appendPatientID(patient) {
// Does patient have no identifiers?
if (!patient.identifier)
patient.identifier = {};
// If operating in a server environment
if (SanteDBBre.Environment == ExecutionEnvironment.Server) {
// Append ID only an existing one doesn't exist.
if (!patient.identifier.ELB_HEALTH_ID)
patient.identifier.ELB_HEALTH_ID= { value: generateElboniaId() };
}
return patient;
}
```
### Attach Business Rules to Triggers
Finally, attach the business rule functions to the SanteDB triggers. The example below will attach the append function to the BeforeInsert trigger on PatientMaster
```javascript
// Bind the business rules
SanteDBBre.AddBusinessRule("elb.rule.id", "PatientMaster", "BeforeInsert", { "deceasedDate": "null" }, appendPatientID);
```
### Register the Identifier Generator
You can also have the UI made aware of the presence of this generator by registering an identifier generator.
```javascript
// Add identifier generators
if(SanteDB.application)
SanteDB.application.addIdentifierGenerator("ELB_HEALTH_ID", generateElboniaId());
```
---
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