# Validating FHIR Resources with `$validate`
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AWS HealthLake now supports the `$validate` operation for FHIR resources, enabling you to validate a resource against the FHIR specification and check its conformance to a specified profile or base resource definition without performing any storage operations. This operation is particularly useful when you need to:
+ Validate FHIR CMS compliance requirements
+ Test resources prior to using them in production
+ Provide real-time validation feedback as users edit clinical data
+ Reduce invalid data submissions to create and update APIs

## Usage


The `$validate` operation can be invoked on FHIR resources using POST methods:

**Supported Operations**  


```
POST [base]/[type]/[id]/$validate
POST [base]/[type]/$validate
```

## Supported Payloads


**Parameters resource**  


HealthLake supports the following FHIR `$validate` parameters:


| Parameter | Type | Required | Description | 
| --- | --- | --- | --- | 
| resource | Resource | Yes | The resource to be validated | 
| profile | canonical | No | Canonical URL of the profile to validate against | 
| mode | code | No | Validation mode: create, or update | 

**Direct resource with Query Parameters**  



| Parameter | Type | Required | Description | 
| --- | --- | --- | --- | 
| profile | canonical | No | Canonical URL of the profile to validate against | 
| mode | code | No | Validation mode: create, or update | 

## Examples


**POST Request for Resource with ID and Parameters payload**  


```
POST [base]/Patient/example-patient/$validate
Content-Type: application/fhir+json

{
  "resourceType": "Parameters",
  "parameter": [
    {
      "name": "resource",
      "resource": {
        "resourceType": "Patient",
        "id": "example-patient",
        "name": [
          {
            "family": "Smith",
            "given": ["John"]
          }
        ],
        "gender": "male",
        "birthDate": "1990-01-01"
      }
    },
    {
      "name": "profile",
      "valueCanonical": "http://hl7.org/fhir/us/core/StructureDefinition/us-core-patient"
    },
    {
      "name": "mode",
      "valueString": "create"
    }
  ]
}
```

**POST Request for Resource Type and Parameters payload**  


```
POST [base]/Patient/$validate
Content-Type: application/fhir+json

{
  "resourceType": "Parameters",
  "parameter": [
    {
      "name": "resource",
      "resource": {
        "resourceType": "Patient",
        "name": [
          {
            "family": "Doe",
            "given": ["Jane"]
          }
        ],
        "gender": "female",
        "birthDate": "1985-05-15"
      }
    },
    {
      "name": "profile",
      "valueCanonical": "http://hl7.org/fhir/us/core/StructureDefinition/us-core-patient"
    },
    {
      "name": "mode",
      "valueString": "update"
    }
  ]
}
```

**POST Request for Resource with ID and direct resource payload**  


```
POST [base]/Patient/example-patient/$validate?profile=http://hl7.org/fhir/us/core/StructureDefinition/us-core-patient&mode=create
Content-Type: application/fhir+json

{
    "resourceType": "Patient",
    "id": "example-patient",
    "name": [
        {
        "family": "Smith",
        "given": ["John"]
        }
    ],
    "gender": "male",
    "birthDate": "1990-01-01"
}
```

**POST Request for Resource Type and direct resource payload**  


```
POST [base]/Patient/$validate?profile=http://hl7.org/fhir/us/core/StructureDefinition/us-core-patient&mode=create
Content-Type: application/fhir+json

{
    "resourceType": "Patient",
    "id": "example-patient",
    "name": [
        {
        "family": "Smith",
        "given": ["John"]
        }
    ],
    "gender": "male",
    "birthDate": "1990-01-01"
}
```

**Sample Response**  
The operation returns an OperationOutcome resource with validation results:

```
{
  "resourceType": "OperationOutcome",
  "issue": [
    {
      "severity": "information",
      "code": "informational",
      "diagnostics": "Validation successful"
    }
  ]
}
```

**Sample Response with Validation Errors**  


```
{
  "resourceType": "OperationOutcome",
  "issue": [
    {
      "severity": "error",
      "code": "required",
      "details": {
        "text": "Missing required element"
      },
      "diagnostics": "Patient.identifier is required by the US Core Patient profile",
      "location": [
        "Patient.identifier"
      ]
    },
    {
      "severity": "warning",
      "code": "code-invalid",
      "details": {
        "text": "Invalid code value"
      },
      "diagnostics": "The provided gender code is not from the required value set",
      "location": [
        "Patient.gender"
      ]
    }
  ]
}
```

## Behavior


The `$validate` operation:

1. Validates the resource against the FHIR specification and base resource definition

1. Checks conformance to specified profiles when the `profile` parameter is provided

1. Validates based on the specified mode (`create` or `update`)

1. Returns detailed validation results including errors, warnings, and informational messages

1. Does not perform any storage operations - validation only

1. Returns HTTP 200 OK when validation can be performed, regardless of whether validation issues are found

## Validation Modes

+ **create**: Validates the resource as if it were being created (new resource)
+ **update**: Validates the resource as if it were being updated (existing resource)

## Error Handling


The operation returns:
+ 200 OK: Validation was performed successfully (regardless of validation outcome)
+ 400 Bad Request: Invalid request format or parameters
+ 404 Not Found: Resource type or profile not found

For more information about the `$validate` operation specification, see the [FHIR R4 Resource `$validate`](https://www.hl7.org/fhir/R4/operation-resource-validate.html) documentation.