JSON Validate
JSON Validate ( vJson ; vSchema ) : Object
| Parameter | Type | Description | |
|---|---|---|---|
| vJson | Object | → | JSON object to validate |
| vSchema | Object | → | JSON schema used to validate JSON objects |
| Function result | Object | ← | Validation status and errors (if any) |
Description
The JSON Validate command checks the compliance of the vJson JSON contents with the rules defined in the vSchema JSON schema. If the JSON is invalid, the command returns a detailed description of error(s).
In vJson, pass a JSON object containing the JSON contents to be validated.
Note: Validating a JSON string consists of checking that it follows the rules defined in a JSON schema. This is different from checking that the JSON is well-formed, which is done by the JSON Parse command.
In vSchema, pass the JSON schema to use for the validation. For more information on how to create a JSON schema, you may consult the json-schema.org web site.
Note: To validate a JSON object, 4D uses the norm described in the JSON Schema Validation document (this draft is still being written and can evolve in the future). 4D's current implementation is based upon the version 4 of the draft.
If the JSON schema is not valid, 4D returns a Null object and throws an error that can be caught by an on error call method.
The JSON Validate returns an object that provides the status of the validation. This object can contain the following properties:
| Property name | Type | Description |
|---|---|---|
| success | Boolean | True if vJson is validated, false otherwise. If false, the errors property is also returned |
| errors | Object collection | List of error objects if the vJson is not validated (see below) |
Each error object of the errors collection contains the following properties:
| Property name | Type | Description |
|---|---|---|
| code | Number | Error code |
| jsonPath | Text | JSON path that cannot be validated in vJson |
| line | Number | Line number of the error in the JSON file. This property is filled if the JSON has been parsed by JSON Parse with the * parameter. Otherwise, the property is omitted. |
| message | Text | Error message |
| offset | Number | Line offset of the error in the JSON file. This property is filled if the JSON has been parsed by JSON Parse with the * parameter. Otherwise, the property is omitted. |
| schemaPaths | Text | JSON path in the schema that causes the validation error |
Error management
The following errors may be returned :
| Code | JSON Keyword | Message |
|---|---|---|
| 2 | multipleOf | Error while validating against 'multipleOf' key. |
| 3 | maximum | The value provided should not be greater than specified in the schema ("{s1}"). |
| 4 | exclusiveMaximum | The value provided should be less than specified in the schema ("{s1}"). |
| 5 | minimum | The value provided should not be less than specified in the schema ("{s1}"). |
| 6 | exclusiveMinimum | The value provided should be greater than specified in the schema ("{s1}"). |
| 7 | maxLength | The string is longer than specified in the schema. |
| 8 | minLength | The string is shorter than specified in the schema. |
| 9 | pattern | The string "{s1}" does not match the pattern in the schema:{s2}. |
| 10 | additionalItems | Error while validating an array. JSON contains more elements than specified in the schema. |
| 11 | maxItems | The array contains more items than specified in the schema. |
| 12 | minItems | The array contains less items than specified in the schema. |
| 13 | uniqueItems | Error while validating an array. Elements are not unique. Another instance of "{s1}" is already in the array. |
| 14 | maxProperties | The number of properties is greater than specified in the schema. |
| 15 | minProperties | The number of properties is less than specified in the schema. |
| 16 | required | The required property "{s1}" is missing. |
| 17 | additionalProperties | No additional properties allowed by the schema. The property(ies) {s1} should be removed. |
| 18 | dependencies | The property "{s1}" requires the property "{s2}". |
| 19 | enum | Error while validating against 'enum' key. "{s1}" does not match any enum element in the schema. |
| 20 | type | Incorrect type. Expected type is: {s1} |
| 21 | oneOf | The JSON matches more than one value. |
| 22 | oneOf | The JSON does not match any value. |
| 23 | not | The JSON is valid against the value of 'not'. |
| 24 | format | The string does not match ("{s1}") |
Example
You want to validate a JSON object with a schema and get the list of validation errors, if any, and store error lines and messages in a text variable:
var $oResult : Object
$oResult:=JSON Validate(JSON Parse(myJson;*);mySchema)
If($oResult.success) //validation successful
...
Else //validation failed
var $vLNbErr : Integer
var $vTerrLine : Text
$vLNbErr:=$oResult.errors.length ///get the number of error(s)
ALERT(String($vLNbErr)+" validation error(s) found.")
For($i;0;$vLNbErr)
$vTerrLine:=$vTerrLine+$oResult.errors[$i].message+" "+String($oResult.errors[$i].line)+Carriage return
End for
End if
Note: This example requires that object notation is activated (see the Compatibility page).