JSON Validate

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4D v20.6

JSON

JSON Validate


JSON Validate ( vJson ; vSchema ) -> Function result

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	String	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	String	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	String	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:

 C_OBJECT($oResult)

 $oResult:=JSON Validate(JSON Parse(myJson;*);mySchema)

 If($oResult.success) //validation successful

    ...

 Else //validation failed

    C_LONGINT($vLNbErr)

    C_TEXT($vTerrLine)

    $vLNbErr:=$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).