100% VFP Json Parser & Utilities
Version: 1.29
Author: V. Espina / A. Ferreira
Just add this code at the beginning of your main program:
DO json
This will create a public object called JSON that you can use to perform many JSON-related tasks. If you prefer to use local instances, then you can instantiate the class this way:
LOCAL oJSON
oJSON = CREATEOBJECT("JSON")
LOCAL oPerson
oPerson = JSON.Parse('{ "firstName": "Victor", "lastName": "Espina", "YOB": 1970 }')
IF JSON.lastError.hasError
?JSON.lastError.Message
RETURN
ENDIF
?oPerson.firstName --> "Victor"
LOCAL oPerson,cPerson
oPerson = CREATE("Empty")
ADDProperty(oPerson, "firstName", "Victor")
ADDProperty(oPerson, "lastName", "Espina")
ADDProperty(oPerson, "YOB", 1970)
cPerson = JSON.Stringify(oPerson)
?cPerson -> '{ "firstName" : "Victor", "lastName": "Espina", "YOB": 1970 }'
LOCAL ARRAY aFruits[3]
aFruits[1] = "Apple"
aFruits[2] = "Orange"
aFruits[3] = "Pear"
LOCAL cFruits
cFruits = JSON.stringify(@aFruits)
?cFruits -> '["Apple","Orange","Pear"]'
?JSON.Beautify('{ "firstName" : "Victor", "lastName": "Espina", "YOB": 1970 }')
--> {
"firstName": "Victor",
"lastName": "Espina",
"YOB: 1970
}
The library uses a singleton class to handle errors in all classes, so any error ocurred anywhere in the library can be checked using json.lastError object:
IF json.lastError.hasError && Something went wrong
?"Error #", json.lastError.errorNo
?"Message", json.lastError.Message
?"Procedure", json.lastError.Procedure
?"Line #", json.lastError.lineNo
?"Details", json.lastError.Details
ENDIF
If you need to parse a large JSON string, you can now activate a fast parser mode that will parse the JSON much more faster than using the normal VFP-based parser. To activate this mode, just add this command before the call to the Parse method:
JSON.useFastParser = .T.
By default, the result obtained from fast parsing is a JS object that is automatically converted to foxpro objects to normalize the result between normal and fast parsing, but this adds a small performance penalty to the process. To avoid this, and receive the original JS object, set:
JSON.normalizeResults = .F.
Take in consideration that JS objects does not behave the same way foxpro objects does. For example, you only can iterate on an array's elements using FOR EACH:
FOR EACH oElem IN jsonData.arrayProperty
* Here you can access element's properties
ENDFOR
JSON library can convert a data cursor into a JSON string representation, optionally including the cursor schema. If a cursor is converted to JSON string including the schema the cursor can be recreated later exactly as it was (using parseCursor). If no schema was added, then cursor can still be recreated, but the library will deduce the schema from the cursor data (using toCursor).
string = JSON.Stringify("alias" [,withSchema] [,datasession]) [8]
JSON.parseCursor(string [, "alias"] [,datasession]) [1]
JSON.toCursor(string | object, "alias" [,datasession]) [2]
Schemas allows to declare public reusable cursor structures (schemas) and create empty cursors based on those pre-declared schemas. Schemas are based on jsonSchema class, wich can be used directly also for on-the-fly dinamically cursor creation.
oSchema = JSON.Schemas.New(name) [3]
oSchema = JSON.Schemas.newFromCursor(name, "alias" [,datasession])
oSchema = JSON.Schemas.newFromString(name, string) [4]
bool = JSON.Schemas.Create(cursorName, schemaName [,datasession])
oSchema = JSON.Schemas.Get(name)
bool = JSON.Schemas.Exist(name)
bool = JSON.Schemas.Delete(name)
bool = oSchema.initWithAlias("alias" [,datasession])
bool = oSchema.initWithJSON(string) [1]
bool = oSchema.addColumn(name, type [,lon] [,dec])
bool = oSchema.addColumn(object) [5]
bool = oSchema.addColumnFromString(string) [6]
bool = oSchema.existColumn(name)
bool = oSchema.delColumn(name)
string = oSchema.toString([bool]) [7]
bool = oSchema.toCursor("alias" [,datasession])
The JSON object implements 3 methods that are useful when sending and receiving data to/from a REST-like webservice.
This method allows to request information from a webservice that returns information in either JSON or XML format. In boths cases, the method returns an object that represents the received information:
LOCAL oResp
oResp = JSON.httpGet("https://api.agify.io/?name=bella")
IF NOT oResp.hasError
?oResp.JSON.name -> "bella"
?oResp.JSON.age -> 37
ELSE
?oResp.errorMsg
ENDIF
The full syntax of httpGet() is:
resp = JSON.httpGet(cUrl [,cContentType] [,cHeaders] [,nTimeout[)
Multiple headers can be passed using CRLF to separate them.
This method allows to send information to a webservice and receive an answert in either JSON or XML format. In boths cases, the method returns an object that represents the received information:
#DEFINE CRLF CHR(13)+CHR(10)
LOCAL oResp,cData,cHeaders
cData="q=Hello world&target=es&source=en"
cHeaders = "content-type: application/x-www-form-urlencoded" + CRLF + ;
"Accept-Encoding: application/gzip" + CRLF + ;
"X-RapidAPI-Host': google-translate1.p.rapidapi.com" + CRLF + ;
"X-RapidAPI-Key: SIGN-UP-FOR-KEY"
oResp = JSON.httpPost("ttps://google-translate1.p.rapidapi.com/language/translate/v2",cData,cHeaders)
IF NOT oResp.hasError
?oResp.JSON.message -> "You are not subscribed to this API"
ELSE
?oResp.errorMsg
ENDIF
The full syntax of httpPost() is:
resp = JSON.httpPost(cUrl [,uData], [,cContentType] [,cHeaders] [,nTimeout[)
Multiple headers can be passed using CRLF to separate them. The uData parameter can be an string or an object.
This method allows to send any kind of REST request to a webservice and receive an answer in either JSON or XML format. Both httpGet() and httpPost() methods calls this method internaly. The full sytax is:
resp = JSON.httpRequest(cVerb, cUrl [,uData], [,cHeaders] [,nTimeout[)
where cVerb can be any of these:
GET
POST
PUT
DELETE
OPTION
The resp object contains the following properties:
headers: string with the complete headers received from the server
contentType: content type of the response received
statusCode: status code received (200, 404, 500, ...)
raw: raw response received in text format
json: response parsed as an JSON or XML object
hasError: TRUE if an error ocurred with the request
errorMsg: string with the description of the error ocurred during the request
[1] The JSON string must be generated using Stringify method and INCLUDE the cursor schema. To convert other JSON strings to cursor, use toCursor().
[2] The JSON string must be an array of objects, ex:
cJSON = '[{fname: "Victor", lname: "Espina", age: 44}, {fname: "Angel", lname: "Ferreira", age: 40}]'
json.toCursor(cJSON, "qteam")
SELECT qteam
SCAN
?fname, lname, age
ENDSCAN
IF a single object is passed it would be transformed into an array before processing.
[3] All schemas has to be identified with an unique name. This name would be used later to access a particular schema, ex:
JSON.Schemas.newFromString("userInfo","login C (25), fullname C (50), pwd C (50), role C (50)")
...
JSON.Schemas.create("quser", "userInfo")
INSERT INTO quser VALUES ('vespina','Victor Espina','1234','Admin')
[4] Example:
oSchema = json.Schemas.newFromString("fname C(50), lname C(50), age N (3), dob D")
[5] Object must be an instance of jsonColumn class
[6] Example:
oSchema.addColumnFromString("lname C (50)")
[7] The optional bool parameters allows to indicate that a JSON string representation of the schema is required
[8] If optional bool parameter withSchema is passed as True, the resulting JSON string will include the cursor's schema. Use this if you plan to recreate the cursor later from the JSON string.
| Date | User | Description |
|---|---|---|
| 04/22/2024 | VES | New version 1.29. Fix on httpRequest to get the right value in RAW property for binary responses |
| 01/07/2024 | VES | New version 1.28. Fix of major bug on HTTPRequest causing any request to take AT LEAST 15s. |
| 07/31/2023 | VES | New version 1.27. Change in ToCursor() method to allow single objects |
| 06/21/2023 | VES | New version 1.26. Int values greater than VFP's max INT value are now translated as strings |
| 04/18/2023 | VES | New version 1.25. External dependencies removed to solve a problem caused by nqinclude.prg being blocked for A/V as trojan |
| 04/04/2023 | VES | New version 1.24. Fix on invalid parameter for AMEMBERS on VFP6 (thanks to Ricardo Mata) |
| 02/28/2023 | VES | New version 1.23. Fix on timeout management for httpRequest and httpGetFile methdods |
| [01/26/2022 | VES | New version 1.22. Workaround for TEXT - ENDTEXT bug in VFP6. |
| [01/26/2002 | VES | Fix on legacy ADDPROPERTY for restricted property names |
| [10/01/2022 | VES | New version 1.21. Small fix on #DEFINE VFP_JSON_BEAUTIFY_MARGIN |
| 11/26/2022 | VES | Add new normalizeResults property and results-normalizing code for fast parsing |
| 11/26/2022 | JSZ | Added iterator to JS results when fast parsing |
| 11/26/2022 | VES | New version 1.20. Fast parse mode implemented |
| 11/16/2022 | VES | New version 1.19. Changes to allow access to secured servers |
| 10/26/2022 | VES | New version 1.18. Changes on jsonColumn class to support null values |
| 5/9/2022 | VES | New version 1.17. Includes fixes on toCursor method for legacy VFP versions. |
| 4/16/2022 | VES | Support for NQInclude to automatically download any dependencies. |
| 4/6/2022 | VES | Nuevos metodos httpRequest() y httpPost(). Refactorizacion del metodo httpGet(). Mejora en metodo ParseXML() para tolerar el caracter "-" en nombres de nodo o atributos. |
| 5/29/2019 | VES | Se corrigio el problema con el metodo ToCursor() (agradecimiento especial a Fernando Puyuelo) Soporte para mensajes en espanol (por Fernando Puyuelo) |
| 5/6/2019 | AFG | Error en methodo initWithEx() de clase JSONError que usaba incorrectamente el no. de error 1525 para identificar errores de ODBC. |
| 4/25/2017 | VES | Nueva propiedad stringSeparator |
| 7/20/2016 | VES | Obviar caracters TAB en el analisis |
| 5/16/2016 | VES | Correcciones menores en metodo Stringify() |
| 12/18/2015 | VES | SingletonPattern class renamed to JSONSingletonPattern |
| 9/11/2015 | VES | Improves in Stringify() method for versions of VFP with no Empty class. |
| 8/24/2015 | VES | Improves in parseXml() method to handle repetitive sibling nodes as arrays. |
| 8/22/2015 | VES | New improved httpGet() method with XML support. New ParseXml() method. New ToXml() method |
| 8/20/2015 | VES | Fix on _parse() method for date values handling |
| 8/12/2015 | VES | New httpGet() method. Small change in Beautify() method to ensure backward compatibility. |
| 5/30/2015 | VES | Minor fixes on Parse() method for constant values like true, false or null |
| 5/3/2015 | VES | Backward compatibility with previous versions of VFP (6+) |
| 5/2/2015 | VES | Changes in Stringify() method to avoid errors while stringifying SCX files content. New property lastOpTime in json class. Changes in Stringify(), Parse() and ParseCursor() methods to implement lastOpTime property. Changes in Parse() method to support expression values |
| 5/1/2015 | VES | cursorSchemas property on json class renamed to Schemas. cursorSchemas class renamed to jsonSchemas. New method Create() in jsonSchemas class. New error (22). Several changes in jsonError class. Changed initWithDefault() with initWithEx() for CATCH error handling |
| 4/30/2015 | VES | New method toCursor() in json class. New method initWithValue() in jsonColumn. Changes in jsonColumn class's constructor. New error (21). New optional parameter pnDSID in parseCursor() method of json class. New optional parameter pnDSID in Stringify() method of json class. New optional parameter pnDSID in newFromCursor() method of jsonScheme class |
| 4/10/2015 | VES | New method initWithJSON() in jsonSchema. Update to ToString() method in jsonColumn and jsonSchema to support JSON format. Update to Stringif() in json class to optional include the schema when stringifying a cursor. New method parseCursor() in json class. New method initWithString() in jsonError class. New errors (16 to 20). New property useStrictNotation in json class. |
| 2015 | AFG | Multiple changes and fixes. Schemas implementation. |
| 2014 | VES | Initial version |