json — n_pbt_json #

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Build a JSON type by type — string, number, boolean, array, nested object — with the escaping done for you, then read one back along a path: of_load, of_get_string, of_type, of_count. A single object builds your requests and reads your responses. All in pure PowerScript: no page, no engine, PowerBuilder 10 included.

▶ See it live — Demo application, JSON tile: the results, the code behind them and this page, side by side.

At a glance #

n_pbt_json is autoinstantiate: declare it as a local variable, no create or destroy. It is the very object that internally builds the payloads sent to the engine — now offered to your code, on the build and the read side.

Quick start #

Build a payload, then read a response back — it all fits in one local variable:

// Local variables
n_pbt_json  lnv_json
string      ls_customer
double      ld_total

// Write : each member is typed and escaped for you - a path may have levels
lnv_json.of_set_string(/*path*/ "customer", /*value*/ "Ada")
lnv_json.of_set_number(/*path*/ "total", /*value*/ 690.50)
lnv_json.of_set_boolean(/*path*/ "paid", /*value*/ true)

// lnv_json.of_text() -> {"customer":"Ada","total":690.5,"paid":true}

// Read : load a response, reach values by path
lnv_json.of_load(/*json*/ '{"order":{"customer":"Ada","total":690.50}}')
IF lnv_json.of_is_valid() THEN
	ls_customer = lnv_json.of_get_string(/*path*/ "order/customer")   // Ada
	ld_total    = lnv_json.of_get_number(/*path*/ "order/total")     // 690.5
END IF

A path is the keys from the root joined by /; an array index is its position, counted from 1, like every position of the library: order/lines/1 is the first line, order/lines/0 addresses nothing. An empty segment (a//b, /a) or an index 0 on an array addresses nothing — a write refuses it with -5 — and a key that holds a / cannot be addressed. When an object writes the same key twice, its FIRST occurrence is the one read and written — a browser keeps the last one.

Build a payload #

Read a document #

// Local variables
n_pbt_json  lnv_json
string      ls_tags[]
string      ls_compact
long        ll_count

// Read every element of an array at once, then store the document on one line
lnv_json.of_load(/*json*/ '{"customer":{"name":"Ada","tags":["vip","b2b"]}}')
ll_count = lnv_json.of_get_array(/*path*/ "customer/tags", /*values*/ ls_tags)   // 2 : vip, b2b

// The document on one line, without a space : the smallest text to store
ls_compact = lnv_json.of_pretty(/*indent*/ 0)

Modify a document #

The write side changes the loaded document in place, then of_text returns the result (compact) — what to save back. The setters replace the value at the path, or add the last key when it is missing from a parent object. Each returns 0, -4 when the parent is missing or of the wrong type, -5 on an empty path or an index 0 on an array. An array met on the way is crossed by an index that EXISTS (items/1/qty adds qty to the first element); only an object key is ever created. A null value (number, boolean, empty raw JSON) is written null.

// Local variables
n_pbt_json  lnv_json

// Load, edit in place, then read back the ONE document with of_text
lnv_json.of_load(/*json*/ '{"name":"Ada","active":false}')
lnv_json.of_set_string(/*path*/ "name", /*value*/ "Grace")   // replace
lnv_json.of_set_boolean(/*path*/ "active", /*value*/ true)
lnv_json.of_set_number(/*path*/ "count", /*value*/ 3)        // added : the key was absent

// lnv_json.of_text() -> {"name":"Grace","active":true,"count":3}

Scope. JSON parses in pure PowerScript, no page or engine: n_pbt_json stays autoinstantiate and works everywhere, PowerBuilder 10 included. For XML, see xml (which relies on the engine); to display a JSON as a collapsible tree, see jsontree.

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