JSONGETVALUE Function

目的

Reads a value from a JSON text.

構文

JSONGETVALUE(p,l[,v])

Parameters

p

A pointer specifying the address of the JSON text buffer.

l

Specifies the length in bytes of the JSON text buffer.

v

A reference to a PL/I variable, which may be scalar, array, or a structure or a combination.If it is a structure, it must not contain any elements that have * names, have UNION or GRAPHIC attributes, are scaled FIXED BINARY, or are FIXED DECIMAL (p, q) where q < 0 or q > p.

Description

JSONGETVALUE reads a value (value in name-value pair) from the JSON text buffer and returns the number of bytes read.A JSON value may be one of following:

• A number (integer, decimal number, or floating pint number), e.g. 345.67.It typically maps to any arithmetic item
• A string, which must be enclosed in double quotes e.g. "San Francisco".It typically maps to any character item (VARYING, NONVARYING, VARYINGZ)
• true (all lowercase) for boolean value that is true, typically mapping to BIT
• o false (all lowercase) for boolean value that is false, typically mapping to BIT
• o null (all lowercase) for a null value that will not be assigned to the variable

Examples of name-value pairs include:

• 6
• [ 1, 2, 3, 4, 5 ]
• {"D2": 2, "D5": 5}

• [
       { "No": 1, "Name": "Accident","Place": "Maryland", "Really":true},
       { "No": 2, "Name": "Boring",  "Place": "Oregon",  "Really": true},
       { "No": 3, "Name": "Dull",    "Place": "Scotland","Really": true},
       { "No": 4, "Name": "Noplace", "Place": "England","Really": false},
       { "No": 5, "Name": "Why",     "Place": "Arizona", "Really": true},
       { "No": 6, "Name": "Zzyzx",   "Place":"California","Really":true}
  

The ERROR condition is raised if the JSON text is invalid (for example, the value is invalid, etc.).The ONCODE built-in function tells you why the ERROR condition was raised and the ONSUBCODE built-in function will give you the position of the invalid character, which you can use to examine the invalid character and/or replace it with a valid character.

If the third argument is omitted, the data read is effectively thrown away.If the third argument is present, the data is assigned (after appropriate conversions) to the PL/I variable(s).If the variable has the CHARACTER type, it is converted from UTF-8 to character before assignment.

例

For a complete program using various JSON built-in functions, see the last example under JSONPUTVALUE.

例 1：

 Dcl Array(5) fixed bin(31);

例 2：

Dcl Towns fixed bin(31);

例 3：

Suppose the buffer (pointed to by bufp) contains

{"FD":[ {"D2": 2, "D5": 5}, {"D2": 4, "D5": 9}]}, then bytes = jsongetvalue(bufp, bufl s3); will assign data to the structure S3.

dcl 1 S3,
       2 fd(2),
         3 d2 fixed bin(15),
         3 d5 fixed dec(7);

制限事項

なし。