llJsonGetValue
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Summary
Function: string llJsonGetValue( string json, list specifiers );| ? | Function ID |
| 0.0 | Forced Delay |
| 10.0 | Energy |
Gets the value indicated by specifiers from the json string.
Returns a string made by parsing json, a string representing json and traversing as specified by specifiers.
| • string | json | |||
| • list | specifiers |
When the input is invalid or no result can be found this function returns JSON_INVALID. If the result is null the function returns JSON_NULL.
Specification
Caveats
llJsonGetValue() is significantly slower than reading a value from a list with llList2String(). And llJsonGetValue() gets exponentially worse for with longer lists/arrays.
Reading all single values from a Json with llJsonGetValue() takes roughly 0.5*values times as long as reading all single values from a list with llList2String().
- This means; a Json with 10 values takes 2x as long to read an average value from, than reading an average value from a list with 10 entries.
- This means; a Json with 100 values takes 20x as long to read an average value from, than reading an average value from a list with 100 entries.
"average values" because it appears that reading a right value with a high specifier# from a Json takes longer than reading a value with a low specifier# from a Json. The "left values" get read faster, but still read slower than any from a list, where value# does not seem to matter at all for reading speed.
Examples
<lsl> JGetValTest(){
string j="[[1,2],[4,5,6]]"; //JSON may be written directly as a string like this in sl. string k; //this will change with each command below; k=llJsonGetValue(j,[]); //returns the whole array of a JSON. It might just be one entry or a whole nested array or whole nested object. //if "j" is a single JSON_STRING, this may return what the string represents as a JSON within a string; a JSON_NUMBER , JSON_TRUE, TRUE ...
k=llJsonGetValue("\"3.14\"",[]); //==k="3,14" (float that was stored in a JSON_STRING within a JSON. and not as JSON_NUMBER for no good reason)
k=llJsonGetValue("\"TRUE\"" ,[]); //==k="TRUE" (the value was stored as a JSON_STRING and is thus returned verbatim)
k=llJsonGetValue(j,[0]); //returns only the first entry (at offset 0). An entry can be any JSON type,
//each entry being separated by a comma from other entries.
//array and object entries may contain multiple comma separated entries within them.
k=llJsonGetValue(j,[1]);//returns only the second entry... (all the above still applies) k="[4,5,6]";
k=llJsonGetValue(llJsonGetValue(j,[1]),[2]);
//instead of getting an entry from "j" we get a sub-entry from llJsonGetValue(j,[1]),
//assuming the sub-entry is a JSON_ARRAY. It returns the 3rd sub-entry of the second entry,
//that is an array with 3 entries. it would make k="6".
//it will return JSON_INVALID if there is no 3rd entry in the 2nd sub-array,
//or no 2nd sub-array.
k=llJsonGetValue(j,[1,2]); //Shorter way to do the same as in the previous example.
k=llJsonGetValue("true",[]); //Sets k to JSON_TRUE
k=llJsonGetValue("True",[]); //Sets k to JSON_INVALID because the JSON constant for 'true' is all lower case
k=llJsonGetValue("TRUE",[]); //Sets k to JSON_INVALID because the JSON constant for 'true' is all lower case
k=llJsonGetValue(JSON_TRUE,[]); //Sets k to JSON_INVALID. The JSON_xxxx constants are not supposed to be part of
// a JSON string, just values to test against.
} </lsl>
See also llJsonValueType for examples where the value type is checked before getting the value as that type.See Also
Deep Notes
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BUG-3692 | A |
Signature |
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function string llJsonGetValue( string json, list specifiers ); |