It's a drop in replacement for json.Unmarshal and you can typically see
a 3 to 4 times boost in performance without the need for external tools
or generators.
This function works almost identically to json.Unmarshal except that
it expects the json to be well-formed prior to being called. Invalid
json will not panic, but it may return back unexpected results.
Therefore the return value of this function will always be nil.
Another difference is that gjson.Unmarshal will automatically attempt
to convert JSON values to any Go type. For example, the JSON string
"100" or the JSON number 100 can be equally assigned to Go string,
int, byte, uint64, etc. This rule applies to all types.
This commit alters the behavior of string handling.
Prior to this change, calling result.String() for nonexistent and null
JSON members would return "null". This runs counter to the zero and omitempty
defaults of Go. Thus I've been seeing in the wild:
s := result.String()
if s == "null" || s == "" {
// ... handle empty string condition
}
Now we can simply write:
if result.String() == "" {
// ... handle empty string condition
}
It's still possible to explicitly check for null and existence.
result.Type == gjson.Null
result.Exists()
It's now possible to query an array for multiple matches by adding the
'#' character immediately following the query.
For example, using the following JSON:
{
"friends": [
{"first": "Dale", "last": "Murphy"},
{"first": "Roger", "last": "Craig"},
{"first": "Jane", "last": "Murphy"}
]
}
To return the first match:
`friends.#[last="Murphy"].first` >> "Dale"
To return all matches:
`friends.#[last="Murphy"]#.first` >> ["Dale","Jane"]
Thanks to @chuttam for requesting this feature, closes#15.
The `GetMany(json, paths...)` function can be used to get multiple
values at one time from the same json string.
This is preferrable to calling `Get(json, path)` over and over.
It's also optimized to scan over a JSON payload once.
This addresses a feature request by @FZambia, and closes#13.
