Converting JsonValue to String

[heykirby]

Simdjson cannot compress structures
for example json
{ "field1": { "field2": "xx" } }
I cannot get the compressed value for field1, value is { "field2": "xx" }

[piotrrzysko]

Do I understand correctly that you would like to read the value of field1 as a string? Something like this:

JsonValue json = parser.parse(...);
Iterator<Map.Entry<String, JsonValue>> it = json.objectIterator();
Map.Entry<String, JsonValue> field1 = it.next();
System.out.println(field1.getValue().asString()); // this prints '{ "field2": "xx" }'

[heykirby]

yes, it looks like simdjson has implemented this capability，thanks

[andyglow]

for me field1.getValue().asString() doesn't work if the value is either <array> or <object>
gets me something like this instead

Caused by: java.lang.StringIndexOutOfBoundsException: Range [3198, 3198 + 1952541807) out of bounds for length 35651584
         at java.base/jdk.internal.util.Preconditions$1.apply(Preconditions.java:55)
         at java.base/jdk.internal.util.Preconditions$1.apply(Preconditions.java:52)
         at java.base/jdk.internal.util.Preconditions$4.apply(Preconditions.java:213)
         at java.base/jdk.internal.util.Preconditions$4.apply(Preconditions.java:210)
         at java.base/jdk.internal.util.Preconditions.outOfBounds(Preconditions.java:98)
         at java.base/jdk.internal.util.Preconditions.outOfBoundsCheckFromIndexSize(Preconditions.java:118)
         at java.base/jdk.internal.util.Preconditions.checkFromIndexSize(Preconditions.java:397)
         at java.base/java.lang.String.checkBoundsOffCount(String.java:4849)
         at java.base/java.lang.String.<init>(String.java:522)
         at org.simdjson.JsonValue.getString(JsonValue.java:87)
         at org.simdjson.JsonValue.asString(JsonValue.java:81)

[piotrrzysko]

The snippet I provided in the previous comment was just to verify if I understand the issue correctly. I'm not saying that currently this line works according to the comment:

System.out.println(field1.getValue().asString()); // this prints '{ "field2": "xx" }'

[andyglow]

gotcha. are there plans to make asString handle these scenarios, @piotrrzysko ?
in some cases it would be great to be able to reuse original slice of buffer to stringify the value instead of building a new one traversing the value

[piotrrzysko]

I think we can try to add it. However, I'm currently busy working on #35, so I can't promise when I'll be able to do that.

[andyglow]

I see. That would be wonderful if you could make it happen at some point. I'll be waiting for it :)

[andyglow]

hello @piotrrzysko. a gentle reminder that this feature still highly anticipated and appreciated :)

[heykirby]

@andyglow refer to #59 ,it works for us，and might work for you too

[matkt]

I’m really interested in this project and was wondering if there’s been any progress on this issue or if someone is currently working on it. The ability to convert to a string would be extremely helpful.
Thanks for your hard work and for any update you can provide!

[heykirby]

I’m really interested in this project and was wondering if there’s been any progress on this issue or if someone is currently working on it. The ability to convert to a string would be extremely helpful. Thanks for your hard work and for any update you can provide!

#63 hello,it may be work for you

[piotrrzysko]

The ability to convert to a string would be extremely helpful.

Just out of curiosity: why could this feature be useful? What are the use cases?

[heykirby]

The ability to convert to a string would be extremely helpful.

Just out of curiosity: why could this feature be useful? What are the use cases?

hello，piotrrzysko，use cases can be found in #63 src/test/java/org/simdjson/demand/PathsBasedTest.java.
When constructing an instance of PathsBasedJsonParser, simply pass the path to be parsed as a constructor argument. If the corresponding path is of type map or array, it will automatically be compressed into a string. Both keys and indexes of maps and arrays are supported in the paths to be parsed
for example, json like

PathsBasedJsonParser parser = new PathsBasedJsonParser("a.b", "a.b.c", "d.[0]", "d", "d.[0].f");   
String[] values = parser.parse(json);  
// values = ["{\"c\":\"value1\"}", "value1", "{\"e\":1}", "[{\"e\":1},{\"f\":2.1}]", "2.1"]  

you can also specify the type of the value you want to parse. This is useful when you want to ensure that the value you are parsing is of a certain type, string type default if not assign.

PathsBasedJsonParser parser = new PathsBasedJsonParser( "d.[0].e:INT", "d.[0].f:DOUBLE");  
Object[] values = parser.parse(json);  
// values = [1, 2.1]. 

it's important to note that when referring to array indices, they should be enclosed within square brackets []. If a map key contains square brackets, they need to be written twice as a backslash is used to escape them.
for example,if json like this,we can get $.a.[b.c] like

PathsBasedJsonParser parser = new PathsBasedJsonParser( "a.[[b.c]]");  
String[] values = parser.parse(json);  
// values = ["value1"].