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Updated FAQ (markdown)

Benoît Blanchon
2016-02-28 17:35:18 +01:00
parent 6958c29cfe
commit d3dd10fa0f
1 changed files with 13 additions and 4 deletions
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17
FAQ.md

@@ -64,11 +64,20 @@ The parsing functions, `parseArray()` and `parseObject()`, may fail for 3 reason
1. The input is not a valid JSON
2. The `StaticJsonBuffer` is too small
3. The `DynamicJsonBuffer` fails to allocate memory
3. The `StaticJsonBuffer` is too big (stack overflow)
4. The `DynamicJsonBuffer` fails to allocate memory
If you're is case 2., you can solve the problem by increasing the size of the `StaticJsonBuffer`or by switching to a `DynamicJsonBuffer`.
Case 1. seems obvious, but a lot of issues are caused by from an invalid input.
In particular, if you're writing an HTTP client, you need to skip the HTTP headers and send only the JSON payload to ArduinoJson.
See issues [#108](https://github.com/bblanchon/ArduinoJson/issues/108), [#167](https://github.com/bblanchon/ArduinoJson/issues/167), [#218](https://github.com/bblanchon/ArduinoJson/issues/218) and [#237](https://github.com/bblanchon/ArduinoJson/issues/237)
If you're in case 3., you may have a memory leak, it up to you to find it. You can try to switch to `StaticJsonBuffer` which is more efficient.
If you're in case 2., you can solve the problem by increasing the size of the `StaticJsonBuffer` or by switching to a `DynamicJsonBuffer`.
See issues [#53](https://github.com/bblanchon/ArduinoJson/issues/53), [#89](https://github.com/bblanchon/ArduinoJson/issues/89) and [#202](https://github.com/bblanchon/ArduinoJson/issues/202).
If you're in case 3., you can try to switch to a `DynamicJsonBuffer`. Indeed, most platforms have a fixed size of the stack (usually 4KB on the ESP8266) the rest of the RAM being reserved to the heap. That's why moving the `JsonBuffer` from the stack to the heap can solve this kind of problem.
See issues [#167](https://github.com/bblanchon/ArduinoJson/issues/167) and [#234](https://github.com/bblanchon/ArduinoJson/issues/234).
If you're in case 4., you may have a memory leak, it up to you to find it. You can try to switch to `StaticJsonBuffer` which is more efficient.
Also, if the input string is constant, the `JsonBuffer` will have to make a copy of it.
@@ -88,7 +97,7 @@ jsonBuffer.parseObject(json);
To avoid any duplication, make sure you use an input of type `char*` or `char[]`
See issues [#53](https://github.com/bblanchon/ArduinoJson/issues/53), [#89](https://github.com/bblanchon/ArduinoJson/issues/89), [#108](https://github.com/bblanchon/ArduinoJson/issues/108), [#153](https://github.com/bblanchon/ArduinoJson/issues/153), [#154](https://github.com/bblanchon/ArduinoJson/issues/154), [#167](https://github.com/bblanchon/ArduinoJson/issues/167), [#168](https://github.com/bblanchon/ArduinoJson/issues/168), [#172](https://github.com/bblanchon/ArduinoJson/issues/172), [#177](https://github.com/bblanchon/ArduinoJson/issues/177), [#179](https://github.com/bblanchon/ArduinoJson/issues/179), [#202](https://github.com/bblanchon/ArduinoJson/issues/202) and [#223](https://github.com/bblanchon/ArduinoJson/issues/223).
See issues [#154](https://github.com/bblanchon/ArduinoJson/issues/154), [#177](https://github.com/bblanchon/ArduinoJson/issues/177), [#179](https://github.com/bblanchon/ArduinoJson/issues/179) and [#223](https://github.com/bblanchon/ArduinoJson/issues/223).
### The first parsing succeeds, why does the next ones fail?