---
title: Validate JSON
type: plugins
category: Validation
cat: validation
order: 100
meta_title: Validate JSON
meta_description: Checks that the introduced text is a valid JSON
!!! note
For information about modifying this plugin or creating your own custom plugins, see Customize and Build Your Own Plugins.
For general plugin information, see [Plugins for projects](/guide/plugins) and [Plugin FAQ](faq).
This plugin parses the contexts of a TextArea field to check for valid JSON. If the JSON is invalid, it shows an error and prevents the annotation from being saved.
This is an example of a "hard" block, meaning that the user must resolve the issue before they can proceed.
LSI.on("beforeSaveAnnotation", (store, annotation) => {
const textAreaResult = annotation.results.find(r => r.type === 'textarea' && r.from_name.name === 'answer');
if (textAreaResult) {
try {
JSON.parse(textAreaResult.value.text[0]);
} catch (e) {
Htx.showModal("Invalid JSON format. Please correct the JSON and try again.", "error");
return false;
}
}
return true;
});
Related LSI instance methods:
Related frontend events:
<View>
<View>
<Filter toName="label_rectangles" minlength="0" name="filter"/>
<RectangleLabels name="label_rectangles" toName="image" canRotate="false" smart="true">
<Label value="table" background="Blue"/>
<Label value="cell" background="Red"/>
<Label value="column" background="Green"/>
<Label value="row" background="Purple"/>
</RectangleLabels>
</View>
<View>
<Image name="image" value="$image" />
</View>
<View style=".htx-text { white-space: pre-wrap; }">
<TextArea name="answer" toName="image"
editable="true"
perRegion="true"
required="false"
maxSubmissions="1"
rows="10"
placeholder="Parsed Row JSON"
displayMode="tag"/>
</View>
</View>
Related tags:
[
{
"image": "https://labelstud.io/demo/Datasets/Image/Object Detection/Image_66.jpg"
}
]