JSON object React component (react-json-object)

React component which renders that JSON data you kinda need to be there, but want to put zero effort into...

Objective: Make a react component for that gnarly lump of JSON.
Problem: Can't be bothered, it's not super important.
But <pre>{JSON.stringify(data, null, 4)}</pre> lowers the tone so much.
Solution <Json data={data} />!

You cannot expect it to look amazing obviously, all it can do is recurse your data and do the best it can based on it's typing.

Quick start

import Json from 'react-json-object';

function MyComponent ({ data }) {
    return (<Json data={data} />);
}

A title bar of sorts can be added to objects and arrays (containers) with a "json" button allowing the display to be toggled to JSON and back again by setting the "header" option like <Json data={data} opts={{ headers: true }}/>.

What to expect

The out of the box result, with the default CSS, is OK, if obviously highly generic, and it provides a DOM structure with a plentiful selection of classes, so you can probably quite easily tweak it to suit your particular presentation neuroses in no time at all.

If you want more, well, there are a bunch of features that let you go from there to being really unrecognisable from something you wrote entirely custom from scratch, but if you find yourself getting too far with all that you should stop to ask if you shouldn't actually do that instead; write your own components from scratch, because let's face it, turning some static data into a React component render is pretty easy...

However, the advanced customisation features, useful if you have a known schema, include path derived classes, so you can tweak the CSS of particular values without affecting others, and you can also change the React component used to render particular types or particular values (again by specified path), see details later.

You can also change what is shown for booleans and nulls instead of the default text, so you can make booleans "on" and "off" instead of "true" and "false" for example.

Default styling

Out of the box with the default CSS, the following data:

{
    "a_string": "foobar",
    "a_number": 1234,
    "an_object": {
        "another_string": "wibble",
        "another_number": 567,
        "true": true
    },
    "empty_object": {},
    "a_list": [
        "yet another string",
        "still another string",
        {
            "an": "object",
            "in_a": "list"
        },
        [
            "a",
            "list",
            "in_a",
            "list"
        ]
    ],
    "empty_list": [],
    "false": false,
    "null": null
}

Is rendered like this:

Note that you can expect all values (containers and scalars) to be rendered the the width required of by the widest peer, so they line up. This is clearly shown above. This is entirely consistent, but in some respects looks inconsistent, since some values are rendered to the full width of the container and some are not. Some simple CSS options suggested below can make all values full width, or all minimum width, though none of them will affect the top level object, the size of which is your responsibility and you should take whatever steps are appropriate to make it's size behaviour to your liking according to the other elements in play.

CSS tweaks

If you don't want the list numbering (it doesn't technically add much in most scenarios) then you can hide it with:

.rjo-array-index {
    display: none;
}

Less useful, but, you can do the same with object keys:

.rjo-object-key {
    display: none;
}

Minimising the width of values (obejcts, arrays, scalars) can be achieved with:

.rjo-container-value {
    display: inline-block;
}

Maximising them (so their boundaries reach the ends of their container elements) can be achieved with:

.rjo-container-value {
    width: 100%;
}

These effects and more may be applied in various combination to other classes, see below for a full list

DOM scheme

The general DOM structure is like this (this is for illustration only, there are other elements in between, and obviously all combinations are not shown):

<element class="rjo-json">
    <element class="rjo-json-container rjo-json-object">
        <element class="rjo-container-value rjo-object-value">
            <element class="rjo-json">
                <element class="rjo-json-value rjo-json-scalar rjo-json-string" />
            </element>
        </element>

        <element class="rjo-container-value rjo-object-value">
            <element class="rjo-json">
                <element class="rjo-json-value rjo-json-scalar rjo-json-number" />
            </element>
        </element>
    </element>

    <element class="rjo-json-container rjo-json-array">
        <element class="rjo-container-value rjo-array-value">
            <element class="rjo-json">
                <element class="rjo-json-value rjo-json-scalar rjo-json-boolean" />
            </element>
        </element>

        <element class="rjo-container-value rjo-array-value">
            <element class="rjo-json">
                <element class="rjo-json-value rjo-json-scalar rjo-json-null" />
            </element>
        </element>
    </element>
</element>

Here rjo-json is applied to an element enclosing every JSON value (first the top level value you provide, and again recursively for every string, number, boolean, null and sub objects and arrays). Each child of a rjo-json will be an element with one of these classes:

Class	Description
rjo-json-object	An object, with named keys and values
rjo-json-array	A list/array, with just (ordered) values
rjo-json-null	A null value
rjo-json-number	A number
rjo-json-boolean	A boolean

The rjo-json-object and rjo-json-array elements will also have a rjo-json-container class, and the others will have a rjo-json-scalar class. The scalars will also all have a rjo-json-value class except for rjo-json-null, since this is really not a value.

The first give lines show the nature of the recursion and repeat of the rjo-json element:

<element class="rjo-json">
    <element class="rjo-json-container rjo-json-object">
        <element class="rjo-container-value rjo-object-value">
            <element class="rjo-json">
                <element class="rjo-json-value rjo-json-scalar rjo-json-string" />

The rjo-json element contains an object, which obviously has a set of sub values, and for each there will be a container element with rjo-container-value rjo-object-value classes, which will contain another rjo-json element. A string is used here but of course it could be any JSON value, another object, an array, a number, boolean or null. Every rjo-json element may contain any of these.

Arrays are much the same, just with classes named for the "array" instead of an "object":

    <element class="rjo-json-container rjo-json-array">
        <element class="rjo-container-value rjo-array-value">
            <element class="rjo-json">
                <element class="rjo-json-value rjo-json-scalar rjo-json-boolean" />

The rjo-container-value elements enclose (are a parent of) a base rjo-json element (the only rjo-json element that will not be enclosed in a rjo-container-value element then, is the top level rjo-json element rendered for the data which you provide).

The rjo-json-path-xxxxxxxxxx class is not literal, see below for a full explanation of what xxxxxxxxxx is all about.

More elements and thus classes exist than is illustrated above, see below for a full list of classes that may be useful to target and style other elements.

CSS classes

This is a complete list of the CSS classes:

Class	Description
rjo-json	Base of every JSON value, recursively, see above
rjo-root	The top level most element
rjo-json-object	A JSON object
rjo-empty-object	An empty object
rjo-object-key	An object key
rjo-object-value	An object value
rjo-json-array	A JSON array
rjo-empty-array	An empty array
rjo-array-index	The index of an array (like an object's key)
rjo-array-value	An array value
rjo-empty-container	An empty container (object or array)
rjo-container-key	A container key/index (object key or array index)
rjo-json-string	A JSON string value
rjo-json-number	A JSON number value
rjo-json-boolean	A JSON boolean value
rjo-json-null	A JSON null value
rjo-json-container	A container value (objects and arrays)
rjo-container-value	A parent element for sub data ("rjo-json" children)
rjo-json-value	A scalar values except null
rjo-json-scalar	A scalar (all values, but not containers)
rjo-json-unknown	Should never be used

Note rjo-json-unknown should never be used, certainly nothing which was decoded from JSON could give rise to it, and also only values which would fail the prop validation should cause it to be applied, but any data type which is of unsupported type would have this class applied.

Advanced customisation

Booleans and nulls

By default booleans and shown as "true" and "false, and nulls are "none". These can be changes like this, using DOM elements, or just text:

<Json
    data={data}
    opts={{
        true: <span style={{ color: 'green' }}>yes</span>,
        false: <span style={{ color: 'red' }}>no</span>,
        null: 'N/A',
    }}
/>

Unique path derived CSS classes

There is a rjo-json-path-xxxxxxxxxx class applied to every rjo-json element, and the xxxxxxxxxx is not literal, it is generated depending on the path of the JSON data being rendered.

The top level rjo-json element will be rendered with an additional class of rjo-json-path, and every ultimate child will be rendered with a unique path class recursively based on the path through the JSON to it from the top level.

Taking a part of the example data used above:

{
    "a_string": "foobar",
    "a_list": [
        "yet another string",
        "still another string",
        {
            "an": "object",
            "in_a": "list"
        },
        [
            "a",
            "list",
            "in_a",
            "list"
        ]
    ],
}

The rjo-json element for the a_string value of the root object would have an additional rjo-path-a_string class applied.

The third list item in the second list item of the a_list value of the root object is a scalar string value "in_a". The associated rjo-json element would have four additional classes applied:

rjo-path-a_list-n-n
rjo-path-a_list-n-2
rjo-path-a_list-3-n
rjo-path-a_list-3-2

This is because the ordering of an array may or may not matter, it depends on the data, but with these classes it is possible to target a particular list item or any item of a given list. This would result in a lot of classes if you have a lot of lists of lists of lists, 2 nested lists results in 4 classes, no problem, but 10 nested lists will result in 1024 classes! This isn't an obviously likely scenario for normal use of the component, but you can change this behaviour so that it just applies numbered classes, or just unnumbered, either of which means 10 nested lists will be a very manageable 10 classes.

To do opt for just rjo-path-a_list-3-2 in the example above, do:

<Json data={data} opts={{ array_path_classes: 'numbered' }} />

To do opt for just rjo-path-a_list-n-n in the example above, do:

<Json data={data} opts={{ array_path_classes: 'unnumbered' }} />

Changing the components

If you just want to:

Change the React component used to render a particular data type...
Change it for the fourth item of the list in the "wibble" value of an object...
Pick through the data itself and choose a component...

...all this is possible.

By default, the component used is chosen purely based on the data type (object, array, string, number, boolean or null). To superceed this behaviour simply provide a function which returns an alternative component. The function will be passed the data type, the path and the data itself. If the function returns undefined, then the default behaviour will be resumed. If the function returns null, then no render for the value is performed. Otherwise, the value will be taken to be a React component.

Your function should be provided as follows:

<Json data={data} component={componentSwitch} />

The function should look like this:

function component(dataType, path, data) {
}

The dataType parameter will be a string, "object", "array", "string", "number", "boolean" or "null".

The path parameter will be a list of path elements. For the top level render (the data prop passed to the Json component) this will be an empty list. If data is an object then for the wibble key, the path will be ['wibble']. If wibble is in turn a list, then the fourth item will have a path of ['wibble', 3]. You can tell the second part of the path is a list element because it is a number not a string.

The data parameter is of course the actual data.

NOTE! If you replace the render of a container (an object or array) your replacement must render all the data, the container, it's children, grand children, etc. This is almost always what you want in this situation, but if you want to provide a wrapper and invoke the normal Json React component render for child or grand child elements, then you could do something like this:

import Json from 'react-json-object';

function MyJsonComponent({ data, path, component, opts }) {
    return (
        <MyWrapper>
            <Json data={data} path={newPath(path)} component={component} opts={opts} />
        </MyWrapper>
    );
}

function componentSwitch(dataType, path, data) {
    return shouldUseMyComponent(dataType, path, data)
        ? MyJsonComponent
        : null;
}

...and invoke the Json component like <Json component={componentSwitch} />.

You are burdened with safely reintegrating back into the recursion in a seemless and sensible way however. There are four props passed to Json above, data is obviously the data you want Json to take on and render, path should be an extended path, you should append one or more strings and integers to it to represent the change in path from your component to the child you are delegating to Json. The component and opts can and probably should be simply passed through. Note that opts will be an object and expanded to include defaults.

Note that prop types are ommitted above, but here's a nice contrived full working example which serves up various very silly contrived madness and includes everything:

import {
    Json, jsonDataOptsPropType, jsonDataPathPropType, jsonDataPropType,
} from 'react-json-object';

// use a green unicode tick or a red unicode cross for boolean true/false rendition
// this could just be done with opts.true and opts.false, but this is a contrived example
function MyBoolJsonComponent({ data }) {
    return data
        ? <b style={{ color: 'green', fontSize: '150%' }}>{'\u2713'}</b>
        : <b style={{ color: 'red', fontSize: '150%' }}>{'\u2718'}</b>;
}

MyBoolJsonComponent.propTypes = {
    data: PropTypes.bool.isRequired,
};

// wrap the standard <Json/> component with one which has a yelloe background
function MyYellowJsonComponent({
    data, path, component, opts,
}) {
    return (
        <div style={{ backgroundColor: 'yellow' }}>
            <Json data={data} path={path.concat(['yellow'])} component={component} opts={opts} />
        </div>
    );
}

MyYellowJsonComponent.propTypes = {
    data: PropTypes.bool.isRequired,
    path: jsonDataPathPropType.isRequired,
    component: PropTypes.func.isRequired,
    opts: jsonDataOptsPropType.isRequired,
};

// wrap the standard <Json/> component with a black frame
function MyBlackFrameJsonComponent({
    data, path, component, opts,
}) {
    return (
        <div style={{ backgroundColor: 'black', padding: '0.3em' }}>
            <Json data={data} path={path.concat(['blackframe'])} component={component} opts={opts} />
        </div>
    );
}

MyBlackFrameJsonComponent.propTypes = {
    data: PropTypes.bool.isRequired,
    path: jsonDataPathPropType.isRequired,
    component: PropTypes.func.isRequired,
    opts: jsonDataOptsPropType.isRequired,
};

// raw JSON rendering
function MyRawJsonComponent({ data }) {
    return (
        <pre style={{ border: '4px dashed black', padding: '0.2em', margin: 0 }}>
            {JSON.stringify(data, null, 4)}
        </pre>
    );
}

MyRawJsonComponent.propTypes = {
    data: PropTypes.bool.isRequired,
};

// wrap the standard <Json/> component with a black frame
function MyNumberMultiplierJsonComponent({
    data, path, component, opts,
}) {
    let data2 = data;
    if (data < 10000) { data2 = data * 10; }

    return (
        <Json data={data2} path={path.concat(['times2000'])} component={component} opts={opts} />
    );
}

MyNumberMultiplierJsonComponent.propTypes = {
    data: PropTypes.bool.isRequired,
    path: jsonDataPathPropType.isRequired,
    component: PropTypes.func.isRequired,
    opts: jsonDataOptsPropType.isRequired,
};

function componentSwitch(dataType, path, data) {
    // render all booleans with the MyBoolJsonComponent component
    if (dataType === 'boolean') {
        return MyBoolJsonComponent;
    }
    // render the third item of the "a_list" property with the MyYellowJsonComponent component
    if (path.join('-') === 'a_list-3') {
        return MyYellowJsonComponent;
    }
    // render the second item of the "a_list" property with the MyRawJsonComponent component
    if (path.join('-') === 'a_list-2') {
        return MyRawJsonComponent;
    }
    // render the first item of every list with the MyBlackFrameJsonComponent component
    if (path[path.length - 1] === 0) {
        return MyBlackFrameJsonComponent;
    }
    // render any odd numbers with the MyNumberMultiplierJsonComponent component
    if (dataType === 'number' && data % 2 !== 0) {
        return MyNumberMultiplierJsonComponent;
    }
    // everything else, just do the default
    return undefined;
}

// Compose all this in a MyJson component with some other custom options as well.
function MyJson({ data }) {
    return (
        <Json
            data={data}
            opts={{ null_text: 'not applicable' }}
            component={componentSwitch}
        />
    );
}

// Again, composing this way way clearly implies the data type is known, so almost
// certainly something more precise than jsonDataPropType would be appropriate.
MyJson.propTypes = {
    data: jsonDataPropType.isRequired,
};

Taking up the same example data employed earlier again:

const data = {
    "a_string": "foobar",
    "a_number": 1234,
    "an_object": {
        "another_string": "wibble",
        "another_number": 567,
        "true": true
    },
    "empty_object": {},
    "a_list": [
        "yet another string",
        "still another string",
        {
            "an": "object",
            "in_a": "list"
        },
        [
            "a",
            "list",
            "in_a",
            "list"
        ]
    ],
    "empty_list": [],
    "false": false,
    "null": null
}

Rendering using MyJson instead of Json should look like this:

<MyJson data={data} />

Name		Name	Last commit message	Last commit date
Latest commit History 8 Commits
.github/workflows		.github/workflows
dist		dist
src		src
.eslintrc.json		.eslintrc.json
.gitignore		.gitignore
LICENSE		LICENSE
Makefile		Makefile
README.md		README.md
babel.config.json		babel.config.json
example.png		example.png
example_madness.png		example_madness.png
gruntfile.js		gruntfile.js
package-lock.json		package-lock.json
package.json		package.json

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JSON object React component (react-json-object)

Quick start

What to expect

Default styling

CSS tweaks

DOM scheme

CSS classes

Advanced customisation

Booleans and nulls

Unique path derived CSS classes

Changing the components

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mwri/react-json-object

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JSON object React component (react-json-object)

Quick start

What to expect

Default styling

CSS tweaks

DOM scheme

CSS classes

Advanced customisation

Booleans and nulls

Unique path derived CSS classes

Changing the components

About

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