Data-connected Volto components

Volto add-on

Volto-datablocks is an addon that has various blocks and utilities to provide "data-connected" components in volto websites.

This add-on requires [email protected].

Concepts and terminology

• data-connected component: is a component or a block that displays information coming from outside sources; For example a table would get its data from a REST api server (discodata.eea.europa.eu) and show it as desired
• connector / provider: is a dexterity content type characterized by:
  • title: acts as the name of the connector and it used by plone to compose the short-name or route through which we can query the connector
  • endpoint_url: the url to the REST api server (ex. discodata.eea.europa.eu)
  • sql_query: the sql that will be executed on the REST api server
  • parameters (optional): a list of parameters (keys) through which we can filter the data fetched by the connector
  • required_parameters (optional): a list of required parameters which if not satisfed the connector will return empty data
  • collate (optional)
  • readme (optional)
• query string parameters or parameters from url; Ex. https://frontend/home?db_version=latest&p=1&nrOfHits=10
• data query are another type of parameters that are composed internally using redux
• connected data parameters is the global object that stores data queries; we will get more into this later

Workflow

A data-connected component will use a connector through which it gets its data.

eea.api.dataconnector is a plone add-on that expose an api through which a connector will run a query and fetch some data.

How to use eea.api.dataconnector

eea.api.dataconnector expose /@connector-data through which we can make POST requests to get the data of a connector. We can pass some data to the request:

• form - parameters from url
• data_query - parameters from connected data parameters

You can use this api only over connectors.

Example:

Let's say that we have the following connector added into connectors folder:

title: Forests per capita
endpoint_url: https://discodata.eea.europa.eu/sql
sql_query: SELECT * FROM [FISE].[latest].[v_cnct_forest_per_capita]
parameters: ['NUTS_CODE']

The route to the connector will be https://frontend/connectors/forests-per-capita

By making the following request:

> curl --location --request POST 'http://backend/Plone/++api++/connectors/forests-per-capita/@connector-data'

the sql_query will be executed on specified endpoint_url (discodata) and after data is fetched the response will look like:

{
   "@id": "https://backend/Plone/connectors/forests-per-capita",
   "data": {
      "metadata": {...},
      "results": {
         "COUNTRY": ["Albania", ...],
         "Forest per capita": [0.39, ...],
         "NUTS_CODE": ["AL", ...],
      }
   }
}

We can filter the data in two ways:

• By updating the sql before it is executed on discodata by adding where statements - this requires parameters property to be specified on the connector
• By filtering the data after it is fetched from discodata through for loops

Obs: both filtering are done on the backend. The response will always contain the filtered data.

In this case we can filter by NUTS_CODE. The request will look like:

> curl --location --request POST 'http://backend/Plone/++api++/connectors/forests-per-capita/@connector-data' \
--header 'Content-Type: application/json' \
--data '{
    "form": {
        "NUTS_CODE": "FR"
    }
}'

Because NUTS_CODE is specified in the parameters list of the connector the query will be modified and will look like this:

SELECT * FROM FISE.latest.v_cnct_forest_per_capita WHERE NUTS_CODE = 'FR'

So we get the data from discodata already filtered and the response will look like:

{
   "@id": "https://backend/Plone/connectors/forests-per-capita",
   "data": {
      "metadata": {...},
      "results": {
         "COUNTRY": ["France"],
         "Forest per capita": [0.23],
         "NUTS_CODE": ["FR"],
      }
   }
}

If we don't have NUTS_CODE specified in the parameters list we will still get the data filtered by NUTS_CODE but after it is fetched from discodata. So by adding keys to parameters list can dramatically decrease the data usage.

If we want to set the same parameter but through data_query the request will look like this:

> curl --location --request POST 'http://backend/Plone/++api++/connectors/forests-per-capita/@connector-data' \
--header 'Content-Type: application/json' \
--data '{
   "data_query": [
      "i": "NUTS_CODE"
      "o": "plone.app.querystring.operation.selection.any"
      "v": ["FR"]
   ]
}'

Volto-datablocks offers 4 hooks through which a data-connected component can make requests to a connector:

connectToProviderData
connectToProviderDataUnfiltered
connectToMultipleProviders
connectToMultipleProvidersUnfiltered

Obs: a data-connected component needs to specify a provider_url (the path to the connector) to the hook used to fetch the data. We will get more into this later.

Operators

Parameters from url - form

Available operators:

eq          - equal
ne          - not equal
like
not like
in
nin         - not in
gt          - greater than
gte         - greater than equal
lt          - lower than
lte         - lower than equal

To specify an operator to a parameter from url you need to use this structure:

some/path?parameter[operation]=value

For example if on the homepage we have a data-connected component that uses /connectors/forests-per-capita as provider and we want to filter it by multiple NUTS_CODE we can set a url parameter using the 'in' operator like:

https://frontend/?NUTS_CODE[in]=RO,FR

Parameters from data_query - connected_data_parameters

To be continued...

Pagination

To be continued...

Features

There are a few data-connected blocks in this add-on:

SimpleDataTable

A data-connected table which allows pagination and filtering. It can be customized by implementing a template.

TODO: tutorial on how to customize and demo

DataQueryFilter

A dropdown data-connected component that uses a provider to create a filter for it by a parameter selected from block configuration.

TODO: demo

DottedTableChart

CustomConnectedBlock

Usage (for developers)

How to connect a block to a provider?

As we said we have 4 hooks, 2 that uses filters and 2 that doesn't use filters. They require you to pass a getConfig function that returns an object. That object needs to have some specific data.

Here is the configuration needed to be passed to each hook:

1. connectToProviderData

{
   provider_url: 'path/to/provider', // mandatory
   pagination: { // optional
      enabled: true,
      itemsPerPage: 5
   }
}
// Obs: provider_url is mandatory and pagination is optional. If pagination is not configured then connectToProviderData will run as if pagination is disabled.

2. connectToProviderDataUnfiltered

{
  provider_url: 'path/to/provider'; // mandatory
}

3. connectToMultipleProviders

{
   provider: [ // mandatory
      {
         provider_url: 'path/to/provider', // mandatory
         name: 'some name', // optional
         title: 'some title', // optional
         data_query: [...some_data_query] // optional
         has_data_query_by_context: true // optional
         has_data_query_by_provider: true // optional
      }
   ]
}

4. connectToMultipleProvidersUnfiltered

{
  provider: [
    // mandatory
    {
      provider_url: 'path/to/provider', // mandatory
      name: 'some name', // optional
      title: 'some title', // optional
    },
  ];
}

Connecting to multiple providers doesn't allow pagination.

Here is an example on how to use connectToProviderData:

import React from 'react';
import { compose } from 'redux';
import { connectToProviderData } from '@eeacms/volto-datablocks/hocs';

...

const View = props => {
   ...
   return <YourComponents />
}

export default compose(
  connectToProviderData((props) => {
    return {
      provider_url: props.data?.provider_url,
    };
  }),
)(View);

Getting started

Try volto-datablocks with Docker

  git clone https://github.com/eea/volto-datablocks.git
  cd volto-datablocks
  make
  make start

Go to http://localhost:3000

Add volto-datablocks to your Volto project

1. Make sure you have a Plone backend up-and-running at http://localhost:8080/Plone

   docker compose up backend

2. Start Volto frontend

• If you already have a volto project, just update package.json:

  "addons": [
      "@eeacms/volto-datablocks"
  ],
  
  "dependencies": {
      "@eeacms/volto-datablocks": "*"
  }

• If not, create one:

  npm install -g yo @plone/generator-volto
  yo @plone/volto my-volto-project --canary --addon @eeacms/volto-datablocks
  cd my-volto-project

1. Install new add-ons and restart Volto:

   yarn
   yarn start

2. Go to http://localhost:3000

3. Happy editing!

Release

See RELEASE.md.

How to contribute

See DEVELOP.md.

Copyright and license

The Initial Owner of the Original Code is European Environment Agency (EEA). All Rights Reserved.

See LICENSE.md for details.

Funding

European Environment Agency (EU)