This example demonstrates the creation of a custom flow element which takes the results of a client side form collecting date of birth, setting this as evidence on a flowData object to calculate a person's starsign.The flowElement also serves additional JavaScript which gets a user's geolocation and saves the latitude as a cookie. This latitude is also then passed in to the flowData to calculate if a person is in the northern or southern hemispheres.
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// First require the core Pipeline
// Note that this example is designed to be run from within the
// source repository. If this code has been copied to run standalone
// then you'll need to replace the require below with the commented
// out version below it.
const FiftyOnePipelineCore = require(
(process.env.directory || __dirname) + '/../../'
);
// const FiftyOnePipelineCore = require("fiftyone.pipeline.core");
// Function to get star sign from month and day
const getStarSign = (month, day) => {
if ((month === 1 && day <= 20) || (month === 12 && day >= 22)) {
return 'capricorn';
} else if ((month === 1 && day >= 21) || (month === 2 && day <= 18)) {
return 'aquarius';
} else if ((month === 2 && day >= 19) || (month === 3 && day <= 20)) {
return 'pisces';
} else if ((month === 3 && day >= 21) || (month === 4 && day <= 20)) {
return 'aries';
} else if ((month === 4 && day >= 21) || (month === 5 && day <= 20)) {
return 'taurus';
} else if ((month === 5 && day >= 21) || (month === 6 && day <= 20)) {
return 'gemini';
} else if ((month === 6 && day >= 22) || (month === 7 && day <= 22)) {
return 'cancer';
} else if ((month === 7 && day >= 23) || (month === 8 && day <= 23)) {
return 'leo';
} else if ((month === 8 && day >= 24) || (month === 9 && day <= 23)) {
return 'virgo';
} else if ((month === 9 && day >= 24) || (month === 10 && day <= 23)) {
return 'libra';
} else if ((month === 10 && day >= 24) || (month === 11 && day <= 22)) {
return 'scorpio';
} else if ((month === 11 && day >= 23) || (month === 12 && day <= 21)) {
return 'sagittarius';
}
};
// Astrology flowElement
constructor () {
super(...arguments);
// datakey used to categorise data coming back from this
// flowElement in a pipeline
this.dataKey = 'astrology';
// A filter (in this case a basic list) stating which
// evidence the flowElement is interested in
this.evidenceKeyFilter = new FiftyOnePipelineCore
.BasicListEvidenceKeyFilter(
['cookie.latitude', 'query.dateOfBirth']
);
// The properties list includes extra information about
// the properties available from a flowElement
this.properties = {
hemisphere: {
type: 'string',
description: "the user's hemisphere"
},
starSign: {
type: 'string',
description: "the user's starsign"
},
getLatitude: {
type: 'javascript',
description: "JavaScript used to get a user's latitude"
}
};
}
// The processInternal function is the core working of a
// flowElement. It takes flowData, reads evidence and returns data.
processInternal (flowData) {
const result = {};
// Get the date of birth from the query string
// (submitted through a form on the client side)
let dateOfBirth = flowData.evidence.get('query.dateOfBirth');
if (dateOfBirth) {
dateOfBirth = dateOfBirth.split('-');
const month = parseInt(dateOfBirth[1]);
const day = parseInt(dateOfBirth[2]);
result.starSign = getStarSign(month, day);
}
// Get the latitude from the a cookie if client side
// JavaScript to set the user's latitude has run
const latitude = flowData.evidence.get('cookie.latitude');
if (!latitude) {
// If no cookie set, add client side javascript to set the cookie with
// the user's latitude.
// Note that the text '// 51D replace this comment
// with callback function.'
// will be replaced with a callback to indicate once the value has
// been set.
// This can trigger another request to the web server with the additional
// information, which can then be processed and used to update the
// JSON data on the client.
result.getLatitude = `
navigator.geolocation.getCurrentPosition(function(position)
{ document.cookie = 'latitude=' + position.coords.latitude;
// 51D replace this comment with callback function.
});
`;
} else {
// Calculate the hemisphere
result.hemisphere = latitude > 0 ? 'Northern' : 'Southern';
}
// Save the data into an extension of the
// elementData class (in this case a simple dictionary subclass)
const data = new FiftyOnePipelineCore.ElementDataDictionary({
flowElement: this,
contents: result
});
// Set this data on the flowElement
flowData.setElementData(data);
}
}
const http = require('http');
const pipeline = new FiftyOnePipelineCore.PipelineBuilder({
javascriptBuilderSettings: {
endPoint: '/json'
}
})
.add(element)
.build();
const server = http.createServer((req, res) => {
const flowData = pipeline.createFlowData();
// Add any information from the request
// (headers, cookies and additional client side
// provided information)
flowData.evidence.addFromRequest(req);
flowData.process().then(function () {
// Send back JSON if requesting it from the client side
// via the JavaScriptBuilder
if (req.url.indexOf('/json') !== -1) {
res.statusCode = 200;
res.setHeader('Content-Type', 'application/json');
res.end(JSON.stringify(flowData.jsonbundler.json));
return;
}
// Place JavaScript on the page that gets the user's location
// and saves the latitude in a cookie (for working out the hemisphere).
const js = flowData.javascriptbuilder.javascript;
const output = `
<h1>Starsigns</h1>
${
flowData.astrology.starSign
? '<p>Your starsign is ' + flowData.astrology.starSign + ' </p>'
: '<p>Add your date of birth to get your starsign</p>'
}
<div id="hemispheretext">
${
flowData.astrology.hemisphere
? '<p>Look at the ' +
flowData.astrology.hemisphere +
' hemisphere stars tonight</p>'
: ''
}
</div>
<form><label for='dateOfBirth'>Date of birth</label>
<input type='date' name='dateOfBirth' id='dateOfBirth'>
<input type='submit'></form>
<script>
${js}
// This function will fire when the JSON data object is updated
// with information from the server.
// The sequence is:
// 1. Response contains JavaScript property 'getLatitude'
// that gets executed on the client
// 2. This triggers another call to the webserver
// that passes the location as evidence
// 3. The web server responds with new JSON data
// that contains the hemisphere based on the location.
// 4. The JavaScript integrates the new JSON data and
// fires the onChange callback below.
window.onload = function() {
fod.complete(function (data) {
console.log(data);
if(data.astrology.hemisphere) {
var para = document.createElement("p");
var text = document.createTextNode("Look at the " +
data.astrology.hemisphere + " hemisphere tonight");
para.appendChild(text);
var element = document.getElementById("hemispheretext");
var child = element.lastElementChild;
while (child) {
element.removeChild(child);
child = element.lastElementChild;
}
element.appendChild(para);
}
});
}
</script>
`;
res.statusCode = 200;
res.setHeader('Content-Type', 'text/html');
res.end(output);
});
});
const portNum = process.env.PORT || 3000;
console.info('To test this example, browse to http://localhost:' + portNum);
server.listen(portNum);