Trying to pass a session variable from a php file into a javascript file

Question

I am coding a php application which uses the D3 observable collapsible tree. A json file is created by php which is accessed by a .js file.

The relevant line in the .js which sets the file path to the json file is;

const fileAttachments = new Map([["flare-2.json",new URL("../files/paul",import.meta.url)]]);

This is working fine.

However, I want to have multiple users on the site, each with a separate json file. Therefore the .js file will need to dynamically access a different file path, depending on the user.

The php that creates the session file path is;

$file_path = "../files/$user";
$_SESSION['file_path'] = $file_path;

I have modified the .js as follows;

 const fileAttachments = new Map([["flare-2.json",new URL("<?php session_start(); $file_path = $_SESSION['file_path']; echo $file_path;?>", import.meta.url)]]);

Unfortunately, this is not establishing the file path in the .js file.

The full .js is;

// https://observablehq.com/@d3/collapsible-tree@360
export default function define(runtime, observer) {
  const main = runtime.module();
  const fileAttachments = new Map([["flare-2.json",new URL("../files/paul",import.meta.url)]]);
  main.builtin("FileAttachment", runtime.fileAttachments(name => fileAttachments.get(name)));
  main.variable(observer()).define(["md"], function(md){return(
md`# Collapsible Tree

Click a black node to expand or collapse [the tree](/@d3/tidy-tree).`
)});
  main.variable(observer("chart")).define("chart", ["d3","data","dy","margin","width","dx","tree","diagonal"], function(d3,data,dy,margin,width,dx,tree,diagonal)
{
    
    
  const root = d3.hierarchy(data);

  root.x0 = dy / 2;
  root.y0 = 0;
  root.descendants().forEach((d, i) => {
    d.id = i;
    d._children = d.children;
    if (d.depth && d.data.name.length !== 7) d.children = null;
  });

  const svg = d3.create("svg")
      .attr("viewBox", [-margin.left, -margin.top, width, dx])
      .style("overflow", "visible")
      .style("width", "100vw")
      .style("font", "1em Arial")
      .style("fill", "#383838")
      .style("padding-left", 0)
      .style("padding-top", 0)
      .style("margin-top", "5vh")
      .style("margin-left", "5vw")
      .style("top", 280)
      .style("user-select", "none");

  const gLink = svg.append("g")
      .attr("fill", "none")
      .attr("stroke", "#555")
      .attr("stroke-opacity", 0.4)
      .attr("stroke-width", 1.2);

  const gNode = svg.append("g")
      .attr("cursor", "pointer")
      .attr("pointer-events", "all");
      
  function update(source) {
    const duration = d3.event && d3.event.altKey ? 2500 : 250;
    const nodes = root.descendants().reverse();
    const links = root.links();

    // Compute the new tree layout.
    tree(root);

    let left = root;
    let right = root;
    root.eachBefore(node => {
      if (node.x < left.x) left = node;
      if (node.x > right.x) right = node;
    });

    const height = right.x - left.x + margin.top + margin.bottom;

    const transition = svg.transition()
        .duration(duration)
        .attr("viewBox", [-margin.left, left.x - margin.top, width, height])
        .tween("resize", window.ResizeObserver ? null : () => () => svg.dispatch("toggle"));

    // Update the nodes…
    const node = gNode.selectAll("g")
      .data(nodes, d => d.id);
      

    // Enter any new nodes at the parent's previous position.
    const nodeEnter = node.enter().append("g")
        .attr("transform", d => `translate(${source.y0},${source.x0})`)
        .attr("fill-opacity", 0)
        .attr("stroke-opacity", 0)
        .on("click", (event, d) => {
          d.children = d.children ? null : d._children;
          update(d);
        });

    nodeEnter.append("circle")
        .attr("r", 6)
        .attr("fill", d => d._children ? "#79ec79" : "#B0B0B0")
        .attr("stroke-width", 10);

    nodeEnter.append("text")
        .attr("dy", "0.31em")
        .attr("x", d => d._children ? -16 : 16)
        .attr("text-anchor", d => d._children ? "end" : "start")

        .text(d => d.data.name)
      .clone(true).lower()
        .attr("stroke-linejoin", "round")
        .attr("stroke-width", 3)
        .attr("stroke", "white");
        
        
    // Transition nodes to their new position.
    const nodeUpdate = node.merge(nodeEnter).transition(transition)
        .attr("transform", d => `translate(${d.y},${d.x})`)
        .attr("fill-opacity", 1)
        .attr("stroke-opacity", 1);

    // Transition exiting nodes to the parent's new position.
    const nodeExit = node.exit().transition(transition).remove()
        .attr("transform", d => `translate(${source.y},${source.x})`)
        .attr("fill-opacity", 0)
        .attr("stroke-opacity", 0);

    // Update the links…
    const link = gLink.selectAll("path")
      .data(links, d => d.target.id);

    // Enter any new links at the parent's previous position.
    const linkEnter = link.enter().append("path")
        .attr("d", d => {
          const o = {x: source.x0, y: source.y0};
          return diagonal({source: o, target: o});
        });

    // Transition links to their new position.
    link.merge(linkEnter).transition(transition)
        .attr("d", diagonal);

    // Transition exiting nodes to the parent's new position.
    link.exit().transition(transition).remove()
        .attr("d", d => {
          const o = {x: source.x, y: source.y};
          return diagonal({source: o, target: o});
        });

    // Stash the old positions for transition.
    root.eachBefore(d => {
      d.x0 = d.x;
      d.y0 = d.y;
    });
  }

  update(root);

  return svg.node();
}
);
  main.variable(observer("diagonal")).define("diagonal", ["d3"], function(d3){return(
d3.linkHorizontal().x(d => d.y).y(d => d.x)
)});
  main.variable(observer("tree")).define("tree", ["d3","dx","dy"], function(d3,dx,dy){return(
d3.tree().nodeSize([dx, dy])
)});
  main.variable(observer("data")).define("data", ["FileAttachment"], function(FileAttachment){return(
FileAttachment("flare-2.json").json()
)});
  main.variable(observer("dx")).define("dx", function(){return(
30
)});
  main.variable(observer("dy")).define("dy", ["width"], function(width){return(
width / 4
)});
  main.variable(observer("margin")).define("margin", function(){return(
{top: 10, right: 120, bottom: 10, left: 40}
)});
  main.variable(observer("d3")).define("d3", ["require"], function(require){return(
require("d3@6")
)});
  return main;
}

Stefino76 · Accepted Answer · 2022-10-03 09:28:59Z

1

You can try to move your session_start() at the very beginning of the file. Then, in the script, using only $file_path variable. Like this:

<?php 
session_start();
$file_path = $_SESSION['file_path'];
?>
...
const fileAttachments = new Map([["flare-2.json",new URL("<?=$file_path?>", import.meta.url)]]);

answered Oct 3, 2022 at 9:28

Stefino76

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2 Comments

hugh23 Over a year ago

That would seem like a good idea, but doing this corrupts the .js file.

Stefino76 Over a year ago

Ok, you can't use php inside a .js file. I think the best solution for you is to create a new file php that return the $file_path variable. You can fetch it inside your .js file and then use it inside the function

Lennard K · Accepted Answer · 2022-10-03 11:56:13Z

1

You can include a variable with you're script tag like:

<?php
  session_start();
  $file_path = $_SESSION['file_path'];
?>

<script src="{url to folder}" file-path="<?php echo $file_path;?>"></script>

And inside the js file put the following on top:

const filePath = document.currentScript.getAttribute('file-path');

Now you have a variable with the value inside you're js file so you can put it inside the fileAttachments variable like:

const fileAttachments = new Map([["flare-2.json",new URL(filePath ,import.meta.url)]]);

answered Oct 3, 2022 at 11:56

Lennard K

521 silver badge5 bronze badges

1 Comment

hugh23 Over a year ago

Somehow any modification to the .js file causes it to stop working. Just adding the const filePath variable stopped it working. I changed the privileges on the file but this didn't help either

hugh23 · Accepted Answer · 2022-10-08 22:11:18Z

0

The solution is;

Create a session variable in php;

$file_path = "../files/$user";
$_SESSION['file_path'] = $file_path;

Declare a script in the html head declaring a javascript global variable;

   <script> 
       var filePath ="<?php session_start(); echo $_SESSION['file_path'];?>"
   </script>

edited Oct 8, 2022 at 22:11

answered Oct 8, 2022 at 21:48

hugh23

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