Transferring string information from C# to JavaScript

Question

Transferring string information from C# to JavaScript

After successfully resolving an issue on my localhost following this particular problem, I encountered difficulties when attempting to integrate the map into our web application.

EDIT: The javascript array appears empty in the source code of the rendered page (indicating that the markers1 / markers2 strings are also empty).

Continuing from a previous inquiry:

I am aiming to showcase a map populated with an array of markers using OSM and the OpenLayers Library. While static values function without issues, the challenge arises when trying to display SQL table-based markers. What is the optimal method for extracting data and populating it within the JS array?

Below is the provided code snippet:

inclined towards reaching

In addition to my code, here is the markup containing the necessary JavaScript to render the map:

<%@ Page Title="" Language="C#" MasterPageFile="~/MasterPage.master" AutoEventWireup="false" CodeFile="fibre.aspx.cs" Inherits="fibre" %>

<asp:Content ID="cntChart" ContentPlaceHolderID="CPH_visual1" Runat="Server">
    <asp:Literal  ID="Literalsingle" runat="server"></asp:Literal>
    <div id="mapdiv" style="height: 100%; position: relative;">
       <!-- map will render here! -->
    </div>

    <!-- map built with OpenLayers api on OpenStreetMap -->
    <script src="http://www.openlayers.org/api/OpenLayers.js"></script>
    <script>
        // JS script content goes here
    </script>
</asp:Content>

Any insights on why this setup might be failing? Your assistance is much appreciated!

javascript c#asp.net openlayers

Answer 1

Answer №1

Perhaps this information could be beneficial to you:

In order for the javascript array format to work correctly, it should be structured as

[[lat, lon], [lat, lon], [lat, lon]]

. However, in your current code, the format appears as [lat, long], [lat, long],, with an extra comma at the end and missing square brackets [].

You can try using the following code snippet:

        while (rst2.Read())
        {
            // Build the marker data
            markerStr2.AppendFormat("[{0}, {1}], ", rst2["lat"].ToString(), rst2["lon"].ToString());
        }

        //SAMPLE CODE
        string sampleFormat = markerStr2.ToString();
        if (sampleFormat.EndsWith(","))
        {
             sampleFormat = sampleFormat.Substring(0, sampleFormat.Length - 2);
        }
        sampleFormat  = string.Format("[{0}]", sampleFormat);

        // Close the result set Reader object
        rst2.Close();

Then, in the javascript section, utilize the sampleFormat variable to load in markers1.

  var markers1 = [ <%=sampleFormat%>];

Repeat the same process for markers2.

If possible, please provide more details regarding the error you are encountering.

I apologize for any language barriers, but I hope this information proves helpful to you.

Answer 2

Perhaps this information could be beneficial to you:

In order for the javascript array format to work correctly, it should be structured as

[[lat, lon], [lat, lon], [lat, lon]]

. However, in your current code, the format appears as [lat, long], [lat, long],, with an extra comma at the end and missing square brackets [].

You can try using the following code snippet:

        while (rst2.Read())
        {
            // Build the marker data
            markerStr2.AppendFormat("[{0}, {1}], ", rst2["lat"].ToString(), rst2["lon"].ToString());
        }

        //SAMPLE CODE
        string sampleFormat = markerStr2.ToString();
        if (sampleFormat.EndsWith(","))
        {
             sampleFormat = sampleFormat.Substring(0, sampleFormat.Length - 2);
        }
        sampleFormat  = string.Format("[{0}]", sampleFormat);

        // Close the result set Reader object
        rst2.Close();

Then, in the javascript section, utilize the sampleFormat variable to load in markers1.

  var markers1 = [ <%=sampleFormat%>];

Repeat the same process for markers2.

If possible, please provide more details regarding the error you are encountering.

I apologize for any language barriers, but I hope this information proves helpful to you.

Answer 3

Answer №2

The problem lies in your failure to convert markers1 and markers2 into a format that can be understood by JavaScript.

Give this a try:

var markers1AsString = '[ <%=markers1%>]';
var markers2AsString = '[ <%=markers2%>]';

Make sure to include the quotation marks around the [].

Then, simply parse the strings into JSON arrays like so:

var markers1 = JSON.parse(markers1AsString);
var markers2 = JSON.parse(markers2AsString);

for (var i = 0; i < markers2.length; i++) {
  // do something
}

Answer 4

The problem lies in your failure to convert markers1 and markers2 into a format that can be understood by JavaScript.

Give this a try:

var markers1AsString = '[ <%=markers1%>]';
var markers2AsString = '[ <%=markers2%>]';

Make sure to include the quotation marks around the [].

Then, simply parse the strings into JSON arrays like so:

var markers1 = JSON.parse(markers1AsString);
var markers2 = JSON.parse(markers2AsString);

for (var i = 0; i < markers2.length; i++) {
  // do something
}

Transferring string information from C# to JavaScript

Answer №1

Answer №2

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