What steps can be taken to resolve the error message: JSON.parse: unexpected end of data at line 1 column 1 of the JSON data?

Question

What steps can be taken to resolve the error message: JSON.parse: unexpected end of data at line 1 column 1 of the JSON data?

I'm facing an issue while trying to retrieve data for my map using an AJAX call. The error message I receive is:

SyntaxError: JSON.parse: unexpected end of data at line 1 column 1 of the JSON data

. Interestingly, two previous datasets in my application worked fine and were displayed on the screen. However, when I attempted to add a third dataset, this error occurred and the variable dataArray remains empty.

geojson_popupInfo = {
    "type": "FeatureCollection",
    "features": [],
};

geojson_dataTable = {
    "type": "FeatureCollection",
    "features": [],
};

var dataArray = data.split(", ;");
dataArray.pop();

dataArray.forEach(function(d){
d = d.split(", "); 

var feature_popupInfo = {
    "type": "Feature",
    "properties": {}, 
    "geometry": JSON.parse(d[fieldList.length]) 
};

var feature_dataTable = {
    "type": "Feature",
    "properties": {}, 
    "geometry": JSON.parse(d[fieldList.length]) 
};

for (var i=0; i<fieldList.length; i++){
    if ([fieldList[i].show_field] == 't') {
        feature_popupInfo.properties[fieldList[i].field_alias] = d[i];
    }
    feature_dataTable.properties[fieldList[i].field_name] = d[i]; 
};
geojson_popupInfo.features.push(feature_popupInfo);
geojson_dataTable.features.push(feature_dataTable);
});
console.log(dataArray)

javascript json leaflet

Answer 1

Answer №1

Ensure that your PHP script is strictly outputting JSON data. At the moment, you are currently:

echo $attr.", ";

Later on, you have:

echo json_encode($attribute_names);

This means your output includes both comma-separated text:

2, 1, 0, 0, 0, , 0, 0, [snip], 0, 1840, 0, 2,

as well as valid GeoJSON:

{"type":"MultiPolygon","coordinates":[[[[6.74578464881977, [snip] ,53.3291017450563]]]]}

Only return GeoJSON with a single echo, and avoid any other unnecessary echo calls to resolve this issue.

Answer 2

Ensure that your PHP script is strictly outputting JSON data. At the moment, you are currently:

echo $attr.", ";

Later on, you have:

echo json_encode($attribute_names);

This means your output includes both comma-separated text:

2, 1, 0, 0, 0, , 0, 0, [snip], 0, 1840, 0, 2,

as well as valid GeoJSON:

{"type":"MultiPolygon","coordinates":[[[[6.74578464881977, [snip] ,53.3291017450563]]]]}

Only return GeoJSON with a single echo, and avoid any other unnecessary echo calls to resolve this issue.

Answer 3

Answer №2

It looks like the issue here is that the output from your script contains a combination of JSON and non-JSON data, resulting in portions of the JSON being split up when processed by JavaScript. This causes your array d to no longer be valid JSON.

In most cases, returning pure JSON would be ideal. However, due to the JSON data within the table, achieving this can be challenging.

There are a couple of approaches you could take:

Decode the JSON data when extracting it from the table, convert it into an array of objects, re-encode the entire array as JSON, and then return it.
Alternatively, instead of using commas and semicolons to separate your data, consider using unique characters or strings like '|' or 'XYZ' that have no significance in JSON and aren't present in the database values.

Answer 4

It looks like the issue here is that the output from your script contains a combination of JSON and non-JSON data, resulting in portions of the JSON being split up when processed by JavaScript. This causes your array d to no longer be valid JSON.

In most cases, returning pure JSON would be ideal. However, due to the JSON data within the table, achieving this can be challenging.

There are a couple of approaches you could take:

Decode the JSON data when extracting it from the table, convert it into an array of objects, re-encode the entire array as JSON, and then return it.
Alternatively, instead of using commas and semicolons to separate your data, consider using unique characters or strings like '|' or 'XYZ' that have no significance in JSON and aren't present in the database values.

What steps can be taken to resolve the error message: JSON.parse: unexpected end of data at line 1 column 1 of the JSON data?

Answer №1

Answer №2

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