Fix "error: Value in [posts.slug] exceeds maximum length of 150 characters." error when importing from Wordpress to Ghost

slugline_shortner.js

var fs = require('fs');
var filePath = process.argv[2];

var content = null;

fs.readFile(filePath, 'utf8', function (err, data) {
    if (err) {
        console.log('Error: ' + err);
        return;
    }

    //Sometimes the shortning causes duplicte sluglines, which are forbidden. So the map is here to handle it.
    var slugsMap = {};

    content = JSON.parse(data);
    var posts = content.data.posts;
    posts.forEach(function (post) {
        if (post.slug.length > 150) {
            post.slug = post.slug.substring(0, 149);

            if (slugsMap[post.slug]) {
                console.log("Found duplicate: " + post.slug);
                slugsMap[post.slug]++
                post.slug = (slugsMap[post.slug] + post.slug).substring(0, 149);
                console.log("Changed to: " + post.slug);
            } else {
                slugsMap[post.slug] = 1;
            }
        }
    });

    var outputFile = "./parsed_slugline.json";
    fs.writeFile(outputFile, JSON.stringify(content), function (err) {
        if (err) {
            console.log(err);
        } else {
            console.log("File was saved to " + __dirname + "/" + outputFile);
        }
    })
});

Run the script on the json file you exported from wordpress, and use the new output when importing to Ghost.