Dynamic merge of JSON files in Gruntfile.js

Question

In my gruntfile.js I'm using this plugin `grunt.loadNpmTasks('grunt-json-merge'); and I'm trying to merge two JSON files using this code:

    json_merge: {
        files: {
            files: { 'dest/resources/locales/merged.json':
                function () {
                    var includedScripts = [];
                                    includedScripts.push(project_x+'/locales/locale-fr.json');
                                    includedScripts.push(project_y+'/locales/locale-fr.json');
                    return includedScripts;

}
            },
        },
    }

I get Warning: pattern.indexOf is not a function Use --force to continue.

NB: I need to use a function to define the input values as it contains some variables and maybe I will need to integrate a for loop later.

The used library is this one https://github.com/ramiel/grunt-json-merge

Answer 1

The problem is that the value of an entry in the files object should be an array, but because you haven't called the function, only declared it, the value is a function.

This should work:

json_merge: {
    files: {
        files: { 'dest/resources/locales/merged.json':
            (function () {
                var includedScripts = [];
                includedScripts.push(project_x+'/locales/locale-fr.json');
                includedScripts.push(project_y+'/locales/locale-fr.json');
                return includedScripts;
            })() // call the function here to return the array
        },
    }
}

But you might also find it more comfortable to extract the function, give it a name, and then invoke it by name in the task:

function getJSONFilesToMerge () {
    var includedScripts = [];
    includedScripts.push(project_x+'/locales/locale-fr.json');
    includedScripts.push(project_y+'/locales/locale-fr.json');
    return includedScripts;
}

// .....

json_merge: {
    files: {
        files: { 
            'dest/resources/locales/merged.json': getJSONFilesToMerge()
        },
    }
}