Need help Modifing Json Export/import script to filter null values

Help...
I am using Michael N.'s Scrypt from https://app.roll20.net/forum/post/1755413/imports-...
and have been attempting to rewrite a section of it to remove all null values exported from sheets in the below section of code but I keep going in circles.

function exportAttributes( charID ){
    var attributes = findObjs({_type: "attribute", _characterid: charID}); 
    var exported = [];
    for(var i in attributes)
    {
        a = attributes[i];
        exported.push({ 
            "name": a.get("name"),
            "current": a.get("current"),
            "max": a.get("max")
        });
    }
    return exported;
}

// My knowledge in Javascript is limited to what I learned in high school many years ago.
but what I am looking for is if the json created would contain this:

{
    "name": "Generic_Attribute1",
    "current": "42 is the Answer to the Ultimate Question of Life, the Universe, and Everything",
},
{
    "name": "Generic_Attribute2",
    "max": "11d7+33"
},

instead of this

{
    "name": "Generic_Attribute1",
    "current": "42 is the Answer to the Ultimate Question of Life, the Universe, and Everything",
    "max": ""
},
{
    "name": "Generic_Attribute2",
    "current": "",
    "max": "11d7+33"
},
{
    "name": "Generic_Attribute3",
    "current": "",
    "max": ""
},

//even if "name": "Generic_Attribute3", could not be removed it would make things better for me

Try this

function exportAttributes(charID) {
  "use strict";
  return findObjs({
    _type: "attribute",
    _characterid: charID
  }).reduce((m, attr) => {
    // _.omit filters an object by property values - in this case, it filters out properties
    // whose values are empty strings
    const data = _.omit({
      current: attr.get('current'),
      max: attr.get('max'),
      name: attr.get('name'),
    }, x => x === '');

    // Only include an attribute in the final data set if the name is nonempty and either
    // current or max are present
    if ('name' in data && ('current' in data || 'max' in data)) m.push(data);
    return m;
  }, []);
}

Something like this:

function exportAttributes( charID ){
    var attributes = findObjs({_type: "attribute", _characterid: charID});
    var exported = [];
    for(var i in attributes)
    {
        a = attributes[i];
        let o = {},
        let p = ['name','current','max'];
        _.each(p, (k)=>{
            let v = a.get(p);
            if(v.length){
                o[p]=v;
            }
        });
        
        exported.push(o);
    }
    return exported;
}

error:

TypeError: Cannot read property 'push' of undefined TypeError: Cannot read property 'push' of undefined at findObjs.reduce (apiscript.js:148:66) at Array.reduce (native) at exportAttributes (apiscript.js:137:6) at exportChar (apiscript.js:97:25) at exportAll (apiscript.js:55:7) at apiscript.js:43:3 at eval (eval at (/home/node/d20-api-server/api.js:146:1), :65:16) at Object.publish (eval at (/home/node/d20-api-server/api.js:146:1), :70:8) at checkForReady (/home/node/d20-api-server/api.js:1314:12) at /home/node/d20-api-server/api.js:1394:9

The Arron this is the error I got with your edit:
For reference, the error message generated was: SyntaxError: let is disallowed as a lexically bound name
 

E. ManWhoLaughs said:

error:

TypeError: Cannot read property 'push' of undefined TypeError: Cannot read property 'push' of undefined at findObjs.reduce (apiscript.js:148:66) at Array.reduce (native) at exportAttributes (apiscript.js:137:6) at exportChar (apiscript.js:97:25) at exportAll (apiscript.js:55:7) at apiscript.js:43:3 at eval (eval at (/home/node/d20-api-server/api.js:146:1), :65:16) at Object.publish (eval at (/home/node/d20-api-server/api.js:146:1), :70:8) at checkForReady (/home/node/d20-api-server/api.js:1314:12) at /home/node/d20-api-server/api.js:1394:9

Ooops, forgot a line. Try again.

that worked jakob thanks 

I've been playing with it and is it possible to modify the .omit to include other values: I'm interested in "0" and 0.
I've been reading on it but I cant seem to grasp it with my limited knowledge.

E. ManWhoLaughs said:

I've been playing with it and is it possible to modify the .omit to include other values: I'm interested in "0" and 0.
I've been reading on it but I cant seem to grasp it with my limited knowledge.

Absolutely. You want to modify this line:

}, x => x === '');

and replace the boolean expression x === '' by something else. For example, to also exclude 0 (I'm not exactly sure if attribute values are ever integers, though, they should normally be strings):

}, x => (x === '' || x === 0));

To explain what's happening: the second argument of  _.omit,  x => x === '', is a function that sends x to the value of the expression x === '' (so either true or false), and _.omit omits properties where the value of the property makes this expression true. So by substituting another expression, namely (x === '' || x === 0), we change the conditions under which this evaluates to true.

Adding "0" is an exercise :).

a million thanks I knew what expressions I need just not how I formated them into the function (Json size is reduced by almost 50% now)

E. ManWhoLaughs said:

The Arron this is the error I got with your edit:
For reference, the error message generated was: SyntaxError: let is disallowed as a lexically bound name
 

Ah.. had a , instead of a ; at the end of the first let definition. =D  Glad to see you got it working though.