SQLite to JSON in a simple JS function - parsing JSON - json

Question

I want to transform a SQLite Database into a JSON object. After searching the web I decided to write a function by myself. I'm still a beginner in JS/JSON/jQuery and I thought the following code should work:
function sqlite2json(){
newJson = '{ "$resources": [';
offlinedb = openDatabase (shortName, version, displayName, maxSize);
offlinedb.transaction(function(transaction) {
transaction.executeSql('SELECT * FROM Zaehlliste;', [],
function(transaction, result) {
if (result != null && result.rows != null) {
for (var k = 0; k < result.rows.length; k++) {
var row = result.rows.item(k);
newJson += '{ "Field0":"' + row.Field0 + '", "Field1":"' + row.Field1 + '", "Field2":"' + row.Field2 + '", "Field3":"' + row.Field3 + '", "Field4":"' + row.Field4 + '", "Field5":"' + row.Field5 + '"},'
}
jsonall = newJson + ']}';
alert(jsonall); //shows me a correct JSON as string
jsonobjoff = $.parseJSON(jsonall);
for (i = 0; i < jsonobjoff.$resources.length; i++) {
$('#json').append("<li>" + jsonobjoff.$resources[i].Field0 + " " + jsonobjoff.$resources[i].Field1 + " " + jsonobjoff.$resources[i].Field2 + " " + jsonobjoff.$resources[i].Field3 + " " + jsonobjoff.$resources[i].Field4 + " " + jsonobjoff.$resources[i].Field5 + "</li>");
}
}
},errorHandler);
},errorHandler, nullHandler);
}
This second for-loop and putting content into that element with its id="json" is just to control, that I finally got a true JSON object, but unfortunately there is no list appearing. The alert after declaring jsonall shows me a correct JSON-Object as a string. I think that parseJSON is not working, but I have no clue, why it is not working. Could it be that comma after the last entry of the JSON-Object? I know this is not clean, but it should still work...?

Answer 1

the json you generate is incorrect.
you add a trailing comma after every object (in your first for loop), but the last entry shouldn't add a comma, or it isnt valid json.
change this:
newJson += '{ "Field0":"' + row.Field0 + '", "Field1":"' + row.Field1 + '", "Field2":"' + row.Field2 + '", "Field3":"' + row.Field3 + '", "Field4":"' + row.Field4 + '", "Field5":"' + row.Field5 + '"},';
to:
if(k > 0) newJson += ',';
newJson += '{ "Field0":"' + row.Field0 + '", "Field1":"' + row.Field1 + '", "Field2":"' + row.Field2 + '", "Field3":"' + row.Field3 + '", "Field4":"' + row.Field4 + '", "Field5":"' + row.Field5 + '"}';
that will work (if you dont have special characters in your strings)
i would recommend that you use this json encoder instead of manually generating the string, it will handle special characters too, which yours will have problems with: https://github.com/douglascrockford/JSON-js/blob/master/json2.js
code for this:
change newJson = '{ "$resources": ['; to newJson = { $resources: [] };
and in the loop:
newJson.$resources[k] = { Field0: row.Field0, Field1: row.Field1, Field2: row.Field2, Field3: row.Field3, Field4: row.Field4, Field5: row.Field5 };
you could just use newJson.$resources[k] = row; here, but if row has more Fields that you dont want to show, they will be taken too
create the json string:
jsonall = JSON.stringify(newJson);