Question

I’ve got the following JSON structure that defines a table and it’s data.

var arrTable = 
  [{"table": "tblConfig",
  "def":
    [{"column": "Property", "type": "TEXT NOT NULL"},
     {"column": "Value",    "type": "TEXT NOT NULL"}],
  "data":
    [{"Property": "VersionNumber", "Value": "1.0"},
     {"Property": "ReleaseDate",   "Value": "2010-01-01"}]
  }]

The code describes a table named “tblConfig” with two columns, “Property” and “Value” both are type “TEXT NOT NULL”. The table has two rows of data.

Property_______Value_____
VersionNumber  1.0
ReleaseDate    2010-01-01

Below is my Javascript code to create and populate the table. It builds the create table SQL great but I’m having trouble with the populate function.

dbController.updateDatabase = function () {
  this.db.transaction(function (transaction) {
//load data.json
    var dbDefs = dbController.jsonObject(url + "data.json")
//parse array "table"
    eval(dbDefs);
    for (var i in arrTables) {
      createTable(arrTables[i].table, arrTables[i].def, arrTables[i].data);
    }
//create table
    function createTable(table, arrDef, arrData) {
      var arrColumns = [];
      var strSQL = "CREATE TABLE " + table + " (";
      for (var j in arrDef) {
        arrColumns.push(arrDef[j].column);
        strSQL += arrDef[j].column + " " + arrDef[j].type + ", ";
      }
      strSQL = strSQL.substring(0, strSQL.lastIndexOf(",")) + ")";
      transaction.executeSql(strSQL, [],
        function () {
          console.log(table + " created.");
          populateTable(table, arrData);
          return;
        },
        dbController.errorHandler
      );
    }
//populate table
    function populateTable(table, arrData) {
      ...
    }
  });
};

I want to be able to get the column names (“Property” & “Value”) out of the “data” object and use them in the insert SQL string. I thought something like this would work.

//populate table
    function populateTable(table, arrColumns, arrData) {
      var strVal;
      var arrVal;
      for (var k in arrData) {
        strVal = "?,";
        arrVal.push(arrData[k]. ~~ KEY VALUE NAME ~~ )
      }
      var strSQL = "INSERT INTO " + table + " (" + strCol + ") ";
      strSQL += "VALUES (" + strVal.lastIndexOf(",") + ");";
      transaction.executeSql(strSQL, arrVal, null, dbController.errorHandler);
      console.log("  " + table + " populated.");
    }

The bugger is the bolded statement. I’ve tried using .hasOwnProperty() on arrData but that only returns 0 and 1, not the words “Property” and “Value”. I don’t want to use the “arrData[k].Property” notation because there are many more tables in the schema and I don’t want to write create and insert statements for each table.

Any help is greatly appreciated.

---

Thanks to everyone for their help and head-scratching due to my late-night post. My intention with this function was to have a JSON object that defined multiple tables and held the table’s data. Since none of the tables have the same number of columns or column names I had to devise a way of getting the data out of “data” without using the object.member syntax. I had forgotten about the object["member"] syntax.
Here’s the solution.

dbController.updateDatabase = function (a) {
  this.db.transaction(function (transaction) {
//load data.json
    var dbDefs = dbController.jsonObject(dbController.dbFolder + "data.json")

//parse array "table"
    eval(dbDefs);
    for(var i in arrTables) {
      createTable(arrTables[i].table, arrTables[i].def, arrTables[i].data);
    }

//create table
    function createTable(table, arrDef, arrData){
      var arrColumns = [];
      var strSQL = "Create Table " + table + " (";
      for(var j in arrDef) {
        arrColumns.push(arrDef[j].column);
        strSQL += arrDef[j].column + " " + arrDef[j].type + ", ";
      }
      strSQL = strSQL.substring(0, strSQL.lastIndexOf(",")) + ")";
      transaction.executeSql(strSQL, [],
        function() {
          console.log(table + " created.");
          populateTable(table, arrColumns, arrData);
          return;
        },
        dbController.errorHandler
      );
    }

//populate table
    function populateTable(table, arrColumns, arrData) {
      for (var k in arrData) {
        var arrVal = [];
        var strVal = "";
        for (var l = 0; l < arrColumns.length; l++) {
          strVal += "?,";
          arrVal.push(arrData[k][arrColumns[l]])
        }
        var strSQL = "Insert Into "+table+" (" + arrColumns.toString()+") ";
        strSQL += "Values ("+strVal.substring(0, strVal.lastIndexOf(","))+");";
        transaction.executeSql(strSQL, arrVal, null, dbController.errorHandler);
      }
      console.log("  " + table + " populated.");
    }
  });
};

Answer 1

I’m making some assumptions here, but try changing:

for (var k in arrData) {
    strVal = "?,";
    arrVal.push(arrData[k]. ~~ KEY VALUE NAME ~~ )
}
var strSQL = "INSERT INTO " + table + " (" + strCol + ") ";
strSQL += "VALUES (" + strVal.lastIndexOf(",") + ");";

to:

for (var i =0; i < arrColumns.length; ++i) strVal += ',?';
for (var k in arrData)
{
    arrVal[k] = [];
    for (var i in arrColumns) 
        arrVal[k].push (arrData[k][arrColumns[i]]);
}
var strSQL = "INSERT INTO " + table + " (" + strCol + ") ";
strSQL += "VALUES (" + strVal.substr(1) + ");";

If I’m correct in thinking that transaction.executeSql(strSQL, arrVal, null, dbController.errorHandler); accepts multiple records, then this should work fine. Otherwise, call

transaction.executeSql(strSQL, arrVal[0], null, dbController.errorHandler);

instead