CODEWITHSUNDEEP
mysqljsonnode.js
Ckappo
Ckappo

Reputation: 597

Nodejs loop through mysql Query give result = undefined

i have a Json Object and want to loop thorugh it. In my loop I want to execute a select query and save it result to another json Array.

So I start with a loop, performe a mysql query and want just log the results:

for (var x = 0; x < obj.length; x++) {
     var query = connection.query('SELECT Id, date FROM tbl1 WHERE Id LIKE '+ mysql.escape(obj[x].ident) +'; SELECT Id, date FROM tbl WHERE Id LIKE '+ mysql.escape(obj[x].ident) +' ORDER BY date DESC Limit 1 offset 1', function (error, results, fields) {
            if (error) {throw error;}
            if (!error) {
                console.log("resultset"+results); //<- Here I get the right result
                console.log("ID: "+results[0].Id); //<- UNDEFINED
                console.log("ID-LAST-entry: "+ results[1].Id); //<- UNDEFINED
                          } });

The Problem is that for booth results (0 and 1) i get = UNDEFINED.

Where is my mistake?

Upvotes: 0

Views: 899

Answers (1)

Master Po
Master Po

Reputation: 1697

From the value of results, You can see that it is NOT an array of objects instead it is an array of arrays where each item is an object. You need to iterate inner array to get the Id. See the snippet below. Parsing the result into JSON and then reads the required data. 

if (!error) {

    var parsedResults = JSON.parse(JSON.stringify(results));
    var outerArraySize = parsedResults.length;

    for (var outerIndex = 0; outerIndex < outerArraySize; ++outerIndex) {
        var innerArraySize = parsedResults[outerIndex].length;
        for (var innerIndex = 0; innerIndex < innerArraySize; ++innerIndex)
            console.log("ID: " + parsedResults[outerIndex][innerIndex].Id);
    }
}

Upvotes: 1

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