Send arguments to a callback function within an Elasticsearch JavaScript API search query

Question

Send arguments to a callback function within an Elasticsearch JavaScript API search query

I have a function that requires an aggregation for each word entered by the user and then generates a chart.

I am wondering how I can access the value of the variable i from my loop in the callback when the request is made.

Is there a way to include the variable i in the predefined parameters set by the elasticsearch API?

for(var i = 0; i < 15; i++)
{
    client.search({
        index: 'twitter',
        type: "status",
        size : 10,
        body: 
        {
            query: {
                "bool": {
                    "must": [
                        {"query_string": {
                            "fields" : ["text"],
                            "default_operator" : "AND",
                            "query" : $scope.motsCompares[i]
                        }},
                        {"range": {
                            "created_at": {
                                "gte": moment().subtract(duration, key).format("YYYY-MM-DD")
                            }
                        }}
                    ]
                }
            },
            aggs : {
                "frequence_mots" : {
                    "date_histogram" : {
                        "field" : "created_at",
                        "interval" : "day",
                        "format" : "dd/MM/yyyy",
                        "min_doc_count" : 0
                    }
                }
            }
        }
    }).then(function traiterResultat(body) {

        // Here's where I want to refer to the current i value from the loop to access the right word in my array ($scope.motsCompares[i])

    }, function (error) {
            console.trace(error.message);
    });
}

javascript callback elasticsearch promise

Answer 1

Answer №1

Back in the day, without the convenience of fn.bind(), developers had to resort to closures or other less-than-ideal methods that shall remain unnamed.

But fear not! Thanks to ECMAScript 5, we now have the power of "currying" with fn.bind(). This allows us to pass i upfront and body later on when our promise chain is ready to unleash its success sequence.

for(var i = 0; i < 15; i++) {
    (function(i) {
        client.search({
            // ...
        }).then(function (i, body) {
            // The callback function inside .then() is actually an intermediary function created by .bind().
            // Here, `i` corresponds to the loop's `i` value bound-in using .bind().
            // The actual value for `body` will be supplied to this intermediary function once the promise completes successfully.
        }.bind(null, i), function (error) {
            console.trace(error.message);
        });
    })(i);
}

And don't forget, you can always replace null within .bind(null, i) with any object that you want to serve as the context for the callback function.

Answer 2

Back in the day, without the convenience of fn.bind(), developers had to resort to closures or other less-than-ideal methods that shall remain unnamed.

But fear not! Thanks to ECMAScript 5, we now have the power of "currying" with fn.bind(). This allows us to pass i upfront and body later on when our promise chain is ready to unleash its success sequence.

for(var i = 0; i < 15; i++) {
    (function(i) {
        client.search({
            // ...
        }).then(function (i, body) {
            // The callback function inside .then() is actually an intermediary function created by .bind().
            // Here, `i` corresponds to the loop's `i` value bound-in using .bind().
            // The actual value for `body` will be supplied to this intermediary function once the promise completes successfully.
        }.bind(null, i), function (error) {
            console.trace(error.message);
        });
    })(i);
}

And don't forget, you can always replace null within .bind(null, i) with any object that you want to serve as the context for the callback function.

Answer 3

Answer №2

Implement a different approach for your callback:

for(var j = 0; j < 15; j++)
{
  client.search({
                  index: 'twitter',
                  type: "status",
                  size : 10,
                  body:
                  {
                    query: {
                      "bool": {
                        "must": [
                          {"query_string": {
                            "fields" : ["text"],
                            "default_operator" : "AND",
                            "query" : $scope.motsCompares[j]
                          }},
                          {"range": {
                            "created_at": {
                              "gte": moment().subtract(duration, key).format("YYYY-MM-DD")
                            }
                          }}
                        ]
                      }
                    },
                    aggs : {
                      "frequence_mots" : {
                        "date_histogram" : {
                          "field" : "created_at",
                          "interval" : "day",
                          "format" : "dd/MM/yyyy",
                          "min_doc_count" : 0
                        }
                      }
                    }
                  }
                }).then(createCustomCallback(j), function (error) {
                          console.trace(error.message);
                        });
}

function createCustomCallback(j){
  return function processResult(body) {

    // utilize j from the loop here to access the correct word in my array ($scope.motsCompares[j])

  }
}

Answer 4

Implement a different approach for your callback:

for(var j = 0; j < 15; j++)
{
  client.search({
                  index: 'twitter',
                  type: "status",
                  size : 10,
                  body:
                  {
                    query: {
                      "bool": {
                        "must": [
                          {"query_string": {
                            "fields" : ["text"],
                            "default_operator" : "AND",
                            "query" : $scope.motsCompares[j]
                          }},
                          {"range": {
                            "created_at": {
                              "gte": moment().subtract(duration, key).format("YYYY-MM-DD")
                            }
                          }}
                        ]
                      }
                    },
                    aggs : {
                      "frequence_mots" : {
                        "date_histogram" : {
                          "field" : "created_at",
                          "interval" : "day",
                          "format" : "dd/MM/yyyy",
                          "min_doc_count" : 0
                        }
                      }
                    }
                  }
                }).then(createCustomCallback(j), function (error) {
                          console.trace(error.message);
                        });
}

function createCustomCallback(j){
  return function processResult(body) {

    // utilize j from the loop here to access the correct word in my array ($scope.motsCompares[j])

  }
}

Send arguments to a callback function within an Elasticsearch JavaScript API search query

Answer №1

Answer №2

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