datahub/src/backend/memory.js

this.recline = this.recline || {};
this.recline.Backend = this.recline.Backend || {};

(function($, my) {
  // ## createDataset
  //
  // Convenience function to create a simple 'in-memory' dataset in one step.
  //
  // @param data: list of hashes for each document/row in the data ({key:
  // value, key: value})
  // @param fields: (optional) list of field hashes (each hash defining a hash
  // as per recline.Model.Field). If fields not specified they will be taken
  // from the data.
  // @param metadata: (optional) dataset metadata - see recline.Model.Dataset.
  // If not defined (or id not provided) id will be autogenerated.
  my.createDataset = function(data, fields, metadata) {
    if (!metadata) {
      metadata = {};
    }
    if (!metadata.id) {
      metadata.id = String(Math.floor(Math.random() * 100000000) + 1);
    }
    var backend = new recline.Backend.Memory();
    var datasetInfo = {
      documents: data,
      metadata: metadata
    };
    if (fields) {
      datasetInfo.fields = fields;
    } else {
      if (data) {
        datasetInfo.fields = _.map(data[0], function(value, key) {
          return {id: key};
        });
      }
    }
    backend.addDataset(datasetInfo);
    var dataset = new recline.Model.Dataset({id: metadata.id}, backend);
    dataset.fetch();
    return dataset;
  };


  // ## Memory Backend - uses in-memory data
  //
  // To use it you should provide in your constructor data:
  // 
  //   * metadata (including fields array)
  //   * documents: list of hashes, each hash being one doc. A doc *must* have an id attribute which is unique.
  //
  // Example:
  // 
  //  <pre>
  //  // Backend setup
  //  var backend = recline.Backend.Memory();
  //  backend.addDataset({
  //    metadata: {
  //      id: 'my-id',
  //      title: 'My Title'
  //    },
  //    fields: [{id: 'x'}, {id: 'y'}, {id: 'z'}],
  //    documents: [
  //        {id: 0, x: 1, y: 2, z: 3},
  //        {id: 1, x: 2, y: 4, z: 6}
  //      ]
  //  });
  //  // later ...
  //  var dataset = Dataset({id: 'my-id'}, 'memory');
  //  dataset.fetch();
  //  etc ...
  //  </pre>
  my.Memory = my.Base.extend({
    __type__: 'memory',
    readonly: false,
    initialize: function() {
      this.datasets = {};
    },
    addDataset: function(data) {
      this.datasets[data.metadata.id] = $.extend(true, {}, data);
    },
    sync: function(method, model, options) {
      var self = this;
      var dfd = $.Deferred();
      if (method === "read") {
        if (model.__type__ == 'Dataset') {
          var rawDataset = this.datasets[model.id];
          model.set(rawDataset.metadata);
          model.fields.reset(rawDataset.fields);
          model.docCount = rawDataset.documents.length;
          dfd.resolve(model);
        }
        return dfd.promise();
      } else if (method === 'update') {
        if (model.__type__ == 'Document') {
          _.each(self.datasets[model.dataset.id].documents, function(doc, idx) {
            if(doc.id === model.id) {
              self.datasets[model.dataset.id].documents[idx] = model.toJSON();
            }
          });
          dfd.resolve(model);
        }
        return dfd.promise();
      } else if (method === 'delete') {
        if (model.__type__ == 'Document') {
          var rawDataset = self.datasets[model.dataset.id];
          var newdocs = _.reject(rawDataset.documents, function(doc) {
            return (doc.id === model.id);
          });
          rawDataset.documents = newdocs;
          dfd.resolve(model);
        }
        return dfd.promise();
      } else {
        alert('Not supported: sync on Memory backend with method ' + method + ' and model ' + model);
      }
    },
    query: function(model, queryObj) {
      var dfd = $.Deferred();
      var out = {};
      var numRows = queryObj.size;
      var start = queryObj.from;
      var results = this.datasets[model.id].documents;
      results = this._applyFilters(results, queryObj);
      results = this._applyFreeTextQuery(model, results, queryObj);
      // not complete sorting!
      _.each(queryObj.sort, function(sortObj) {
        var fieldName = _.keys(sortObj)[0];
        results = _.sortBy(results, function(doc) {
          var _out = doc[fieldName];
          return (sortObj[fieldName].order == 'asc') ? _out : -1*_out;
        });
      });
      out.facets = this._computeFacets(results, queryObj);
      var total = results.length;
      resultsObj = this._docsToQueryResult(results.slice(start, start+numRows));
      _.extend(out, resultsObj);
      out.total = total;
      dfd.resolve(out);
      return dfd.promise();
    },

    // in place filtering
    _applyFilters: function(results, queryObj) {
      _.each(queryObj.filters, function(filter) {
        results = _.filter(results, function(doc) {
          var fieldId = _.keys(filter.term)[0];
          return (doc[fieldId] == filter.term[fieldId]);
        });
      });
      return results;
    },

    // we OR across fields but AND across terms in query string
    _applyFreeTextQuery: function(dataset, results, queryObj) {
      if (queryObj.q) {
        var terms = queryObj.q.split(' ');
        results = _.filter(results, function(rawdoc) {
          var matches = true;
          _.each(terms, function(term) {
            var foundmatch = false;
            dataset.fields.each(function(field) {
              var value = rawdoc[field.id];
              if (value !== null) { value = value.toString(); }
              // TODO regexes?
              foundmatch = foundmatch || (value === term);
              // TODO: early out (once we are true should break to spare unnecessary testing)
              // if (foundmatch) return true;
            });
            matches = matches && foundmatch;
            // TODO: early out (once false should break to spare unnecessary testing)
            // if (!matches) return false;
          });
          return matches;
        });
      }
      return results;
    },

    _computeFacets: function(documents, queryObj) {
      var facetResults = {};
      if (!queryObj.facets) {
        return facetsResults;
      }
      _.each(queryObj.facets, function(query, facetId) {
        facetResults[facetId] = new recline.Model.Facet({id: facetId}).toJSON();
        facetResults[facetId].termsall = {};
      });
      // faceting
      _.each(documents, function(doc) {
        _.each(queryObj.facets, function(query, facetId) {
          var fieldId = query.terms.field;
          var val = doc[fieldId];
          var tmp = facetResults[facetId];
          if (val) {
            tmp.termsall[val] = tmp.termsall[val] ? tmp.termsall[val] + 1 : 1;
          } else {
            tmp.missing = tmp.missing + 1;
          }
        });
      });
      _.each(queryObj.facets, function(query, facetId) {
        var tmp = facetResults[facetId];
        var terms = _.map(tmp.termsall, function(count, term) {
          return { term: term, count: count };
        });
        tmp.terms = _.sortBy(terms, function(item) {
          // want descending order
          return -item.count;
        });
        tmp.terms = tmp.terms.slice(0, 10);
      });
      return facetResults;
    }
  });

}(jQuery, this.recline.Backend));