lib/Ext/data/association/HasOne.js
function(record, reader, associationData) {
        var inverse = this.getInverseAssociation(),
            newRecord = reader.read([associationData]).getRecords()[0];

        record[this.getSetterName()].call(record, newRecord);

        //if the inverse association was found, set it now on each record we've just created
        if (inverse) {
            newRecord[inverse.getInstanceName()] = record;
        }
    }
function(record, reader, associationData) {
        var inverse = this.getInverseAssociation(),
            newRecord = reader.read([associationData]).getRecords()[0];

        record[this.getSetterName()].call(record, newRecord);

        //if the inverse association was found, set it now on each record we've just created
        if (inverse) {
            newRecord[inverse.getInstanceName()] = record;
        }
    }
Read associated data
@private
@param {Ext.data.Model} record The record we're writing to
@param {Ext.data.reader.Reader} reader The reader for the associated model
@param {Object} associationData The raw associated data