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116 lines
3.0 KiB
116 lines
3.0 KiB
/**
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* Handle models (i.e. docs)
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* Serialization/deserialization
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* Copying
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*/
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var dateToJSON = function () { return { $$date: this.getTime() }; }
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, originalDateToJSON = Date.prototype.toJSON
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/**
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* Check a key, throw an error if the key is non valid
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* @param {String} k key
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* @param {Model} v value, needed to treat the Date edge case
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* Non-treatable edge case here: if part of the object if of the form { $$date: number }
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* Its serialized-then-deserialized version it will transformed into a Date object
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* But you really need to want it to trigger such behaviour, even when warned not to use '$' at the beginning of the field names...
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*/
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function checkKey (k, v) {
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if (k[0] === '$' && !(k === '$$date' && typeof v === 'number')) {
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throw 'Keys cannot begin with the $ character';
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}
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}
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/**
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* Serialize an object to be persisted to a one-line string
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* Accepted primitive types: Number, String, Boolean, Date, null
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* Accepted secondary types: Objects, Arrays
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*/
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function serialize (obj) {
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var res;
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// Keep track of the fact that this is a Date object
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Date.prototype.toJSON = dateToJSON;
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res = JSON.stringify(obj, function (k, v) {
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checkKey(k, v);
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if (typeof v === 'string' || typeof v === 'number' || typeof v === 'boolean' || v === null) { return v; }
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//if (v && v.constructor && v.constructor.name === 'Date') { console.log("==============="); return { $$date: v.toString() }; }
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return v;
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});
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// Return Date to its original state
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Date.prototype.toJSON = originalDateToJSON;
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return res;
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}
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/**
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* From a one-line representation of an object generate by the serialize function
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* Return the object itself
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*/
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function deserialize (rawData) {
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return JSON.parse(rawData, function (k, v) {
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if (k === '$$date') { return new Date(v); }
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if (typeof v === 'string' || typeof v === 'number' || typeof v === 'boolean' || v === null) { return v; }
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if (v && v.$$date) { return v.$$date; }
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return v;
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});
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}
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/**
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* Deep copy a DB object
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*/
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function deepCopy (obj) {
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var res;
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if ( typeof obj === 'boolean' ||
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typeof obj === 'number' ||
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typeof obj === 'string' ||
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obj === null ||
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(obj && obj.constructor && obj.constructor.name === 'Date') ) {
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return obj;
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}
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if (obj instanceof Array) {
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res = [];
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obj.forEach(function (o) { res.push(o); });
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return res;
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}
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if (typeof obj === 'object') {
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res = {};
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Object.keys(obj).forEach(function (k) {
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checkKey(k, obj[k]);
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res[k] = deepCopy(obj[k]);
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});
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return res;
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}
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return undefined; // For now everything else is undefined. We should probably throw an error instead
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}
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/**
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* Modify a DB object according to an update query
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* For now the updateQuery only replaces the object
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*/
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function modify (obj, updateQuery) {
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updateQuery = deepCopy(updateQuery);
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updateQuery._id = obj._id;
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return updateQuery;
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};
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// Interface
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module.exports.serialize = serialize;
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module.exports.deserialize = deserialize;
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module.exports.deepCopy = deepCopy;
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module.exports.modify = modify;
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