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var assign = require('object-assign');
var pluralize = require('pluralize');
var isarray = require('lodash.isarray');
var Q = require('q');
var OKQuery = require('okquery');
var OKResource = require('okresource');
// Routes for views over collections have a special pattern
// containing a free variable e.g. :id
var UNBOUND_ROUTE_PATTERN = /:([a-zA-Z\-_]+)/;
/**
* OKView!
* Is supplied DB queries and a template and is responsible
* for resolving the queries, throwing the data into the templates,
* and sending the response.
*/
function OKView(options) {
if (!(this instanceof OKView)) return new OKView(options);
options = options || {};
if (!options.template)
throw new Error('No template provided to OKView.');
if (!options.meta)
throw new Error('No metadata provided to OKView');
if (!options.route)
throw new Error('No route provided to OKView');
if (!options.errorHandler)
throw new Error('No error handler provided to OKView');
var route = options.route;
var mount = options.mount || 'get';
var error = this._error = options.errorHandler;
this._template = options.template;
var meta = this._meta = options.meta;
var queries = this._queries = options.queries || [];
// Whether this is a view for a specific resource or its
// resource will be resolved later
// TODO This bound / unbound thing can probably be expressed in a
// less convoluted way.
var unbound = this.unbound = !!UNBOUND_ROUTE_PATTERN.exec(route);
Object.defineProperty(this, 'mount', {
value: mount,
writable: false,
enumerable: true
});
Object.defineProperty(this, 'route', {
value: route,
writable: false,
enumerable: true
});
this._middleware = unbound
? unboundMiddleware(this, meta, queries, error)
: boundMiddleware(this, meta, queries, error);
}
OKView.prototype.middleware = function() {
return this._middleware;
};
OKView.prototype.render = function(req, res, data) {
this._template.render(data).then(function(html) {
res.send(html);
}).fail(this._error(req, res, 500));
};
/**
* Creates middleware for a view which does not
* yet have a resource id associated with it
*/
function unboundMiddleware(view, meta, queries, error) {
var paramName = getParamName(view.route);
return function(req, res, next) {
var id = req.params[paramName];
fetchTemplateData(meta, queries, id).then(function(data) {
view.render(req, res, data);
}).fail(failHandler(req, res, error));
};
}
/**
* Creates middleware for a view which already
* has a resource id associated with it
*/
function boundMiddleware(view, meta, queries, error) {
return function(req, res, next) {
fetchTemplateData(meta, queries).then(function(data) {
view.render(req, res, data);
}).fail(failHandler(req, res, error));
};
}
function failHandler(req, res, error) {
return function (err) {
// TODO Use custom exception type
if (err.message === 'No resource found') {
error(req, res, 404)(err);
} else {
error(req, res, 500)(err);
}
}
}
/**
* Given a route with a free variable, return the
* name of the variable, e.g. :id returns id
*/
function getParamName(route) {
route = route || '';
var matches = UNBOUND_ROUTE_PATTERN.exec(route) || [];
return matches[1];
}
/**
* Takes a meta data query and an array of resource queries
* and returns a promise for an object merging all queried
* data, pluralizing keys where necessary.
*
* Pretty convoluted, sorry.
*/
function fetchTemplateData(meta, queries, id) {
// If there's only one query, we assume it is for a single
// resource and will resolve errors if no data is found
var single = queries && queries.length === 1;
return Q.promise(function(resolve, reject) {
return Q.all(queries.map(function(query) {
return query.get(id);
})).then(function(results) {
if (single && !results[0]) {
reject(new Error('No resource found'));
} else {
var normalized = results.reduce(function(cache, result, i) {
// Could be just some rogue request
if (!result) {
return cache;
}
var query = queries[i]
var resource = query.resource;
var type = query.as || query.type;
var manyResult = isarray(result);
var groupBy = query.groupBy
// If we have a lot of results for a certain type,
// we pluralize the key and yield an array of results
if (cache[type] || manyResult || groupBy) {
var plural = pluralize(type);
delete cache[type];
cache[plural] = [];
// Pluralize grouped field
if (query.groupBy) {
result = Object.keys(result).reduce(function(acc, key) {
acc[pluralize(key)] = result[key]
return acc
}, {})
}
if (manyResult) {
cache[plural] = cache[plural].concat(result);
} else if (groupBy) {
cache[plural] = result
} else {
cache[plural].push(result);
}
} else {
cache[type] = result;
}
return cache;
}, {meta: meta});
resolve(normalized);
}
}).fail(reject);
});
}
module.exports = OKView;
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