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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 meta resource provided to OKView');
if (!options.route)
throw new Error('No route provided to OKView');
var route = options.route;
var mount = options.mount || 'get';
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 = createMiddleware(this);
this._fetchTemplateData = unbound ? fetchUnbound : fetchBound;
function fetchUnbound(id) {
return fetchTemplateData(meta, queries, id)
}
function fetchBound() {
return fetchTemplateData(meta, queries);
}
}
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(errorHandler(req, res, data));
};
OKView.prototype.fetchTemplateData = function() {
return this._fetchTemplateData.apply(this, arguments);
};
/**
* Unbound views need different middleware to resolve requests
*/
function createMiddleware(view) {
if (view.unbound) {
return unboundMiddleware(view);
} else {
return boundMiddleware(view);
}
}
// Note that these middleware do not call next
// and should thus always be added at the end of the
// middleware chain.
/**
* Creates middleware for a view which does not
* yet have a resource id associated with it
*/
function unboundMiddleware(view) {
var paramName = getParamName(view.route);
return function(req, res, next) {
var id = req.params[paramName];
view.fetchTemplateData(id).then(function(data) {
view.render(req, res, data);
}).fail(errorHandler(req, res, next));
};
}
/**
* Creates middleware for a view which already
* has a resource id associated with it
*/
function boundMiddleware(view) {
return function(req, res, next) {
view.fetchTemplateData().then(function(data) {
view.render(req, res, data);
}).fail(errorHandler(req, res, next));
};
}
/**
* TODO BS error handling for now
*/
function errorHandler(req, res, next) {
return function(err) {
res.send(err.stack);
}
}
/**
* 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.
*
* Lil bit convoluted, sorry.
*/
function fetchTemplateData(meta, queries, id) {
return Q.promise(function(resolve, reject) {
return Q.all(
[meta.get()].concat(queries.map(function(query) {
return query.get(id);
})))
.then(function(results) {
var metadata = results.shift();
var normalized = results.reduce(function(cache, result, i) {
// Could be just some rogue request
if (!result) {
return cache;
}
var resource = queries[i].resource;
var type = queries[i].type;
var manyResult = isarray(result);
// Inform template of ID in generic field
if (manyResult) {
result = result.map(function(data) {
return assign({}, data, {id: data[resource.idField]})
});
} else {
result = assign({}, result, {id: result[resource.idField]});
}
// 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) {
var plural = pluralize(type);
delete cache[type];
cache[plural] = [];
if (manyResult) {
cache[plural] = cache[plural].concat(result);
} else {
cache[plural].push(result);
}
} else {
cache[type] = result;
}
return cache;
}, {meta: metadata});
resolve(normalized);
}).fail(reject);
});
}
module.exports = OKView;
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