jsonsql

http://www.trentrichardson.com/jsonsql/

可以对json数组用sql语法进行操作，主要是查询取指定字段、条件、指定字段排序及获取多少条数据，返回值json。

jsonsql.query("select * from json.channel.items order by title desc",json); 

jsonsql.query("select title,url from json.channel.items where (category=='javascript' || category=='vista') order by title,category asc limit 3",json); 

开发例子：

var hospitals=[{"a":"1","b":"2","c":"3"},{"a":"3","b":"4","c":"5"}];
var b=jsonsql.query("select a,b from json where (a=='3') order by a ",hospitals);

结果：

[{
　　"a" : "3",
　　"b" : "4"
}]

 

js库源码

/*
* JsonSQL
* By: Trent Richardson [http://trentrichardson.com]
* Version 0.1
* Last Modified: 1/1/2008
*
* Copyright 2008 Trent Richardson
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/

var jsonsql = {

query: function(sql,json){

var returnfields = sql.match(/^(select)\s+([a-z0-9_\,\.\s\*]+)\s+from\s+([a-z0-9_\.]+)(?: where\s+\((.+)\))?\s*(?:order\sby\s+([a-z0-9_\,]+))?\s*(asc|desc|ascnum|descnum)?\s*(?:limit\s+([0-9_\,]+))?/i);

var ops = {
fields: returnfields[2].replace(' ','').split(','),
from: returnfields[3].replace(' ',''),
where: (returnfields[4] == undefined)? "true":returnfields[4],
orderby: (returnfields[5] == undefined)? []:returnfields[5].replace(' ','').split(','),
order: (returnfields[6] == undefined)? "asc":returnfields[6],
limit: (returnfields[7] == undefined)? []:returnfields[7].replace(' ','').split(',')
};

return this.parse(json, ops);
},

parse: function(json,ops){
var o = { fields:["*"], from:"json", where:"", orderby:[], order: "asc", limit:[] };
for(i in ops) o[i] = ops[i];

var result = [];
result = this.returnFilter(json,o);
result = this.returnOrderBy(result,o.orderby,o.order);
result = this.returnLimit(result,o.limit);

return result;
},

returnFilter: function(json,jsonsql_o){

var jsonsql_scope = eval(jsonsql_o.from);
var jsonsql_result = [];
var jsonsql_rc = 0;

if(jsonsql_o.where == "")
jsonsql_o.where = "true";

for(var jsonsql_i in jsonsql_scope){
with(jsonsql_scope[jsonsql_i]){
if(eval(jsonsql_o.where)){
jsonsql_result[jsonsql_rc++] = this.returnFields(jsonsql_scope[jsonsql_i],jsonsql_o.fields);
}
}
}

return jsonsql_result;
},

returnFields: function(scope,fields){
if(fields.length == 0)
fields = ["*"];

if(fields[0] == "*")
return scope;

var returnobj = {};
for(var i in fields)
returnobj[fields[i]] = scope[fields[i]];

return returnobj;
},

returnOrderBy: function(result,orderby,order){
if(orderby.length == 0)
return result;

result.sort(function(a,b){
switch(order.toLowerCase()){
case "desc": return (eval('a.'+ orderby[0] +' < b.'+ orderby[0]))? 1:-1;
case "asc": return (eval('a.'+ orderby[0] +' > b.'+ orderby[0]))? 1:-1;
case "descnum": return (eval('a.'+ orderby[0] +' - b.'+ orderby[0]));
case "ascnum": return (eval('b.'+ orderby[0] +' - a.'+ orderby[0]));
}
});

return result;
},

returnLimit: function(result,limit){
switch(limit.length){
case 0: return result;
case 1: return result.splice(0,limit[0]);
case 2: return result.splice(limit[0]-1,limit[1]);
}
}

};