json格式在ruby和rails中的注意事项

#虚拟网络拓扑的json数据
def topodata
#@vnic = Vnic.all
#flash.now[:notice] = 'Message sent!'
#flash.now[:alert] = 'Message sent!'
simple_json = {
nodes: [{ name: 'bob', age: "22", awesome: "true" }, { name: 'bob', age: 22, awesome:true }],
links: [{ name: 'bob', age: "22", awesome: "true" }, { name: 'bob', age: 22, awesome:true }]
}
vnet = Vnet.find(:all, :select => 'id,name,vswitch_id')
vm = VirtualMachine.find(:all, :select => 'id,hostname,virtual_machine_container_id')
vmc = VirtualMachineContainer.find(:all, :select => 'id,hostname')
vswitch = Vswitch.find(:all, :select => 'id,uuid,virtual_machine_container_id,vnet_id,name')  #vswitch 和 vmc有什么关系？
vnic = Vnic.find(:all, :select => 'id,virtual_machine_id,vnet_id')
#把所有的name放入nodes数组中 如：{"name":"vswitch1","type":"vswitch"}
nodes = Array.new
for i in 0..vswitch.size-1 do
nodes.push({
name: vswitch[i].name.to_s,
group: 1 #"vswitch"
})
end
for i in 0..vm.size-1 do
nodes.push({
name: vm[i].hostname.to_s,
group: 2 #"vm"
})
end
for i in 0..vmc.size-1 do
nodes.push({
name: vmc[i].hostname.to_s,
group: 3 #"vmc"
})
end
#储存名字和其在nodes中的位置,为了方便edges找到其位置    如：id_hash["vm2"] = 4
id_hash = Hash.new
for i in 0..nodes.size-1 do
id_hash[nodes[i][:name]] = i
end
#edges储存边之间的关系
#先储存vswitch和vm的关系 => vnic
links = Array.new
for i in 0..vnic.size-1 do
links.push({
source: id_hash[vm[vnic[i].virtual_machine_id-1].hostname],
target: id_hash[vswitch[vnet[vnic[i].vnet_id-1].vswitch_id-1].name],
value: 10,
des: "vswitch_to_vm"
})
end
#再储存vm和vmc的关系 => vm
for i in 0..vm.size-1 do
links.push({
source: id_hash[vm[i].hostname],
target: id_hash[vmc[vm[i].virtual_machine_container_id-1].hostname],
value: 5,
des: "vm_to_vmc"
})
end
@alljson = {}
@alljson["nodes"] = nodes
@alljson["links"] = links
#flash.now[:alert] = id_hash[vm[2].hostname]
lsjson = {
nodes: [
{name:"Myriel",group:1},
{name:"Napoleon",group:1},
{name:"Mlle.Baptistine",group:2},
],
links: [
{source:0,target:1,value:1},
{source:1,target:2,value:8},
{source:2,target:1,value:10},
]
}
respond_to do |format|
format.html
format.json { render json: @alljson }  #这里会自动调用to_json
end
#render json: lsjson
#render json: {test: 1}
end

simple_json = {
nodes: [{ name: 'bob', age: "22", awesome: "true" }, { name: 'bob', age: 22, awesome:true }],
links: [{ name: 'bob', age: "22", awesome: "true" }, { name: 'bob', age: 22, awesome:true }]
}

3、(1)可以直接在controller的方法中直接render，就可以得到json格式的数据，比如

render json: simple_json

(2)或者另一种方法也可以，这里的@alljson就是类似上面simple_json格式的数据，当然，如果直接是model里导出来的数据也可以直接用，比如@vnic = Vnic.all

respond_to do |format|
format.html
format.json { render json: @alljson }  #这里会自动调用to_json
end

4、直接访问url   http://localhost:3000/vnet/topodata.json就可以直接得到json数据了 
在rubychina上看到如果在url上想不要后面.json就可以看到json数据的话，就要到route里改resource直接为json数据了， routes里面对特定的resource加上 
format: :json好像是这样。