json格式在ruby和rails中的注意事项

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  #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

ruby关于json格式的调用

首先json格式注意：

1、在nodes后面要紧跟:，不能有空格

2、nodes、name这些地方不能用引号括起来，不然不能用ruby转换为json格式

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。