我正在开发一个 Spring MVC 项目，我需要获取所选 Postgres 数据库的表和属性，并在页面加载后立即将它们存储在数组中。
我目前已经编写了以下 ajax 调用，通过它我能够检索表格并显示在相应的数据库下。
VisualEditor.js
drop: function (e, ui) {
var mouseTop = e.clientY;
var mouseLeft = e.clientX;
var dropElem = ui.draggable.attr('class');
droppedElement = ui.helper.clone();
ui.helper.remove();
$(droppedElement).removeAttr("class");
$(droppedElement).draggable({containment: "container"});
jsPlumb.repaint(ui.helper);
//If the dropped Element is a TABLE then->
if (dropElem == "stream ui-draggable ui-draggable-handle") {
var newAgent = $('<div>');
jsPlumb.addEndpoint(newAgent,connectorProperties);
newAgent.attr('id', i).addClass('streamdrop');
var elemType = "table";
$("#container").addClass("disabledbutton");
$("#toolbox").addClass("disabledbutton");
$('#container').append(newAgent);
$.ajax({
type: "post",
url: "http://localhost:8080/controllers/tables",
cache: false,
success: function(response){
if (response !== "{}"){
var array = response.replace("{", "").replace("}", "");
var index = array.indexOf("[") +1;
var stringval = array.split(":");
var stringval2 = array.substring(index,array.indexOf("]")).split(",");
var db_names = new Array();
var table_names = new Array();
var column_names = new Array();
for(var i = 0 ;i < stringval.length-1 ;i++)
{
db_names[i] = eval(stringval[i]);
if(db_names[i]=="testdb"){
var StreamArray = new Array();
}
var listId = "db"+i;
var dropdownId ="mydrpdown"+i;
table_names[i] = new Array();
$("#lot").append(
"<li onclick='myFunction(\""+dropdownId+"\","+i+","+stringval2.length+")' class='list-group-item dropbtn' id='"+listId+"'> " + db_names[i] +
"</li> "+
"<div id='" + dropdownId +"' class='dropdown-content'> " +
"<a onclick='setDatabase(\""+db_names[i]+"\",\""+listId+"\")'> Make This as Default Database</a>"+
"</div>"
);
$("#databaseID").append(
"<option>" + db_names[i] +"</option>"
);
for(var j=0;j < stringval2.length;j++)
{
/**
* Loading the Predefined Databases and Tables of the Connected DB
*/
var table_id= "tableId"+i+j;
if( eval(stringval2[j]) != null){
table_names[i][j] = eval(stringval2[j]);
if(db_names[i]=="testdb")
{
StreamArray[j] = new Array(4);
StreamArray[j][0] = table_names[i][j];
/**
* table_names array values at the moment are:
* customer,department and students
* So the following ajax call should pass each table name to the listTables
* method in the controller and fetch the respective columns of each table
*/
$.ajax({
type: "post",
url: "http://localhost:8080/controllers/listTables/{tablename}",
data: { tablename: table_names[i][j]} ,
cache: false,
success: function(response){
if (response !== "{}"){
var array = response.replace("{", "").replace("}", "");
var index = array.indexOf("[") +1;
var stringval = array.split(":");
var stringval2 = array.substring(index,array.indexOf("]")).split(",");
var db_names = new Array();
var table_names = new Array();
var column_names = new Array();
for(var i = 0 ;i < stringval.length-1 ;i++){
}
}
}
});
}
$("#lot").append(
"<li class='list-group-item'style = 'display:none' id='"+table_id+"'> "+table_names[i][j]+" </li>");
}
}
$("#lot").append(
"</br>");
array = array.slice(array.indexOf("]") +2);
index = array.indexOf("[") +1;
stringval2 = array.substring(index,array.indexOf("]")).split(",");
}
}
},
error: function(xhr, status, error){
alert("Error while loading the query");
}
});
$("property").show();
$(".toolbox-titlex").show();
$(".panel").show();
我已经编写了 2 个嵌入其中的 ajax 调用，以首先获取 table_names，然后获取 column_names。但我猜测这不是一种非常有效的方法。但我不确定如何同时获得两者。
EditorController.java
@RequestMapping(value= "/tables", method = RequestMethod.POST)
public @ResponseBody
String tables(HttpServletRequest request, HttpServletResponse response)
throws Exception {
Map<String, List<String>> alvalues = new HashMap<String, List<String>>();;
String queryString = request.getParameter("query");
// ApplicationContext context = new ClassPathXmlApplicationContext("Spring-Module.xml");
//CustomerDao customerDAO = (CustomerDao) context.getBean("CustomerDao");
alvalues = customerDAO.getAllTables();
Gson gson = new Gson();
String element = gson.toJson(alvalues);
System.out.println(element);
return element;
}
@RequestMapping(value= "/listTables/{tablename}", method = RequestMethod.POST)
public @ResponseBody
String listTables(HttpServletRequest request, HttpServletResponse response,@PathVariable("tablename") String tablename)
throws Exception {
Map<String, List<String>> alvalues = new HashMap<String, List<String>>();;
String queryString = request.getParameter("query");
alvalues = customerDAO.getAllFields(tablename);
Gson gson = new Gson();
String element = gson.toJson(alvalues);
System.out.println(element);
return element;
}
CustomerDAO.java
public Map<String, List<String>> getAllTables();
public Map<String, List<String>> getAllFields(String tablename);
jdbcCustomerDAO.java
public Map<String, List<String>> getAllTables(){
int k = 1;
Map<String, List<String>> map = new HashMap<String, List<String>>();
ArrayList<String> databases = getAllDatabse();
String sql = "SELECT table_name FROM information_schema.tables WHERE table_schema='public'";
Connection conn = null;
for(int i=0;i<=databases.size();i++)
{
try {
Class.forName("org.postgresql.Driver");
conn = DriverManager.getConnection(
"jdbc:postgresql://localhost:5432/"+databases.get(i),"postgres", "123");
PreparedStatement ps = conn.prepareStatement(sql,ResultSet.TYPE_SCROLL_INSENSITIVE,
ResultSet.CONCUR_UPDATABLE);
ResultSet rs = ps.executeQuery();
ArrayList<String> alvalues = new ArrayList<String>();
while(rs.next()){
alvalues.add(rs.getString(1));
}
map.put(databases.get(i), alvalues);
rs.beforeFirst();
for (Map.Entry<String, List<String>> entry : map.entrySet()) {
String key = entry.getKey();
List<String> values = entry.getValue();
System.out.println("Key = " + key);
System.out.println("Values = " + values + "n");
}
conn.close();
}
catch(Exception e){
System.out.println(e.getMessage());
}
}
return map;
}
public Map<String, List<String>> getAllFields(String tablename){
int k = 1;
Map<String, List<String>> map = new HashMap<String, List<String>>();
ArrayList<String> databases = getAllDatabse();
String sql = "SELECT column_name FROM INFORMATION_SCHEMA.COLUMNS WHERE TABLE_NAME = '"+tablename+"'";
Connection conn = null;
for(int i=0;i<=databases.size();i++)
{
try {
Class.forName("org.postgresql.Driver");
conn = DriverManager.getConnection(
"jdbc:postgresql://localhost:5432/"+databases.get(i),"postgres", "123");
PreparedStatement ps = conn.prepareStatement(sql,ResultSet.TYPE_SCROLL_INSENSITIVE,
ResultSet.CONCUR_UPDATABLE);
ResultSet rs = ps.executeQuery();
ArrayList<String> alvalues = new ArrayList<String>();
while(rs.next()){
alvalues.add(rs.getString(1));
}
map.put(databases.get(i), alvalues);
rs.beforeFirst();
for (Map.Entry<String, List<String>> entry : map.entrySet()) {
String key = entry.getKey();
List<String> values = entry.getValue();
System.out.println("Key = " + key);
System.out.println("Values = " + values + "n");
}
conn.close();
}
catch(Exception e){
System.out.println(e.getMessage());
}
}
return map;
}
但我无法成功获取列名。
控制台日志
According to this, the table_names are successfully retrieved but the column names are empty.
INFO : com.postgres.controllers.HomeController - Welcome home! The client locale is en_US.
postgres
postgreside
testdb
Key = postgres
Values = []n
Key = postgreside
Values = [constraints, users, notes, session, projects, databases, tables, columns, index, checksconstraint, additionalproperties, foreignref, primaryref, referenceproperties, department, person]n
Key = postgres
Values = []n
Key = testdb
Values = [customer, department, students]n
Key = postgreside
Values = [constraints, users, notes, session, projects, databases, tables, columns, index, checksconstraint, additionalproperties, foreignref, primaryref, referenceproperties, department, person]n
Key = postgres
Values = []n
Index: 3, Size: 3
{"testdb":["customer","department","students"],"postgreside":["constraints","users","notes","session","projects","databases","tables","columns","index","checksconstraint","additionalproperties","foreignref","primaryref","referenceproperties","department","person"],"postgres":[]}
postgres
postgreside
testdb
postgres
postgreside
testdb
postgres
postgreside
testdb
Key = postgres
Values = []n
Key = postgres
Values = []n
Key = postgres
Values = []n
Key = postgreside
Values = []n
Key = postgres
Values = []n
Key = postgreside
Values = []n
Key = postgres
Values = []n
Key = postgreside
Values = []n
Key = postgres
Values = []n
Key = testdb
Values = []n
Key = postgreside
Values = []n
Key = postgres
Values = []n
Index: 3, Size: 3
{"testdb":[],"postgreside":[],"postgres":[]}
Key = testdb
Values = []n
Key = postgreside
Values = []n
Key = postgres
Values = []n
Index: 3, Size: 3
{"testdb":[],"postgreside":[],"postgres":[]}
Key = testdb
Values = []n
Key = postgreside
Values = []n
Key = postgres
Values = []n
Index: 3, Size: 3
{"testdb":[],"postgreside":[],"postgres":[]}
我想要一个方法来检索表名及其属性/列并将其存储在 StreamArray 中，这样我就不需要在每次需要引用时都访问数据库到相关数据。
对于如何获取列名称并将其存储在我在 VisualEditor.js 下创建的 StreamArray 中的任何建议，我们将不胜感激。
最佳答案
一般情况下，你可以处理多个数据库，多个schema，每个表名可以出现在多个schema中。在您的情况下，您可能需要排除更多模式。或者您可能决定只有模式“public”是相关的。 (要小心这样的决定。)
select table_catalog, table_schema, table_name, column_name
from information_schema.columns
where table_catalog = 'your_db_name'
and table_schema <> 'information_schema'
and table_schema <> 'pg_catalog'
order by table_catalog, table_schema, table_name, column_name;
关于ajax - 在 Postgres 中检索数据库的列和表，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/46276056/