Aerospike: how do I get record key? - java

Aerospike client has scanAll method for reading all rows from it's store.
I use it in the folowing code:
ScanPolicy policy = new ScanPolicy();
policy.concurrentNodes = true;
policy.priority = Priority.DEFAULT;
policy.includeBinData = true;
policy.scanPercent = 100;
client.scanAll(policy, "namespaceName", "setName", new ScanCallback() {
#Override
public void scanCallback(Key key, Record record) throws AerospikeException {
STORE.put(key.userKey.toLong(), record.getValue("binName").toString());
}
});
But it is finished with NullPointerException, because userKey is null. All other fields are valid as expected. User key is the Long value, that was used for saving data:
client.put(writePolicy, new Key("namespaceName", "setName", userKey), new Bin("binName", value));
All is fine, if I do single request like this:
client.get(readPolicy, new Key("namespaceName", "setName", userKey));
What may be wrong? Why userKey is null?

Aerospike uses key and set name to generate unique digest, So it stores only digest.
While inserting one record if you set writePolicy.sendKey = true then key will be stored as metadata of record.
If one record is inserted with writePolicy.sendKey = true then only you will get key in scanCallback().
By default writePolicy.sendKey is false, so by default scanCallback() gets null as key. Thats why your key.userKey.toLong() gives NullPointerException.

I too have faced this problem even at the time of writing we were setting the WritePolicy.sendkeys=true.
After 2-3 days debugging found that there were some issue with aerospike client version. Initially i were using 3.0.25 but after upgrading it to 3.0.35 it started working fine.

Related

My Customer data is being truncated when added to my List [duplicate]

I am running data.bat file with the following lines:
Rem Tis batch file will populate tables
cd\program files\Microsoft SQL Server\MSSQL
osql -U sa -P Password -d MyBusiness -i c:\data.sql
The contents of the data.sql file is:
insert Customers
(CustomerID, CompanyName, Phone)
Values('101','Southwinds','19126602729')
There are 8 more similar lines for adding records.
When I run this with start > run > cmd > c:\data.bat, I get this error message:
1>2>3>4>5>....<1 row affected>
Msg 8152, Level 16, State 4, Server SP1001, Line 1
string or binary data would be truncated.
<1 row affected>
<1 row affected>
<1 row affected>
<1 row affected>
<1 row affected>
<1 row affected>
Also, I am a newbie obviously, but what do Level #, and state # mean, and how do I look up error messages such as the one above: 8152?
From #gmmastros's answer
Whenever you see the message....
string or binary data would be truncated
Think to yourself... The field is NOT big enough to hold my data.
Check the table structure for the customers table. I think you'll find that the length of one or more fields is NOT big enough to hold the data you are trying to insert. For example, if the Phone field is a varchar(8) field, and you try to put 11 characters in to it, you will get this error.
I had this issue although data length was shorter than the field length.
It turned out that the problem was having another log table (for audit trail), filled by a trigger on the main table, where the column size also had to be changed.
In one of the INSERT statements you are attempting to insert a too long string into a string (varchar or nvarchar) column.
If it's not obvious which INSERT is the offender by a mere look at the script, you could count the <1 row affected> lines that occur before the error message. The obtained number plus one gives you the statement number. In your case it seems to be the second INSERT that produces the error.
Just want to contribute with additional information: I had the same issue and it was because of the field wasn't big enough for the incoming data and this thread helped me to solve it (the top answer clarifies it all).
BUT it is very important to know what are the possible reasons that may cause it.
In my case i was creating the table with a field like this:
Select '' as Period, * From Transactions Into #NewTable
Therefore the field "Period" had a length of Zero and causing the Insert operations to fail. I changed it to "XXXXXX" that is the length of the incoming data and it now worked properly (because field now had a lentgh of 6).
I hope this help anyone with same issue :)
Some of your data cannot fit into your database column (small). It is not easy to find what is wrong. If you use C# and Linq2Sql, you can list the field which would be truncated:
First create helper class:
public class SqlTruncationExceptionWithDetails : ArgumentOutOfRangeException
{
public SqlTruncationExceptionWithDetails(System.Data.SqlClient.SqlException inner, DataContext context)
: base(inner.Message + " " + GetSqlTruncationExceptionWithDetailsString(context))
{
}
/// <summary>
/// PArt of code from following link
/// http://stackoverflow.com/questions/3666954/string-or-binary-data-would-be-truncated-linq-exception-cant-find-which-fiel
/// </summary>
/// <param name="context"></param>
/// <returns></returns>
static string GetSqlTruncationExceptionWithDetailsString(DataContext context)
{
StringBuilder sb = new StringBuilder();
foreach (object update in context.GetChangeSet().Updates)
{
FindLongStrings(update, sb);
}
foreach (object insert in context.GetChangeSet().Inserts)
{
FindLongStrings(insert, sb);
}
return sb.ToString();
}
public static void FindLongStrings(object testObject, StringBuilder sb)
{
foreach (var propInfo in testObject.GetType().GetProperties())
{
foreach (System.Data.Linq.Mapping.ColumnAttribute attribute in propInfo.GetCustomAttributes(typeof(System.Data.Linq.Mapping.ColumnAttribute), true))
{
if (attribute.DbType.ToLower().Contains("varchar"))
{
string dbType = attribute.DbType.ToLower();
int numberStartIndex = dbType.IndexOf("varchar(") + 8;
int numberEndIndex = dbType.IndexOf(")", numberStartIndex);
string lengthString = dbType.Substring(numberStartIndex, (numberEndIndex - numberStartIndex));
int maxLength = 0;
int.TryParse(lengthString, out maxLength);
string currentValue = (string)propInfo.GetValue(testObject, null);
if (!string.IsNullOrEmpty(currentValue) && maxLength != 0 && currentValue.Length > maxLength)
{
//string is too long
sb.AppendLine(testObject.GetType().Name + "." + propInfo.Name + " " + currentValue + " Max: " + maxLength);
}
}
}
}
}
}
Then prepare the wrapper for SubmitChanges:
public static class DataContextExtensions
{
public static void SubmitChangesWithDetailException(this DataContext dataContext)
{
//http://stackoverflow.com/questions/3666954/string-or-binary-data-would-be-truncated-linq-exception-cant-find-which-fiel
try
{
//this can failed on data truncation
dataContext.SubmitChanges();
}
catch (SqlException sqlException) //when (sqlException.Message == "String or binary data would be truncated.")
{
if (sqlException.Message == "String or binary data would be truncated.") //only for EN windows - if you are running different window language, invoke the sqlException.getMessage on thread with EN culture
throw new SqlTruncationExceptionWithDetails(sqlException, dataContext);
else
throw;
}
}
}
Prepare global exception handler and log truncation details:
protected void Application_Error(object sender, EventArgs e)
{
Exception ex = Server.GetLastError();
string message = ex.Message;
//TODO - log to file
}
Finally use the code:
Datamodel.SubmitChangesWithDetailException();
Another situation in which you can get this error is the following:
I had the same error and the reason was that in an INSERT statement that received data from an UNION, the order of the columns was different from the original table. If you change the order in #table3 to a, b, c, you will fix the error.
select a, b, c into #table1
from #table0
insert into #table1
select a, b, c from #table2
union
select a, c, b from #table3
on sql server you can use SET ANSI_WARNINGS OFF like this:
using (SqlConnection conn = new SqlConnection("Data Source=XRAYGOAT\\SQLEXPRESS;Initial Catalog='Healthy Care';Integrated Security=True"))
{
conn.Open();
using (var trans = conn.BeginTransaction())
{
try
{
using cmd = new SqlCommand("", conn, trans))
{
cmd.CommandText = "SET ANSI_WARNINGS OFF";
cmd.ExecuteNonQuery();
cmd.CommandText = "YOUR INSERT HERE";
cmd.ExecuteNonQuery();
cmd.Parameters.Clear();
cmd.CommandText = "SET ANSI_WARNINGS ON";
cmd.ExecuteNonQuery();
trans.Commit();
}
}
catch (Exception)
{
trans.Rollback();
}
}
conn.Close();
}
I had the same issue. The length of my column was too short.
What you can do is either increase the length or shorten the text you want to put in the database.
Also had this problem occurring on the web application surface.
Eventually found out that the same error message comes from the SQL update statement in the specific table.
Finally then figured out that the column definition in the relating history table(s) did not map the original table column length of nvarchar types in some specific cases.
I had the same problem, even after increasing the size of the problematic columns in the table.
tl;dr: The length of the matching columns in corresponding Table Types may also need to be increased.
In my case, the error was coming from the Data Export service in Microsoft Dynamics CRM, which allows CRM data to be synced to an SQL Server DB or Azure SQL DB.
After a lengthy investigation, I concluded that the Data Export service must be using Table-Valued Parameters:
You can use table-valued parameters to send multiple rows of data to a Transact-SQL statement or a routine, such as a stored procedure or function, without creating a temporary table or many parameters.
As you can see in the documentation above, Table Types are used to create the data ingestion procedure:
CREATE TYPE LocationTableType AS TABLE (...);
CREATE PROCEDURE dbo.usp_InsertProductionLocation
#TVP LocationTableType READONLY
Unfortunately, there is no way to alter a Table Type, so it has to be dropped & recreated entirely. Since my table has over 300 fields (😱), I created a query to facilitate the creation of the corresponding Table Type based on the table's columns definition (just replace [table_name] with your table's name):
SELECT 'CREATE TYPE [table_name]Type AS TABLE (' + STRING_AGG(CAST(field AS VARCHAR(max)), ',' + CHAR(10)) + ');' AS create_type
FROM (
SELECT TOP 5000 COLUMN_NAME + ' ' + DATA_TYPE
+ IIF(CHARACTER_MAXIMUM_LENGTH IS NULL, '', CONCAT('(', IIF(CHARACTER_MAXIMUM_LENGTH = -1, 'max', CONCAT(CHARACTER_MAXIMUM_LENGTH,'')), ')'))
+ IIF(DATA_TYPE = 'decimal', CONCAT('(', NUMERIC_PRECISION, ',', NUMERIC_SCALE, ')'), '')
AS field
FROM INFORMATION_SCHEMA.COLUMNS
WHERE TABLE_NAME = '[table_name]'
ORDER BY ORDINAL_POSITION) AS T;
After updating the Table Type, the Data Export service started functioning properly once again! :)
When I tried to execute my stored procedure I had the same problem because the size of the column that I need to add some data is shorter than the data I want to add.
You can increase the size of the column data type or reduce the length of your data.
A 2016/2017 update will show you the bad value and column.
A new trace flag will swap the old error for a new 2628 error and will print out the column and offending value. Traceflag 460 is available in the latest cumulative update for 2016 and 2017:
https://support.microsoft.com/en-sg/help/4468101/optional-replacement-for-string-or-binary-data-would-be-truncated
Just make sure that after you've installed the CU that you enable the trace flag, either globally/permanently on the server:
...or with DBCC TRACEON:
https://learn.microsoft.com/en-us/sql/t-sql/database-console-commands/dbcc-traceon-trace-flags-transact-sql?view=sql-server-ver15
Another situation, in which this error may occur is in
SQL Server Management Studio. If you have "text" or "ntext" fields in your table,
no matter what kind of field you are updating (for example bit or integer).
Seems that the Studio does not load entire "ntext" fields and also updates ALL fields instead of the modified one.
To solve the problem, exclude "text" or "ntext" fields from the query in Management Studio
This Error Comes only When any of your field length is greater than the field length specified in sql server database table structure.
To overcome this issue you have to reduce the length of the field Value .
Or to increase the length of database table field .
If someone is encountering this error in a C# application, I have created a simple way of finding offending fields by:
Getting the column width of all the columns of a table where we're trying to make this insert/ update. (I'm getting this info directly from the database.)
Comparing the column widths to the width of the values we're trying to insert/ update.
Assumptions/ Limitations:
The column names of the table in the database match with the C# entity fields. For eg: If you have a column like this in database:
You need to have your Entity with the same column name:
public class SomeTable
{
// Other fields
public string SourceData { get; set; }
}
You're inserting/ updating 1 entity at a time. It'll be clearer in the demo code below. (If you're doing bulk inserts/ updates, you might want to either modify it or use some other solution.)
Step 1:
Get the column width of all the columns directly from the database:
// For this, I took help from Microsoft docs website:
// https://learn.microsoft.com/en-us/dotnet/api/system.data.sqlclient.sqlconnection.getschema?view=netframework-4.7.2#System_Data_SqlClient_SqlConnection_GetSchema_System_String_System_String___
private static Dictionary<string, int> GetColumnSizesOfTableFromDatabase(string tableName, string connectionString)
{
var columnSizes = new Dictionary<string, int>();
using (var connection = new SqlConnection(connectionString))
{
// Connect to the database then retrieve the schema information.
connection.Open();
// You can specify the Catalog, Schema, Table Name, Column Name to get the specified column(s).
// You can use four restrictions for Column, so you should create a 4 members array.
String[] columnRestrictions = new String[4];
// For the array, 0-member represents Catalog; 1-member represents Schema;
// 2-member represents Table Name; 3-member represents Column Name.
// Now we specify the Table_Name and Column_Name of the columns what we want to get schema information.
columnRestrictions[2] = tableName;
DataTable allColumnsSchemaTable = connection.GetSchema("Columns", columnRestrictions);
foreach (DataRow row in allColumnsSchemaTable.Rows)
{
var columnName = row.Field<string>("COLUMN_NAME");
//var dataType = row.Field<string>("DATA_TYPE");
var characterMaxLength = row.Field<int?>("CHARACTER_MAXIMUM_LENGTH");
// I'm only capturing columns whose Datatype is "varchar" or "char", i.e. their CHARACTER_MAXIMUM_LENGTH won't be null.
if(characterMaxLength != null)
{
columnSizes.Add(columnName, characterMaxLength.Value);
}
}
connection.Close();
}
return columnSizes;
}
Step 2:
Compare the column widths with the width of the values we're trying to insert/ update:
public static Dictionary<string, string> FindLongBinaryOrStringFields<T>(T entity, string connectionString)
{
var tableName = typeof(T).Name;
Dictionary<string, string> longFields = new Dictionary<string, string>();
var objectProperties = GetProperties(entity);
//var fieldNames = objectProperties.Select(p => p.Name).ToList();
var actualDatabaseColumnSizes = GetColumnSizesOfTableFromDatabase(tableName, connectionString);
foreach (var dbColumn in actualDatabaseColumnSizes)
{
var maxLengthOfThisColumn = dbColumn.Value;
var currentValueOfThisField = objectProperties.Where(f => f.Name == dbColumn.Key).First()?.GetValue(entity, null)?.ToString();
if (!string.IsNullOrEmpty(currentValueOfThisField) && currentValueOfThisField.Length > maxLengthOfThisColumn)
{
longFields.Add(dbColumn.Key, $"'{dbColumn.Key}' column cannot take the value of '{currentValueOfThisField}' because the max length it can take is {maxLengthOfThisColumn}.");
}
}
return longFields;
}
public static List<PropertyInfo> GetProperties<T>(T entity)
{
//The DeclaredOnly flag makes sure you only get properties of the object, not from the classes it derives from.
var properties = entity.GetType()
.GetProperties(System.Reflection.BindingFlags.Public
| System.Reflection.BindingFlags.Instance
| System.Reflection.BindingFlags.DeclaredOnly)
.ToList();
return properties;
}
Demo:
Let's say we're trying to insert someTableEntity of SomeTable class that is modeled in our app like so:
public class SomeTable
{
[Key]
public long TicketID { get; set; }
public string SourceData { get; set; }
}
And it's inside our SomeDbContext like so:
public class SomeDbContext : DbContext
{
public DbSet<SomeTable> SomeTables { get; set; }
}
This table in Db has SourceData field as varchar(16) like so:
Now we'll try to insert value that is longer than 16 characters into this field and capture this information:
public void SaveSomeTableEntity()
{
var connectionString = "server=SERVER_NAME;database=DB_NAME;User ID=SOME_ID;Password=SOME_PASSWORD;Connection Timeout=200";
using (var context = new SomeDbContext(connectionString))
{
var someTableEntity = new SomeTable()
{
SourceData = "Blah-Blah-Blah-Blah-Blah-Blah"
};
context.SomeTables.Add(someTableEntity);
try
{
context.SaveChanges();
}
catch (Exception ex)
{
if (ex.GetBaseException().Message == "String or binary data would be truncated.\r\nThe statement has been terminated.")
{
var badFieldsReport = "";
List<string> badFields = new List<string>();
// YOU GOT YOUR FIELDS RIGHT HERE:
var longFields = FindLongBinaryOrStringFields(someTableEntity, connectionString);
foreach (var longField in longFields)
{
badFields.Add(longField.Key);
badFieldsReport += longField.Value + "\n";
}
}
else
throw;
}
}
}
The badFieldsReport will have this value:
'SourceData' column cannot take the value of
'Blah-Blah-Blah-Blah-Blah-Blah' because the max length it can take is
16.
Kevin Pope's comment under the accepted answer was what I needed.
The problem, in my case, was that I had triggers defined on my table that would insert update/insert transactions into an audit table, but the audit table had a data type mismatch where a column with VARCHAR(MAX) in the original table was stored as VARCHAR(1) in the audit table, so my triggers were failing when I would insert anything greater than VARCHAR(1) in the original table column and I would get this error message.
I used a different tactic, fields that are allocated 8K in some places. Here only about 50/100 are used.
declare #NVPN_list as table
nvpn varchar(50)
,nvpn_revision varchar(5)
,nvpn_iteration INT
,mpn_lifecycle varchar(30)
,mfr varchar(100)
,mpn varchar(50)
,mpn_revision varchar(5)
,mpn_iteration INT
-- ...
) INSERT INTO #NVPN_LIST
SELECT left(nvpn ,50) as nvpn
,left(nvpn_revision ,10) as nvpn_revision
,nvpn_iteration
,left(mpn_lifecycle ,30)
,left(mfr ,100)
,left(mpn ,50)
,left(mpn_revision ,5)
,mpn_iteration
,left(mfr_order_num ,50)
FROM [DASHBOARD].[dbo].[mpnAttributes] (NOLOCK) mpna
I wanted speed, since I have 1M total records, and load 28K of them.
This error may be due to less field size than your entered data.
For e.g. if you have data type nvarchar(7) and if your value is 'aaaaddddf' then error is shown as:
string or binary data would be truncated
You simply can't beat SQL Server on this.
You can insert into a new table like this:
select foo, bar
into tmp_new_table_to_dispose_later
from my_table
and compare the table definition with the real table you want to insert the data into.
Sometime it's helpful sometimes it's not.
If you try inserting in the final/real table from that temporary table it may just work (due to data conversion working differently than SSMS for example).
Another alternative is to insert the data in chunks, instead of inserting everything immediately you insert with top 1000 and you repeat the process, till you find a chunk with an error. At least you have better visibility on what's not fitting into the table.

RabbitMQ parsing "client_properties" header from c#

I'm listening for connection changes through events pluging ("amq.rabbitmq.event", "connection.#").
It works properly so I'm adding at java side two additional parameters as clientproperties, to get the identity of the user that connects or disconnect.
However at c# side I can only access these properties as a list of byte[], and not sure on how to convert it to a Dictionary or so..
If I print all entries
if (args.BasicProperties.Headers.TryGetValue("client_properties", out object value))
{
var items = value as List<object>;
foreach(var item in items)
{
Console.WriteLine($"{item.GetType().ToString()}");
var bytes = item as byte[];
result.Add(Encoding.UTF8.GetString(bytes));
}
}
I can see this:
{<<"platform">>,longstr,<<"Java">>}
{<<"capabilities">>,table,[{<<"connection.blocked">>,bool,true},{<<"basic.nack">>,bool,true},{<<"exchange_exchange_bindings">>,bool,true},{<<"authentication_failure_close">>,bool,true},{<<"publisher_confirms">>,bool,true},{<<"consumer_cancel_notify">>,bool,true}]}
{<<"groupId">>,longstr,<<"1e6e935f0d4d9ec446d67dadc85cbafd10d1a095">>}
{<<"information">>,longstr,<<"Licensed under the MPL. See http://www.rabbitmq.com/">>}
{<<"version">>,longstr,<<"4.8.1">>}
{<<"copyright">>,longstr,<<"Copyright (c) 2007-2018 Pivotal Software, Inc.">>}
{<<"product">>,longstr,<<"RabbitMQ">>}
What kind of object format is and how can I parse this?:
{<<id>>,type,<<value>>}
Apparently ( as for an answer I got on Rabbit client google group for this questions ), client_properties is something that's not created to being read by the receiving party..
However is a really good way to have something like LWT ( Last Will and Testament ), then I am using it at the minute doing the parse by myself.
if (args.BasicProperties.Headers.TryGetValue("client_properties", out object value))
{
var items = value as List<object>;
foreach (var item in items)
{
var bytes = item as byte[];
//{<<id>>, type, <<value>>}
String itemStr = Encoding.UTF8.GetString(bytes);
var parts = itemStr.Split(",");
var key = CleanErlangString(parts[0]);
var value = CleanErlangString(parts[2]);
// Do things with key/value
}
}
ClearErlangFunction
private static string CleanErlangString(string toClean)
{
return toClean
.Replace("{", "").Replace("}", "")
.Replace("\"", "")
.Replace("<<", "").Replace(">>", "");
}
What I am doing to use it as LWT, is setting a custom property on client side and then obtaining it while reading events at "amq.rabbitmq.event", "connection.#". With that I know who have disconnected and even process something as LWT with my core server.
I hope this helps someone :)

Unable to get UniqueIdentifier from X500Principal of X509Certificate

I wanted to get the unique identifier of a X509Certificate using Java.
I tried to get the value from using the below code:-
java.security.cert.X509Certificate certificate=// certificate object
certificate.getSubjectX500Principal().getName();
But i am unable to get the unique identifier value alone.This is the value i am getting:-
2.5.4.45=#0309000000db000000a01a,OU=06
I wanted to get the value alone for "2.5.4.45".
I also tried to get the value using the below code:-
String dn2 = certificate.getSubjectX500Principal().getName();
LdapName ldapDN;
ldapDN = new LdapName(dn2);
for(Rdn rdn: ldapDN.getRdns()) {
System.out.println(rdn.getType() + " -> " + rdn.getValue());
if(rdn.getType().equalsIgnoreCase("2.5.4.45")){
System.out.println(rdn.getValue());
}
I am getting an object as the value for unique identifier. I am not able to parse the Object, get the value for this.
Update ::
I am still not able to figure out a way to get the UniqueIdentifier identifer.Any help is appreciated.
You need provide set of known OIDs. Then you will get a human readable value of DN String. Value of known OIDs will be readable when you define OID. For example:
Map<String, String> knownOids = new HashMap<String, String>();
knownOids.put("2.5.4.45", "uniqueIdentifier");
String humanReadableDN = certToken.getCertificate().getSubjectX500Principal().getName(X500Principal.RFC2253, knownOids);
Example OID repository you can find here: http://oid-info.com/get/2.5.4.45
For Example, this:
CN=Krzysiek,1.2.840.113549.1.9.1=#160f3334353334354064666766642e706c
Will be translated to this:
commonName=Krzysiek,emailAddress=345345#dfgfd.pl
When you provide a set with:
knownOids.put("1.2.840.113549.1.9.1", "emailAddress");

hbase java code returns null for a get but hbase shell get comman returns record

I have just started using hbase and also not a proficient java programmer. I created a debug program to test the current hbase program that does put & get records and also as a deduping mechanism. The debug program checks to see if certain ids are present in the hbase table that should have been inserted using the other program. When I do a get, for the most part records are there but some will be returned as null (not found). When I manually check from the hbase shell and request the same id, it returns the row with timestamp. Is there something I am not understanding here? Are there multiple versions of a record kept in hbase? I assumed hbase made unique records based on the id provided.
// code to get record
public static byte[] getPreHbase(String provid, String commentId) throws IOException {
provid = "98";
commentId = commentId.trim();
String rec = provid + "." + commentId;
byte [] value= "test".getBytes();
try{
Get g = new Get(Bytes.toBytes(rec));
Result r = htableII.get(g);
value = r.getValue(Bytes.toBytes("cmmnttest"),Bytes.toBytes("cmmntposts"));
String valueStr = Bytes.toString(value);
}catch (Exception e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
return value;
As I mentioned this is only sometimes for some ids while others are returned. This is the manual call in shell
get 'hb_test', '98.1010000000003_1asdfghjkl'
COLUMN CELL
cmmnttest:cmmntposts timestamp=1420659812914,
value= 1010000000003_1asdfghjkl
1 row(s) in 0.0140 seconds

I am not able to delete data from Datastore in Google App Engine for Java?

I have assigned key to every entity in my Data store. but when i click on delete , i am not able to delete it ..Please help me regarding that.
I have created a function "deleteuser()" inside my SAFCServlet.java class , which i am trying to invoke when trying to delete .My function is :
SAFCServlet.java
.............
public static void deleteuser(string name)
{
Key UserKey = KeyFactory.createKey("safc",name );
System.out.println("the value od userkey is" +UserKey);
ds.delete(UserKey);
}
above function i am calling from Delete.java Servlet
Delete.java
..................
String key1=req.getParameter("key").toString();
PrintWriter out = resp.getWriter();
out.println("I m in delete");
System.out.println("the first key is "+key1);
SAFCServlet.deleteuser(key1);
The above Servlet "Delete.java" gets called when i click on delete,but i am not able to delete .please help me with that.The "key1" in above function is the key (this key is usergenerated not the inbuilt key of data store) of every entry in my datastore
MY TABLE IS .For Example:
KIND is "safc" (means Table name)
key|Title(data)|Author
78 |john |laxmi
99 |Andy |ashish
We can create any entity like this in datastore :
Entity e = new Entity("safc");
e.setParameter("username");
e.setParameter("password");
e.setParameter("Key");
ds.put(e);
While trying to delete from datastore i am getting error in my code and i am not able to resolve it.code i used is shown above in" Delete.java" servlet and "SAFCServlet.java" , i found this somewhere and i was trying to implement it.
you are missing the datastore API initialization in deleteuser() function
Try this
Delete.java
String key1=req.getParameter("key").toString();
PrintWriter out = resp.getWriter();
out.println("I m in delete");
System.out.println("the first key is "+key1);
Datastore ds= DatastoreServiceFactory.getDatastoreService();
Key UserKey = KeyFactory.createKey("safc",key1 );
System.out.println("the value od userkey is" +UserKey);
ds.delete(UserKey);
String key1=req.getParameter("key");
Datastore ds= DatastoreServiceFactory.getDatastoreService();
Key UserKey = KeyFactory.createKey("safc",key1 ); // Key key = KeyFactory.createKey("KIND",ID);
ds.delete(UserKey); //delete(key)

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