如何强制 Mybatis 使用动态条件进行区分大小写的选择

Question

I'm constructing a dynamic query for a Mybatis DB mapper, to access a MySql database. The query is driven by an XML config file containing select fields. So I dynamically create a critera object. My problem is, if one of the select fields is a string, the select returns unwanted records due to it being case insensitive

For example, if the select value is 'Analog1', this will match a record with value 'analog1'.

Question is, can I force the underlying SELECT to be case sensitive? I know that

select * from Label where binary Label_Name = 'analog1';

Will only match 'analog1' and not 'Analog1'. But how to tell the Mybatis query to use the binary qualifier in the query?

Here's my code to create the criteria. As you can see it's all dynamically done using reflection, there's nothing hardcoded:

private Object findMatchingRecord(TLVMessageHandlerData data, Object databaseMapperObject, Object domainObject, ActiveRecordDataType activeRecordData)
        throws TLVMessageHandlerException {

    if (activeRecordData == null) {
        return false;
    }

    String domainClassName = domainObject.getClass().getName();

    try {
        String exampleClassName = domainClassName + "Example";
        Class<?> exampleClass = Class.forName(exampleClassName);
        Object exampleObject = exampleClass.newInstance();
        Method createCriteriaMethod = exampleClass.getDeclaredMethod("createCriteria", (Class<?>[])null);
        Object criteriaObject = createCriteriaMethod.invoke(exampleObject, (Object[])null);

        for (String selectField : activeRecordData.getSelectField()) {
            String criteriaMethodName = "and" + firstCharToUpper(selectField) + "EqualTo";
            Class<?> selectFieldType = domainObject.getClass().getDeclaredField(selectField).getType();
            Method criteriaMethod = criteriaObject.getClass().getMethod(criteriaMethodName, selectFieldType);
            Method getSelectFieldMethod = domainObject.getClass().getDeclaredMethod("get" + firstCharToUpper(selectField));
            Object selectFieldValue = getSelectFieldMethod.invoke(domainObject, (Object[])null);
            if (selectFieldValue != null) {
                criteriaMethod.invoke(criteriaObject, new Object[] { selectFieldValue });
            }
        }

        List<?> resultSet = tlvMessageProcessingDelegate.selectByExample(databaseMapperObject, exampleObject);

        if (resultSet.size() > 0) {
            return resultSet.get(0);
        }
        else {
            return null;
        }

    } 
    catch(..... Various exceptions.....) {
    }

Answer 1

There's a way to do this by modifying the 'Example' class used to create query criteria. Suppose you have a Mybatis domain object called Label . This will have an associated LabelExample . Notice I've added the 'binary' qualifier to the generated criteria method. This appears to do the job for me, and results in a case sensitive query.

public class LabelExample {

...

/**
 * This class was generated by MyBatis Generator. This class corresponds to the database table Label
 * @mbggenerated
 */
    protected abstract static class GeneratedCriteria {

        public Criteria andLabelNameEqualTo(String value) {
            addCriterion("binary Label_Name =", value, "labelName");
            return (Criteria) this;
        }
    ...
}

Answer 2

I believe it's possible to do, but not using the simple queries style.

That's defined in the Mybatis Generator doc as this form:

TestTableExample example = new TestTableExample();
example.createCriteria().andField1EqualTo("abc");

Which results in a query filter like this:

where field1 = 'abc'

Instead, I think you need to use the complex queries form and combine it with a plugin to enable ILIKE -esque searches.

There is an example of such a plugin that ships with mybatis-generator . I reproduce the code below for completeness:

/*
 *  Copyright 2009 The Apache Software Foundation
 *
 *  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.
 */

package org.mybatis.generator.plugins;

import java.util.List;

import org.mybatis.generator.api.PluginAdapter;
import org.mybatis.generator.api.IntrospectedColumn;
import org.mybatis.generator.api.IntrospectedTable;
import org.mybatis.generator.api.dom.java.FullyQualifiedJavaType;
import org.mybatis.generator.api.dom.java.InnerClass;
import org.mybatis.generator.api.dom.java.JavaVisibility;
import org.mybatis.generator.api.dom.java.Method;
import org.mybatis.generator.api.dom.java.Parameter;
import org.mybatis.generator.api.dom.java.TopLevelClass;
import org.mybatis.generator.codegen.ibatis2.Ibatis2FormattingUtilities;

/**
 * This plugin demonstrates adding methods to the example class to enable
 * case-insensitive LIKE searches. It shows hows to construct new methods and
 * add them to an existing class.
 * 
 * This plugin only adds methods for String fields mapped to a JDBC character
 * type (CHAR, VARCHAR, etc.)
 * 
 * @author Jeff Butler
 * 
 */
public class CaseInsensitiveLikePlugin extends PluginAdapter {

    /**
     * 
     */
    public CaseInsensitiveLikePlugin() {
        super();
    }

    public boolean validate(List<String> warnings) {
        return true;
    }

    @Override
    public boolean modelExampleClassGenerated(TopLevelClass topLevelClass,
            IntrospectedTable introspectedTable) {

        InnerClass criteria = null;
        // first, find the Criteria inner class
        for (InnerClass innerClass : topLevelClass.getInnerClasses()) {
            if ("GeneratedCriteria".equals(innerClass.getType().getShortName())) { //$NON-NLS-1$
                criteria = innerClass;
                break;
            }
        }

        if (criteria == null) {
            // can't find the inner class for some reason, bail out.
            return true;
        }

        for (IntrospectedColumn introspectedColumn : introspectedTable
                .getNonBLOBColumns()) {
            if (!introspectedColumn.isJdbcCharacterColumn()
                    || !introspectedColumn.isStringColumn()) {
                continue;
            }

            Method method = new Method();
            method.setVisibility(JavaVisibility.PUBLIC);
            method.addParameter(new Parameter(introspectedColumn
                    .getFullyQualifiedJavaType(), "value")); //$NON-NLS-1$

            StringBuilder sb = new StringBuilder();
            sb.append(introspectedColumn.getJavaProperty());
            sb.setCharAt(0, Character.toUpperCase(sb.charAt(0)));
            sb.insert(0, "and"); //$NON-NLS-1$
            sb.append("LikeInsensitive"); //$NON-NLS-1$
            method.setName(sb.toString());
            method.setReturnType(FullyQualifiedJavaType.getCriteriaInstance());

            sb.setLength(0);
            sb.append("addCriterion(\"upper("); //$NON-NLS-1$
            sb.append(Ibatis2FormattingUtilities
                    .getAliasedActualColumnName(introspectedColumn));
            sb.append(") like\", value.toUpperCase(), \""); //$NON-NLS-1$
            sb.append(introspectedColumn.getJavaProperty());
            sb.append("\");"); //$NON-NLS-1$
            method.addBodyLine(sb.toString());
            method.addBodyLine("return (Criteria) this;"); //$NON-NLS-1$

            criteria.addMethod(method);
        }

        return true;
    }
}

It seems kind of painful to implement, and unfortunately, as seems to often be the case with advanced Mybatis features, the only doc is really the example checked into the git repo.

You may want to look at using the SQL Builder class built in to Mybatis , where you could use the WHERE method and specify ILIKE in the argument, although I know that may be a bridge too far given the current usage of the generator code.

Answer 3

There is a mybatis generator plugin org.mybatis.generator.plugins.CaseInsensitiveLikePlugin

This plugin adds methods to the Example class (actually to the Criteria inner class) to support case insensitive LIKE searches

You can use insensitive like 'XXXX', it can work with any database