[641] | 1 | /* Copyright 2010 the original author or authors. |
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| 2 | * |
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| 3 | * Licensed under the Apache License, Version 2.0 (the "License"); |
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| 4 | * you may not use this file except in compliance with the License. |
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| 5 | * You may obtain a copy of the License at |
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| 6 | * |
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| 7 | * http://www.apache.org/licenses/LICENSE-2.0 |
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| 8 | * |
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| 9 | * Unless required by applicable law or agreed to in writing, software |
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| 10 | * distributed under the License is distributed on an "AS IS" BASIS, |
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| 11 | * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
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| 12 | * See the License for the specific language governing permissions and |
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| 13 | * limitations under the License. |
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| 14 | */ |
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| 15 | |
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| 16 | /** |
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| 17 | * Provides a DSL for building and managing HQL strings. |
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| 18 | * For usage examples see the HqlBuilderTests. |
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| 19 | * HQL reference see http://docs.jboss.org/hibernate/core/3.6/reference/en-US/html/queryhql.html |
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| 20 | * |
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| 21 | * Primary goals: |
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| 22 | * 1. Easy to read and understand in code. |
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| 23 | * 2. Easy to read and understand when printed (e.g when displayed in a report). |
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| 24 | * 3. Easy to execute with correct paginateParams and namedParams. |
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| 25 | * 4. Easy to change a clause and execute again. |
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| 26 | * |
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| 27 | * @author Gavin Kromhout |
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| 28 | * @version DraftA |
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| 29 | * |
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| 30 | */ |
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| 31 | class HqlBuilder { |
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| 32 | |
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| 33 | // Query clauses. |
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| 34 | // Each clause is a key with a list of terms. |
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| 35 | def clauses = [:] |
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| 36 | |
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| 37 | // HQL namedParams. |
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| 38 | // HQL requires the namedParams to match exactly with the clause expressions. |
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| 39 | def namedParams = [:] |
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| 40 | |
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| 41 | // HQL paginateParams. |
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| 42 | def paginateParams = [max: 1000, offset: 0] |
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| 43 | |
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| 44 | // It is easier and more flexible to simply add order as a clause, e.g: order 'by id asc' |
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| 45 | //def sort = "" // e.g. instanceName.id |
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| 46 | //def order = "" // e.g. asc or desc |
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| 47 | |
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| 48 | def HqlBuilder(debug = false) { |
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| 49 | if(!super.metaClass.hasMetaProperty('log')) |
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| 50 | mockLogging(debug) |
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| 51 | log.debug "HqlBuilder()" |
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| 52 | } |
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| 53 | |
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| 54 | def call() { |
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| 55 | log.debug "call()" |
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| 56 | } |
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| 57 | |
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| 58 | /** |
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| 59 | * Call with closure as last arg. |
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| 60 | * A typically used build call, e.g: q { } is equivalent to q.call() { } |
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| 61 | */ |
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| 62 | def call(Closure cl) { |
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| 63 | log.debug "call(Closure cl)" |
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| 64 | handleClosure(cl) |
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| 65 | } |
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| 66 | |
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| 67 | /** |
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| 68 | * Domain specific build method. |
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| 69 | * Has no real use other than to prevent obscure errors |
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| 70 | * when user makes a call to query() and Groovy calls query(Closure cl) |
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| 71 | * @returns This object. |
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| 72 | */ |
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| 73 | def query() { |
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| 74 | log.debug "query()" |
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| 75 | return this // Must return this object to q. |
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| 76 | } |
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| 77 | |
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| 78 | /** |
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| 79 | * Domain specific build method. |
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| 80 | * A typically used build call, e.g: def q = new HqlBuilder().query { } |
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| 81 | * |
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| 82 | * @param cl The supplied Closure. |
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| 83 | * @returns This object. |
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| 84 | * |
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| 85 | */ |
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| 86 | def query(Closure cl) { |
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| 87 | log.debug "query(Closure cl)" |
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| 88 | handleClosure(cl) |
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| 89 | return this // Must return this object to q. |
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| 90 | } |
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| 91 | |
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| 92 | /** |
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| 93 | * InvokeMethod resolves all undefined methods. |
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| 94 | * Which include the clause methods, e.g select 'book' is equivalent to select('book'). |
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| 95 | * Note that defined methods will be called directly since this class does not implement GroovyInterceptable. |
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| 96 | * If class was "HqlBuilder implements GroovyInterceptable" then even println would be intercepted and |
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| 97 | * several exlusions might be needed. e.g: if(methodName != 'call' && methodName != 'println') |
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| 98 | */ |
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| 99 | def invokeMethod(String name, args) { |
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| 100 | |
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| 101 | log.debug "invokeMethod(${methodName}, ${args})" |
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| 102 | |
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| 103 | if(!this.clauses[name]) |
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| 104 | this.clauses[name] = [] |
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| 105 | |
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| 106 | for(arg in args) { |
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| 107 | if(arg instanceof String) |
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| 108 | this.clauses[name] << arg |
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| 109 | } |
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| 110 | |
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| 111 | if(args[-1] instanceof Closure) |
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| 112 | handleClosure(args[-1]) |
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| 113 | |
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| 114 | } // invokeMethod() |
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| 115 | |
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| 116 | /** |
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| 117 | * PropertyMissing. |
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| 118 | * Allows clauses to be added after build, e.g: q.order = 'by book.name asc' |
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| 119 | * and clauses to be removed, e.g: q.order = null |
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| 120 | */ |
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| 121 | def propertyMissing(String name, value) { |
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| 122 | log.debug "propertyMissing(${propertyName}, ${value})" |
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| 123 | if(value == null) { |
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| 124 | clauses.remove(name) |
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| 125 | return |
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| 126 | } |
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| 127 | |
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| 128 | if(value instanceof String) |
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| 129 | clauses[name] = [value] |
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| 130 | } |
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| 131 | |
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| 132 | /** |
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| 133 | * PropertyMissing. |
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| 134 | * Allow clauses to be accessed directly by name, e.g: println q.order. |
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| 135 | * Since clauses is a Map null is simply returned for a non-existant clause. |
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| 136 | */ |
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| 137 | def propertyMissing(String name) { |
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| 138 | log.debug "propertyMissing(${name})" |
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| 139 | clauses[name] |
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| 140 | } |
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| 141 | |
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| 142 | /** |
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| 143 | * HandleClosure. |
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| 144 | * Setting delegate and DELEGATE_FIRST allows closure to access this object's properties first. |
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| 145 | */ |
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| 146 | private handleClosure(Closure cl) { |
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| 147 | cl.delegate = this |
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| 148 | cl.resolveStrategy = Closure.DELEGATE_FIRST |
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| 149 | cl.call() |
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| 150 | } |
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| 151 | |
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| 152 | /** |
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| 153 | * MockLogging. |
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| 154 | * This class has super cow powers and can mock out it's own debug logging. |
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| 155 | */ |
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| 156 | private mockLogging(debug = false) { |
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| 157 | def mockLogger = {} |
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| 158 | if(debug) { |
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| 159 | mockLogger = {msg -> |
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| 160 | println "${super.getClass()} - DEBUG: $msg" |
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| 161 | } |
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| 162 | } |
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| 163 | super.metaClass.log = [debug: mockLogger] |
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| 164 | log.debug "Internal mockLogger configured." |
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| 165 | } |
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| 166 | |
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| 167 | /** |
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| 168 | * GetQuery. |
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| 169 | * Assemble and return the query in a format that can be directly executed. |
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| 170 | * E.g: executeQuery(q.query, q.namedParams, q.paginateParams). |
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| 171 | */ |
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| 172 | def getQuery() { |
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| 173 | this.clauses.collect { |
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| 174 | it.key + ' ' + it.value.join(' ') |
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| 175 | }.join(' ') |
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| 176 | } |
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| 177 | |
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| 178 | /** |
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| 179 | * GetPrintFormattedQuery. |
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| 180 | * Assemble and return the query in a format that can be more easily printed and read by a person. |
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| 181 | * E.g: println q.printFormattedQuery or when displayed in a report. |
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| 182 | */ |
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| 183 | def getPrintFormattedQuery() { |
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| 184 | this.clauses.collect { |
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| 185 | it.key + ' ' + it.value.join(' \n') |
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| 186 | }.join(' \n') |
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| 187 | } |
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| 188 | |
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| 189 | } // end class |
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