1 | <?php |
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23 | class DBALQueryInterface implements QueryInterface { |
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24 | |||
25 | /** |
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26 | * @var Connection |
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27 | */ |
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28 | private $connection; |
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29 | |||
30 | /** |
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31 | * @since 0.1 |
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32 | * |
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33 | * @param Connection $connection |
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34 | */ |
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35 | public function __construct( Connection $connection ) { |
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38 | |||
39 | /** |
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40 | * @see QueryInterface::tableExists |
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41 | * |
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42 | * @since 0.1 |
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43 | * |
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44 | * @param string $tableName |
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45 | * |
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46 | * @return bool |
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47 | */ |
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48 | public function tableExists( $tableName ) { |
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51 | |||
52 | /** |
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53 | * @see QueryInterface::insert |
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54 | * |
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55 | * @since 0.1 |
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56 | * |
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57 | * @param string $tableName |
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58 | * @param array $values |
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59 | * |
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60 | * @throws InsertFailedException |
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61 | */ |
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62 | public function insert( $tableName, array $values ) { |
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70 | |||
71 | /** |
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72 | * @see QueryInterface::update |
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73 | * |
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74 | * @since 0.1 |
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75 | * |
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76 | * @param string $tableName |
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77 | * @param array $values |
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78 | * @param array $conditions |
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79 | * |
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80 | * @throws UpdateFailedException |
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81 | */ |
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82 | public function update( $tableName, array $values, array $conditions ) { |
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90 | |||
91 | /** |
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92 | * @see QueryInterface::delete |
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93 | * |
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94 | * @since 0.1 |
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95 | * |
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96 | * @param string $tableName |
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97 | * @param array $conditions |
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98 | * |
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99 | * @throws DeleteFailedException |
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100 | */ |
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101 | public function delete( $tableName, array $conditions ) { |
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109 | |||
110 | /** |
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111 | * @see QueryInterface::getInsertId |
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112 | * |
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113 | * @since 0.1 |
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114 | * |
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115 | * @throws QueryInterfaceException |
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116 | * @return int |
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117 | */ |
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118 | public function getInsertId() { |
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126 | |||
127 | /** |
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128 | * @see QueryInterface::select |
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129 | * |
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130 | * @since 0.1 |
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131 | * |
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132 | * @param string $tableName |
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133 | * @param string[] $fieldNames |
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134 | * @param array $conditions |
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135 | * @param array $options |
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136 | * |
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137 | * @throws SelectFailedException |
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138 | * @return Iterator |
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139 | */ |
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140 | public function select( $tableName, array $fieldNames, array $conditions, array $options = array() ) { |
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153 | |||
154 | /** |
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155 | * @param string $tableName |
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156 | * @param array $fields |
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157 | * |
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158 | * @return QueryBuilder |
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159 | */ |
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160 | private function newQueryBuilderFor( $tableName, array $fields ) { |
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174 | |||
175 | /** |
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176 | * @param QueryBuilder $queryBuilder |
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177 | * @param array $conditions |
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178 | */ |
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179 | private function addConditionsToQueryBuilder( QueryBuilder $queryBuilder, array $conditions ) { |
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185 | |||
186 | } |
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187 |
If you return a value from a function or method, it should be a sub-type of the type that is given by the parent type f.e. an interface, or abstract method. This is more formally defined by the Lizkov substitution principle, and guarantees that classes that depend on the parent type can use any instance of a child type interchangably. This principle also belongs to the SOLID principles for object oriented design.
Let’s take a look at an example:
Our function
my_function
expects aPost
object, and outputs the author of the post. The base classPost
returns a simple string and outputting a simple string will work just fine. However, the child classBlogPost
which is a sub-type ofPost
instead decided to return anobject
, and is therefore violating the SOLID principles. If aBlogPost
were passed tomy_function
, PHP would not complain, but ultimately fail when executing thestrtoupper
call in its body.