|
| 1 | +[[adding-missing-overloaded-api-methods]] |
| 2 | += Adding Missing Overloaded API Methods |
| 3 | + |
| 4 | +This section covers how to add your own overloaded API methods to implement new functionality. |
| 5 | + |
| 6 | +[[implementing-custom-search-methods]] |
| 7 | +== Implementing Custom Search Methods |
| 8 | + |
| 9 | +`LdapTemplate` contains several overloaded versions of the most common operations in `DirContext`. However, we have not provided an alternative for each and every method signature, mostly because there are so many of them. We have, however, provided a means to call whichever `DirContext` method you want and still get the benefits that `LdapTemplate` provides. |
| 10 | + |
| 11 | +Suppose you want to call the following `DirContext` method: |
| 12 | + |
| 13 | +==== |
| 14 | +[source,java] |
| 15 | +[subs="verbatim,quotes"] |
| 16 | +---- |
| 17 | +NamingEnumeration search(Name name, String filterExpr, Object[] filterArgs, SearchControls ctls) |
| 18 | +---- |
| 19 | +==== |
| 20 | + |
| 21 | +There is no corresponding overloaded method in `LdapTemplate`. The way to solve this is to use a custom `SearchExecutor` implementation, as follows: |
| 22 | + |
| 23 | +==== |
| 24 | +[source,java] |
| 25 | +[subs="verbatim,quotes"] |
| 26 | +---- |
| 27 | +public interface SearchExecutor { |
| 28 | + public NamingEnumeration executeSearch(DirContext ctx) throws NamingException; |
| 29 | +} |
| 30 | +---- |
| 31 | +==== |
| 32 | + |
| 33 | +In your custom executor, you have access to a `DirContext` object, which you can use to call the method you want. You can then provide a handler that is responsible for mapping attributes and collecting the results. You can, for example, use one of the available implementations of `CollectingNameClassPairCallbackHandler`, which collects the mapped results in an internal list. In order to actually perform the search, you need to call the `search` method in `LdapTemplate` that takes an executor and a handler as arguments. Finally, you need to return whatever your handler has collected. The following example shows how to do all of that: |
| 34 | + |
| 35 | +.A custom search method using `SearchExecutor` and `AttributesMapper` |
| 36 | +==== |
| 37 | +[source,java] |
| 38 | +[subs="verbatim,quotes"] |
| 39 | +---- |
| 40 | +package com.example.repo; |
| 41 | +
|
| 42 | +public class PersonRepoImpl implements PersonRepo { |
| 43 | + ... |
| 44 | + public List search(final Name base, final String filter, final String[] params, |
| 45 | + final SearchControls ctls) { |
| 46 | + **SearchExecutor executor = new SearchExecutor() { |
| 47 | + public NamingEnumeration executeSearch(DirContext ctx) { |
| 48 | + return ctx.search(base, filter, params, ctls); |
| 49 | + } |
| 50 | + };** |
| 51 | +
|
| 52 | + CollectingNameClassPairCallbackHandler handler = |
| 53 | + new AttributesMapperCallbackHandler(new PersonAttributesMapper()); |
| 54 | +
|
| 55 | + ldapTemplate.search(**executor**, handler); |
| 56 | + return handler.getList(); |
| 57 | + } |
| 58 | +} |
| 59 | +---- |
| 60 | +==== |
| 61 | + |
| 62 | +If you prefer the `ContextMapper` to the `AttributesMapper`, the following example shows what it would look like: |
| 63 | + |
| 64 | +.A custom search method using `SearchExecutor` and `ContextMapper` |
| 65 | +==== |
| 66 | +[source,java] |
| 67 | +[subs="verbatim,quotes"] |
| 68 | +---- |
| 69 | +package com.example.repo; |
| 70 | +
|
| 71 | +public class PersonRepoImpl implements PersonRepo { |
| 72 | + ... |
| 73 | + public List search(final Name base, final String filter, final String[] params, |
| 74 | + final SearchControls ctls) { |
| 75 | + SearchExecutor executor = new SearchExecutor() { |
| 76 | + public NamingEnumeration executeSearch(DirContext ctx) { |
| 77 | + return ctx.search(base, filter, params, ctls); |
| 78 | + } |
| 79 | + }; |
| 80 | +
|
| 81 | + CollectingNameClassPairCallbackHandler handler = |
| 82 | + **new ContextMapperCallbackHandler(new PersonContextMapper()**); |
| 83 | +
|
| 84 | + ldapTemplate.search(executor, handler); |
| 85 | + return handler.getList(); |
| 86 | + } |
| 87 | +} |
| 88 | +---- |
| 89 | +==== |
| 90 | + |
| 91 | +NOTE: When you use the `ContextMapperCallbackHandler`, you must make sure that you have called `setReturningObjFlag(true)` on your `SearchControls` instance. |
| 92 | + |
| 93 | +[[implementing-other-custom-context-methods]] |
| 94 | +== Implementing Other Custom Context Methods |
| 95 | + |
| 96 | +In the same manner as for custom `search` methods, you can actually call any method in `DirContext` by using a `ContextExecutor`, as follows: |
| 97 | + |
| 98 | +==== |
| 99 | +[source,java] |
| 100 | +[subs="verbatim,quotes"] |
| 101 | +---- |
| 102 | +public interface ContextExecutor { |
| 103 | + public Object executeWithContext(DirContext ctx) throws NamingException; |
| 104 | +} |
| 105 | +---- |
| 106 | +==== |
| 107 | + |
| 108 | +When implementing a custom `ContextExecutor`, you can choose between using the `executeReadOnly()` or the `executeReadWrite()` method. Suppose you want to call the following method: |
| 109 | + |
| 110 | +==== |
| 111 | +[source,java] |
| 112 | +[subs="verbatim,quotes"] |
| 113 | +---- |
| 114 | +Object lookupLink(Name name) |
| 115 | +---- |
| 116 | +==== |
| 117 | + |
| 118 | +The method is available in `DirContext`, but there is no matching method in `LdapTemplate`. It is a lookup method, so it should be read-only. We can implement it as follows: |
| 119 | + |
| 120 | +.A custom `DirContext` method using `ContextExecutor` |
| 121 | +==== |
| 122 | +[source,java] |
| 123 | +[subs="verbatim,quotes"] |
| 124 | +---- |
| 125 | +package com.example.repo; |
| 126 | +
|
| 127 | +public class PersonRepoImpl implements PersonRepo { |
| 128 | + ... |
| 129 | + public Object lookupLink(final Name name) { |
| 130 | + ContextExecutor executor = new ContextExecutor() { |
| 131 | + public Object executeWithContext(DirContext ctx) { |
| 132 | + return ctx.lookupLink(name); |
| 133 | + } |
| 134 | + }; |
| 135 | +
|
| 136 | + return ldapTemplate.executeReadOnly(executor); |
| 137 | + } |
| 138 | +} |
| 139 | +---- |
| 140 | +==== |
| 141 | + |
| 142 | +In the same manner, you can perform a read-write operation by using the `executeReadWrite()` method. |
| 143 | + |
| 144 | + |
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