EQL Internals - fieldenms/tg GitHub Wiki

Modifying / Extending EQL

Refer to the javadoc of package ua.com.fielden.platform.eql in platform-dao.

Transformation of EQL expressions

EQL expression (fluent API)
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        | Collect tokens
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        v
      Tokens
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        | Stage 0: Parsing
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        v
  AST level 1
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        | Stage 1
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        v
  AST level 2
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        | Stage 2
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        v
  AST level 3
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        | Stage 3
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        v
       SQL

Yielding in entity queries

An entity query with a single yield which is either unaliased or targets property id is equivalent to an entity query that selects all entities of that type whose id is contained[^1] in the yielded value.

[^1]: if the yielded value is a scalar, equality is used; in case of a set, membership test is used.

Discussion

• Parameterised entities
• Built-in conditioning
• Entity specific user-data-filtering
• Yielding of value type properties